M26 Hardware Design
GSM/GPRS Module Series
Rev. M26_Hardware_Design_V1.1
Date: 2014-11-24
www.quectel.com
GSM/GPRS Module Series
M26 Hardware Design
Our aim is to provide customers with timely and comprehensive service. For any
assistance, please contact our company headquarters:
Quectel Wireless Solutions Co., Ltd.
Office 501, Building 13, No.99, Tianzhou Road, Shanghai, China, 200233
Tel: +86 21 5108 6236
Mail: info@quectel.com
Or our local office, for more information, please visit:
http://www.quectel.com/support/salesupport.aspx
For technical support, to report documentation errors, please visit:
http://www.quectel.com/support/techsupport.aspx
GENERAL NOTES
QUECTEL OFFERS THIS INFORMATION AS A SERVICE TO ITS CUSTOMERS. THE INFORMATION
PROVIDED IS BASED UPON CUSTOMERS’ REQUIREMENTS. QUECTEL MAKES EVERY EFFORT
TO ENSURE THE QUALITY OF THE INFORMATION IT MAKES AVAILABLE. QUECTEL DOES NOT
MAKE ANY WARRANTY AS TO THE INFORMATION CONTAINED HEREIN, AND DOES NOT ACCEPT
ANY LIABILITY FOR ANY INJURY, LOSS OR DAMAGE OF ANY KIND INCURRED BY USE OF OR
RELIANCE UPON THE INFORMATION. ALL INFORMATION SUPPLIED HEREIN IS SUBJECT TO
CHANGE WITHOUT PRIOR NOTICE.
COPYRIGHT
THIS INFORMATION CONTAINED HERE IS PROPRIETARY TECHNICAL INFORMATION OF
QUECTEL CO., LTD. TRANSMITTABLE, REPRODUCTION, DISSEMINATION AND EDITING OF THIS
DOCUMENT AS WELL AS UTILIZATION OF THIS CONTENTS ARE FORBIDDEN WITHOUT
PERMISSION. OFFENDERS WILL BE HELD LIABLE FOR PAYMENT OF DAMAGES. ALL RIGHTS ARE
RESERVED IN THE EVENT OF A PATENT GRANT OR REGISTRATION OF A UTILITY MODEL OR
DESIGN.
Copyright © Quectel Wireless Solutions Co., Ltd. 2014. All rights reserved.
M26_Hardware_Design Confidential / Released 1 / 80
About the Document
Revision
Date
Author
Description
1.0
2014-08-07
Felix YIN
Initial
1.1
2014-11-24
Felix YIN
1. Modified output power of Bluetooth
2. Modified the timing of the RFTXMON signal
3. Updated Figure 5: Reference circuit for power
supply
4. Modified description of RTC and SIM card
interface
5. Modified description of UART Application
6. Deleted the over-voltage automatic shutdown
function
7. Modified the antenna gain in the Table 24
8. Modified the current consumption information in
Section 5.3 & 5.4
History
GSM/GPRS Module Series
M26 Hardware Design
M26_Hardware_Design Confidential / Released 2 / 80
GSM/GPRS Module Series
M26 Hardware Design
Contents
About the Document ................................................................................................................................... 2
Contents ....................................................................................................................................................... 3
Table Index ................................................................................................................................................... 6
Figure Index ................................................................................................................................................. 7
1 Introduction .......................................................................................................................................... 9
1.1. Safety Information.................................................................................................................... 10
2 Product Concept ................................................................................................................................ 11
2.1. General Description ................................................................................................................. 11
2.2. Key Features ........................................................................................................................... 12
2.3. Functional Diagram ................................................................................................................. 14
2.4. Evaluation Board ..................................................................................................................... 14
3 Application Interface ......................................................................................................................... 15
3.1. Pin of Module ........................................................................................................................... 16
3.1.1. Pin Assignment .............................................................................................................. 16
3.1.2. Pin Description ............................................................................................................... 17
3.2. Operating Modes ..................................................................................................................... 21
3.3. Power Supply ........................................................................................................................... 22
3.3.1. Power Features of Module ............................................................................................. 22
3.3.2. Decrease Supply Voltage Drop ...................................................................................... 23
3.3.3. Reference Design For Power Supply ............................................................................ 23
3.3.4. Monitor Power Supply .................................................................................................... 24
3.4. Power On and Down Scenarios .............................................................................................. 24
3.4.1. Power On ....................................................................................................................... 24
3.4.2. Power Down ................................................................................................................... 26
3.4.2.1. Power Down Module Using the PWRKEY Pin .................................................. 26
3.4.2.2. Power Down Module Using AT Command ........................................................ 27
3.4.2.3. Under-voltage Automatic Shutdown .................................................................. 28
3.4.3. Restart ............................................................................................................................ 28
3.5. Power Saving ........................................................................................................................... 29
3.5.1. Minimum Functionality Mode ......................................................................................... 29
3.5.2. SLEEP Mode .................................................................................................................. 29
3.5.3. Wake Up Module From SLEEP Mode ........................................................................... 30
3.5.4. Summary of State Transition .......................................................................................... 30
3.6. RTC Backup............................................................................................................................. 30
3.7. Serial Interfaces ....................................................................................................................... 32
3.7.1. UART Port ...................................................................................................................... 34
3.7.1.1. The Feature of UART Port................................................................................. 34
3.7.1.2. The Connection of UART .................................................................................. 35
M26_Hardware_Design Confidential / Released 3 / 80
GSM/GPRS Module Series
M26 Hardware Design
3.7.1.3. Firmware Upgrade ............................................................................................. 36
3.7.2. Debug Port ..................................................................................................................... 37
3.7.3. Auxiliary UART Port ....................................................................................................... 38
3.7.4. UART Application ........................................................................................................... 38
3.8. Audio Interfaces ....................................................................................................................... 40
3.8.1. Decrease TDD Noise and other Noise .......................................................................... 41
3.8.2. Microphone Interfaces Design ....................................................................................... 41
3.8.3. Receiver and Speaker Interface Design ........................................................................ 42
3.8.4. Earphone Interface Design ............................................................................................ 44
3.8.5. Audio Characteristics ..................................................................................................... 44
3.9. PCM Interface .......................................................................................................................... 45
3.9.1. Configuration .................................................................................................................. 45
3.9.2. Timing ............................................................................................................................. 46
3.9.3. Reference Design .......................................................................................................... 48
3.9.4. AT Command ................................................................................................................. 48
3.10. SIM Card Interface................................................................................................................... 49
3.11. ADC ......................................................................................................................................... 51
3.12. Behaviors of The RI ................................................................................................................. 51
3.13. Network Status Indication ........................................................................................................ 53
3.14. RF Transmitting Signal Indication ............................................................................................ 54
4 Antenna Interface ............................................................................................................................... 56
4.1. GSM Antenna Interface ........................................................................................................... 56
4.1.1. Reference Design .......................................................................................................... 56
4.1.2. RF Output Power ........................................................................................................... 57
4.1.3. RF Receiving Sensitivity ................................................................................................ 58
4.1.4. Operating Frequencies................................................................................................... 58
4.1.5. RF Cable Soldering ........................................................................................................ 59
4.2. Bluetooth Antenna Interface .................................................................................................... 59
5 Electrical, Reliability and Radio Characteristics ............................................................................ 61
5.1. Absolute Maximum Ratings ..................................................................................................... 61
5.2. Operating Temperature ............................................................................................................ 61
5.3. Power Supply Ratings ............................................................................................................. 62
5.4. Current Consumption .............................................................................................................. 63
5.5. Electro-static Discharge ........................................................................................................... 65
6 Mechanical Dimensions .................................................................................................................... 66
6.1. Mechanical Dimensions of Module .......................................................................................... 66
6.2. Recommended Footprint ......................................................................................................... 68
6.3. Top View of the Module ........................................................................................................... 69
6.4. Bottom View of the Module ...................................................................................................... 69
7 Storage and Manufacturing .............................................................................................................. 70
7.1. Storage..................................................................................................................................... 70
7.2. Soldering .................................................................................................................................. 71
M26_Hardware_Design Confidential / Released 4 / 80
GSM/GPRS Module Series
M26 Hardware Design
7.3. Packaging ................................................................................................................................ 71
7.3.1. Tape and Reel Packaging .............................................................................................. 72
8 Appendix A Reference ....................................................................................................................... 73
9 Appendix B GPRS Coding Scheme ................................................................................................. 78
10 Appendix C GPRS Multi-slot Class .................................................................................................. 80
11 FCC Warning ...................................................................................................................................... 81
M26_Hardware_Design Confidential / Released 5 / 80
GSM/GPRS Module Series
M26 Hardware Design
Table Index
TABLE 1: MODULE KEY FEATURES ............................................................................................................... 12
TABLE 2: CODING SCHEMES AND MAXIMUM NET DATA RATES OVER AIR INTERFACE ........................ 13
TABLE 3: IO PARAMETERS DEFINITION ........................................................................................................ 17
TABLE 4: PIN DESCRIPTION ........................................................................................................................... 17
TABLE 5: OVERVIEW OF OPERATING MODES ............................................................................................. 21
TABLE 6: SUMMARY OF STATE TRANSITION ............................................................................................... 30
TABLE 7: LOGIC LEVELS OF THE UART INTERFACE .................................................................................. 33
TABLE 8: PIN DEFINITION OF THE UART INTERFACES .............................................................................. 33
TABLE 9: PIN DEFINITION OF AUDIO INTERFACE ....................................................................................... 40
TABLE 10: TYPICAL ELECTRET MICROPHONE CHARACTERISTICS ......................................................... 44
TABLE 11: TYPICAL SPEAKER CHARACTERISTICS ..................................................................................... 44
TABLE 12: PIN DEFINITION OF PCM INTERFACE ......................................................................................... 45
TABLE 13: CONFIGURATION ........................................................................................................................... 45
TABLE 14: QPCMON COMMAND DESCRIPTION .......................................................................................... 48
TABLE 15: QPCMVOL COMMAND DESCRIPTION ......................................................................................... 49
TABLE 16: PIN DEFINITION OF THE SIM INTERFACE .................................................................................. 49
TABLE 17: PIN DEFINITION OF THE ADC ...................................................................................................... 51
TABLE 18: CHARACTERISTICS OF THE ADC ................................................................................................ 51
TABLE 19: BEHAVIORS OF THE RI ................................................................................................................. 51
TABLE 20: WORKING STATE OF THE NETLIGHT .......................................................................................... 53
TABLE 21: PIN DEFINITION OF THE RFTXMON ............................................................................................ 54
TABLE 22: PIN DEFINITION OF THE RF_ANT ................................................................................................ 56
TABLE 23: ANTENNA CABLE REQUIREMENTS ............................................................................................. 57
TABLE 24: ANTENNA REQUIREMENTS .......................................................................................................... 57
TABLE 25: THE MODULE CONDUCTED RF OUTPUT POWER .................................................................... 57
TABLE 26: THE MODULE CONDUCTED RF RECEIVING SENSITIVITY ....................................................... 58
TABLE 27: THE MODULE OPERATING FREQUENCIES ................................................................................ 58
TABLE 28: PIN DEFINITION OF THE BT_ANT ................................................................................................ 59
TABLE 29: ABSOLUTE MAXIMUM RATINGS .................................................................................................. 61
TABLE 30: OPERATING TEMPERATURE ........................................................................................................ 61
TABLE 31: THE MODULE POWER SUPPLY RATINGS .................................................................................. 62
TABLE 32: THE MODULE CURRENT CONSUMPTION .................................................................................. 63
TABLE 33: THE ESD ENDURANCE (TEMPERATURE: 25ºC, HUMIDITY: 45%) ............................................ 65
TABLE 34: RELATED DOCUMENTS ................................................................................................................ 73
TABLE 35: TERMS AND ABBREVIATIONS ...................................................................................................... 74
TABLE 36: DESCRIPTION OF DIFFERENT CODING SCHEMES .................................................................. 78
TABLE 37: GPRS MULTI-SLOT CLASSES ...................................................................................................... 80
M26_Hardware_Design Confidential / Released 6 / 80
GSM/GPRS Module Series
M26 Hardware Design
Figure Index
FIGURE 1: MODULE FUNCTIONAL DIAGRAM ............................................................................................... 14
FIGURE 2: PIN ASSIGNMENT ......................................................................................................................... 16
FIGURE 3: VOLTAGE RIPPLE DURING TRANSMITTING .............................................................................. 22
FIGURE 4: REFERENCE CIRCUIT FOR THE VBAT INPUT ........................................................................... 23
FIGURE 5: REFERENCE CIRCUIT FOR POWER SUPPLY ............................................................................ 24
FIGURE 6: TURN ON THE MODULE WITH AN OPEN-COLLECTOR DRIVER .............................................. 25
FIGURE 7: TURN ON THE MODULE WITH A BUTTON .................................................................................. 25
FIGURE 8: TURN-ON TIMING .......................................................................................................................... 26
FIGURE 9: TURN-OFF TIMING ........................................................................................................................ 27
FIGURE 10: TIMING OF RESTARTING SYSTEM ............................................................................................ 28
FIGURE 11: VRTC IS SUPPLIED BY A NON-CHARGEABLE BATTERY ........................................................ 31
FIGURE 12: VRTC IS SUPPLIED BY A RECHARGEABLE BATTERY ............................................................ 31
FIGURE 13: VRTC IS SUPPLIED BY A CAPACITOR ...................................................................................... 32
FIGURE 14: REFERENCE DESIGN FOR FULL-FUNCTION UART ................................................................ 35
FIGURE 15: REFERENCE DESIGN FOR UART PORT ................................................................................... 36
FIGURE 16: REFERENCE DESIGN FOR UART PORT WITH HARDWARE FLOW CONTROL .................... 36
FIGURE 17: REFERENCE DESIGN FOR FIRMWARE UPGRADE ................................................................. 37
FIGURE 18: REFERENCE DESIGN FOR DEBUG PORT ............................................................................... 37
FIGURE 19: REFERENCE DESIGN FOR AUXILIARY UART PORT ............................................................... 38
FIGURE 20: LEVEL MATCH DESIGN FOR 3.3V SYSTEM .............................................................................. 38
FIGURE 21: SKETCH MAP FOR RS-232 INTERFACE MATCH ...................................................................... 39
FIGURE 22: REFERENCE DESIGN FOR AIN ................................................................................................. 41
FIGURE 23: HANDSET INTERFACE DESIGN FOR AOUT1 ........................................................................... 42
FIGURE 24: SPEAKER INTERFACE DESIGN WITH AN AMPLIFIER FOR AOUT1 ....................................... 42
FIGURE 25: HANDSET INTERFACE DESIGN FOR AOUT2 ........................................................................... 43
FIGURE 26: SPEAKER INTERFACE DESIGN WITH AN AMPLIFIER FOR AOUT2 ....................................... 43
FIGURE 27: EARPHONE INTERFACE DESIGN .............................................................................................. 44
FIGURE 28: LONG SYNCHRONIZATION & SIGN EXTENSION DIAGRAM ................................................... 46
FIGURE 29: LONG SYNCHRONIZATION & ZERO PADDING DIAGRAM....................................................... 47
FIGURE 30: SHORT SYNCHRONIZATION & SIGN EXTENSION DIAGRAM ................................................. 47
FIGURE 31: SHORT SYNCHRONIZATION & ZERO PADDING DIAGRAM .................................................... 47
FIGURE 32: REFERENCE DESIGN FOR PCM ............................................................................................... 48
FIGURE 33: REFERENCE CIRCUIT FOR SIM INTERFACE WITH THE 6-PIN SIM CARD HOLDER ........... 50
FIGURE 34: RI BEHAVIOR OF VOICE CALLING AS A RECEIVER ................................................................ 52
FIGURE 35: RI BEHAVIOR AS A CALLER ....................................................................................................... 52
FIGURE 36: RI BEHAVIOR OF URC OR SMS RECEIVED ............................................................................. 52
FIGURE 37: REFERENCE DESIGN FOR NETLIGHT ..................................................................................... 53
FIGURE 38: RFTXMON SIGNAL DURING BURST TRANSMISSION ............................................................. 54
FIGURE 39: RFTXMON SIGNAL DURING CALL ............................................................................................. 55
FIGURE 40: REFERENCE DESIGN FOR GSM ANTENNA ............................................................................. 56
FIGURE 41: RF SOLDERING SAMPLE ........................................................................................................... 59
M26_Hardware_Design Confidential / Released 7 / 80
GSM/GPRS Module Series
M26 Hardware Design
FIGURE 42: REFERENCE DESIGN FOR BLUETOOTH ANTENNA ............................................................... 60
FIGURE 43: M26 MODULE TOP AND SIDE DIMENSIONS (UNIT: MM) ......................................................... 66
FIGURE 44: M26 MODULE BOTTOM DIMENSIONS (UNIT: MM) ................................................................... 67
FIGURE 45: RECOMMENDED FOOTPRINT (UNIT: MM) ................................................................................ 68
FIGURE 46: TOP VIEW OF THE MODULE ...................................................................................................... 69
FIGURE 47: BOTTOM VIEW OF THE MODULE .............................................................................................. 69
FIGURE 48: RAMP-SOAK-SPIKE REFLOW PROFILE .................................................................................... 71
FIGURE 49: TAPE AND REEL SPECIFICATION .............................................................................................. 72
FIGURE 50: DIMENSIONS OF REEL ............................................................................................................... 72
FIGURE 51: RADIO BLOCK STRUCTURE OF CS-1, CS-2 AND CS-3 ........................................................... 78
FIGURE 52: RADIO BLOCK STRUCTURE OF CS-4 ....................................................................................... 79
M26_Hardware_Design Confidential / Released 8 / 80
GSM/GPRS Module Series
M26 Hardware Design
1 Introduction
This document defines the M26 module and describes its hardware interface which are connected with
the customer application and the air interface.
This document can help you quickly understand module interface specifications, electrical and
mechanical details. Associated with application note and user guide, you can use M26 module to design
and set up mobile applications easily.
M26_Hardware_Design Confidential / Released 9 / 80
GSM/GPRS Module Series
Full attention must be given to driving at all times in order to reduce the risk of an
accident. Using a mobile while driving (even with a handsfree kit) cause distraction
and can lead to an accident. You must comply with laws and regulations restricting
the use of wireless devices while driving.
Switch off the cellular terminal or mobile before boarding an aircraft. Make sure it
switched off. The operation of wireless appliances in an aircraft is forbidden to
prevent interference with communication systems. Consult the airline staff about
the use of wireless devices on boarding the aircraft, if your device offers a Airplane
Mode which must be enabled prior to boarding an aircraft.
Switch off your wireless device when in hospitals or clinics or other health care
facilities. These requests are desinged to prevent possible interference with
sentitive medical equipment.
Cellular terminals or mobiles operate over radio frequency signal and cellular
network and cannot be guaranteed to connect in all conditions, for example no
mobile fee or an invalid SIM card. While you are in this condition and need
emergent help, please remember using emergency call. In order to make or
receive call, the cellular terminal or mobile must be switched on and in a service
area with adequate cellular signal strength.
Your cellular terminal or mobile contains a transmitter and receiver. When it is ON ,
it receives and transmits radio frequency energy. RF interference can occur if it is
used close to TV set, radio, computer or other electric equipment.
In locations with potencially explosive atmospheres, obey all posted signs to turn
off wireless devices such as your phone or other cellular terminals. Areas with
potencially exposive atmospheres including fuelling areas, below decks on boats,
fuel or chemical transfer or storage facilities, areas where the air contains
chemicals or particles such as grain, dust or metal powders.
M26 Hardware Design
1.1. Safety Information
The following safety precautions must be observed during all phases of the operation, such as usage,
service or repair of any cellular terminal or mobile incorporating M26 module. Manufacturers of the
cellular terminal should send the following safety information to users and operating personnel and to
incorporate these guidelines into all manuals supplied with the product. If not so, Quectel does not take on
any liability for customer failure to comply with these precautions.
M26_Hardware_Design Confidential / Released 10 / 80
GSM/GPRS Module Series
M26 Hardware Design
2 Product Concept
2.1. General Description
M26 is a Quad-band GSM/GPRS engine that works at frequencies of GSM850MHz, EGSM900MHz,
DCS1800MHz and PCS1900MHz. The M26 features GPRS multi-slot class 12 and supports the GPRS
coding schemes CS-1, CS-2, CS-3 and CS-4. For more details about GPRS multi-slot classes and coding
schemes, please refer to the Appendix B & C.
With a tiny profile of 15.8mm × 17.7mm × 2.3mm, the module can meet almost all the requirements for
M2M applications, including Vehicles and Personal Tracking, Security System, Wireless POS, Industrial
PDA, Smart Metering, and Remote Maintenance& Control, etc.
M26 is an SMD type module with LCC package, which can be easily embedded into applications. It
provides abundant hardware interfaces like PCM Interface.
Designed with power saving technique, the current consumption of M26 is as low as 1.3 mA in SLEEP
mode when DRX is 5.
M26 is integrated with Internet service protocols, such as TCP/UDP, FTP and PPP. Extended AT
commands have been developed for you to use these Internet service protocols easily.
M26 supports Bluetooth interface, it is fully compliant with Bluetooth specification 3.0.
The module fully complies with the RoHS directive of the European Union.
M26_Hardware_Design Confidential / Released 11 / 80
GSM/GPRS Module Series
Feature
Implementation
Power Supply
Single supply voltage: 3.3V ~ 4.6V
Typical supply voltage: 4V
Power Saving
Typical power consumption in SLEEP mode: 1.3 mA @DRX=5
1.2 mA @DRX=9
Frequency Bands
Quad-band: GSM850, EGSM900, DCS1800, PCS1900.
The module can search these frequency bands automatically
The frequency bands can be set by AT command
Compliant to GSM Phase 2/2+
GSM Class
Small MS
Transmitting Power
Class 4 (2W) at GSM850 and EGSM900
Class 1 (1W) at DCS1800 and PCS1900
GPRS Connectivity
GPRS multi-slot class 12 (default)
GPRS multi-slot class 1~12 (configurable)
GPRS mobile station class B
DATA GPRS
GPRS data downlink transfer: max. 85.6kbps
GPRS data uplink transfer: max. 85.6kbps
Coding scheme: CS-1, CS-2, CS-3 and CS-4
Support the protocols PAP (Password Authentication Protocol)
usually used for PPP connections
Internet service protocols TCP/UDP, FTP, PPP, HTTP, NTP, PING
Support Packet Broadcast Control Channel (PBCCH)
Support Unstructured Supplementary Service Data (USSD)
Temperature Range
Normal operation: -35°C ~ +80°C
Restricted operation: -40°C ~ -35°C and +80°C ~ +85°C 1)
Storage temperature: -45°C ~ +90°C
Bluetooth
Support Bluetooth specification 3.0
Output Power: Class 1 (Typical 7.5dBm)
SMS
Text and PDU mode
SMS storage: SIM card
SIM Interface
Support SIM card: 1.8V, 3.0V
Audio Features
Speech codec modes:
Half Rate (ETS 06.20)
Full Rate (ETS 06.10)
M26 Hardware Design
2.2. Key Features
The following table describes the detailed features of M26 module.
Table 1: Module Key Features
M26_Hardware_Design Confidential / Released 12 / 80
GSM/GPRS Module Series
1)
When the module works within this temperature range, the deviations from the GSM specification may
occur. For example, the frequency error or the phase error will be increased.
Enhanced Full Rate (ETS 06.50/06.60/06.80)
Adaptive Multi-Rate (AMR)
Echo Suppression
Noise Reduction
UART Interfaces
UART Port:
Seven lines on UART port interface
Used for AT command, GPRS data
Multiplexing function
Support autobauding from 4800bps to 115200bps
Debug Port:
Two lines on debug port interface DBG_TXD and DBG_RXD
Debug Port only used for firmware debugging
Auxiliary Port:
Used for AT command
Phonebook Management
Support phonebook types: SM, ME, ON, MC, RC, DC, LD, LA
SIM Application Toolkit
Support SAT class 3, GSM 11.14 Release 99
Real Time Clock
Supported
Physical Characteristics
Size: 15.8±0.15 × 17.7±0.15 × 2.3±0.2mm
Weight: Approx. 1.3g
Firmware Upgrade
Firmware upgrade via UART Port
Antenna Interface
Connected to antenna pad with 50 Ohm impedance control
Coding Scheme
1 Timeslot
2 Timeslot
4 Timeslot
CS-1
9.05kbps
18.1kbps
36.2kbps
CS-2
13.4kbps
26.8kbps
53.6kbps
CS-3
15.6kbps
31.2kbps
62.4kbps
CS-4
21.4kbps
42.8kbps
85.6kbps
NOTE
M26 Hardware Design
Table 2: Coding Schemes and Maximum Net Data Rates over Air Interface
M26_Hardware_Design Confidential / Released 13 / 80
GSM/GPRS Module Series
BB&RF
RF PAM
26MHzRF Transceiver
RTC
AUDIO
Serial
Interface
SIM
Interface
RF_ANT
VBAT
PWRKEY
VRTC
NETLIGHT
UART
SIM
Interface
ESD
PMU
MEMORY
BT_ANT
PWM
AUDIO
PCM
PCM
ADC
ADC
BT
VDD_EXT
VDD_EXT
M26 Hardware Design
2.3. Functional Diagram
The following figure shows a block diagram of M26 and illustrates the major functional parts.
Radio frequency part
Power management
The peripheral interface
—Power supply
—Turn-on/off interface
—UART interface
—Audio interface
—PCM interface
—SIM interface
—ADC interface
—RF interface
—BT interface
Figure 1: Module Functional Diagram
2.4. Evaluation Board
In order to help you to develop applications with M26, Quectel supplies an evaluation board (EVB),
RS-232 to USB cable, power adapter, earphone, antenna and other peripherals to control or test the
module. For details, please refer to the document [11].
M26_Hardware_Design Confidential / Released 14 / 80
GSM/GPRS Module Series
M26 Hardware Design
3 Application Interface
The module adopts LCC package and has 44 pins. The following chapters provide detailed descriptions
about these pins.
Pin of module
Operating modes
Power supply
Power on/down
Power saving
RTC
Serial interfaces
Audio interfaces
PCM interface
SIM card interface
ADC
Behaviors of the RI
Network status indication
RF transmitting signal indication
M26_Hardware_Design Confidential / Released 15 / 80
GSM/GPRS Module Series
AGND
SPK2P
MICP
MICN
SPK1P
SPK1N
PWRKEY
SIM_RST
SIM_CLK
CTS
VRTC
VBAT
GND
GND
DBG_TXD
DBG_RXD
GND
GND
RF_ANT
14
M26
Top View
15
16
17
18
19
20
21
22
36
37
38
39
40
41
42
43
44
1
2
3
4
5
6
7
8
9
10
11
12
13
23
24
25
26
27
28
29
30
31
32
33
34
35
AVDD
ADC0
SIM_GND
SIM_DATA
GND
PCM_OUT
PCM_IN
PCM_SYNC
PCM_CLK
TXD_AUX
RXD_AUX
GND
BT_ANT
RFTXMON
VDD_EXT
RTS
DCD
RI
DTR
TXD
RXD
NETLIGHT
RESERVED
SIM_VDD
VBAT
POWER
GND AUDIO
UART
SIM
PCM
ANT
OTHERS
RESERVED
Keep all reserved pins open.
NOTE
M26 Hardware Design
3.1. Pin of Module
3.1.1. Pin Assignment
Figure 2: Pin Assignment
M26_Hardware_Design Confidential / Released 16 / 80
GSM/GPRS Module Series
Type
Description
IO
Bidirectional input/output
DI
Digital input
DO
Digital output
PI
Power input
PO
Power output
AI
Analog input
AO
Analog output
Power Supply
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
VBAT
42,43
PI
Main power supply of
module:
VBAT=3.3V~4.6V
VImax=4.6V
VImin=3.3V
VInorm=4.0V
Make sure that
supply
sufficient
current in a
transmitting
burst typically
rises to 1.6A.
VRTC
44
IO
Power supply for RTC when
VBAT is not supplied for the
system.
Charging for backup battery or
golden capacitor when the
VBAT is applied.
VImax=3.3V
VImin=1.5V
VInorm=2.8V
VOmax=3V
VOmin=2V
VOnorm=2.8V
IOmax=2mA
Iin≈10uA
If unused, keep
this pin open.
VDD_
EXT
24
PO
Supply 2.8V voltage for
external circuit.
VOmax=2.9V
VOmin=2.7V
VOnorm=2.8V
IOmax=20mA
1. If unused,
keep this pin
open.
2. Recommend
to add a
M26 Hardware Design
3.1.2. Pin Description
Table 3: IO Parameters Definition
Table 4: Pin Description
M26_Hardware_Design Confidential / Released 17 / 80
GSM/GPRS Module Series
2.2~4.7uF
bypass
capacitor,
when using
this pin for
power supply.
GND
27,34
36,37
40,41
Ground
Turn on/off
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
PWRKEY
7
DI
Power on/off key. PWRKEY
should be pulled down for a
moment to turn on or turn off
the system.
VILmax=
0.1×VBAT
VIHmin=
0.6×VBAT
VIHmax=3.1V
Audio Interface
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
MICP
MICN
3,
4
AI
Positive and negative voice
input
Refer to Section 3.8
If unused, keep
these pins
open.
SPK1P
SPK1N
5,
6
AO
Channel 1 positive and
negative voice output
If unused, keep
these pins
open.
Support both
voice and
ringtone
output.
SPK2P
2
AO
Channel 2 voice output
AGND
1
Analog ground. Separate
ground connection for
external audio circuits.
If unused, keep
this pin open.
Network Status Indicator
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
NETLIGHT
16
DO
Network status indication
VOHmin=
0.85×VDD_EXT
VOLmax=
0.15×VDD_EXT
If unused,
keep this pin
open.
UART Port
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
M26 Hardware Design
M26_Hardware_Design Confidential / Released 18 / 80
GSM/GPRS Module Series
TXD
18
DO
Transmit data
VILmin=0V
VILmax=
0.25×VDD_EXT
VIHmin=
0.75×VDD_EXT
VIHmax=
VDD_EXT+0.2
VOHmin=
0.85×VDD_EXT
VOLmax=
0.15×VDD_EXT
If only use
TXD, RXD and
GND to
communicate,
recommended
to keep other
pins open.
RXD
17
DI
Receive data
DTR
19
DI
Data terminal ready
RI
20
DO
Ring indication
DCD
21
DO
Data carrier detection
CTS
22
DO
Clear to send
RTS
23
DI
Request to send
Debug Port
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
DBG_
TXD
39
DO
Transmit data
Same as above
If unused,
keep these
pins open.
DBG_
RXD
38
DI
Receive data
Auxiliary Port
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
TXD_
AUX
29
DO
Transmit data
Same as above
If unused,
keep these
pins open.
RXD_
AUX
28
DI
Receive data
SIM Interface
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
SIM_ VDD
14
PO
Power supply for SIM card
The voltage can be
selected by software
automatically. Either
1.8V or 3.0V.
All signals of
SIM interface
should be
protected
against ESD
with a TVS
diode array.
Maximum
trace length is
200mm from
the module
pad to SIM
card holder.
SIM_ CLK
13
DO
SIM clock
VOLmax=
0.15×SIM_VDD
VOHmin=
0.85×SIM_VDD
SIM_ DATA
11
IO
SIM data
VILmax=
0.25×SIM_VDD
VIHmin=
0.75×SIM_VDD
VOLmax=
0.15×SIM_VDD
VOHmin=
0.85×SIM_VDD
M26 Hardware Design
M26_Hardware_Design Confidential / Released 19 / 80
GSM/GPRS Module Series
SIM_ RST
12
DO
SIM reset
VOLmax=
0.15×SIM_VDD
VOHmin=
0.85×SIM_VDD
SIM_
GND
10 SIM ground
ADC
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
AVDD
8
PO
Reference voltage of
ADC circuit
VOmax=2.9V
VOmin=2.7V
VOnorm=2.8V
If unused,
keep this pin
open.
ADC0
9
AI
General purpose analog to
digital converter.
Voltage range:
0V to 2.8V
If unused,
keep this pin
open.
PCM
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
PCM_ CLK
30
DO
PCM clock
VILmin= 0V
VILmax=
0.25×VDD_EXT
VIHmin=
0.75×VDD_EXT
VIHmax=
VDD_EXT+0.2
VOHmin=
0.85×VDD_EXT
VOLmax=
0.15×VDD_EXT
If unused,
keep this pin
open.
PCM_
SYNC
31
DO
PCM frame
synchronization
PCM_
IN
32
DI
PCM data input
PCM_
OUT
33
DO
PCM data output
Antenna Interface
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
RF_
ANT
35
IO
GSM antenna pad
Impedance of 50Ω
BT_
ANT
26
IO
BT antenna pad
Impedance of 50Ω
If unused,
keep this pin
open.
Transmitting Signal Indication
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
RFTXMON
25
DO
Transmission signal
indication
VOHmin=
0.85×VDD_EXT
VOLmax=
If unused,
keep this pin
open.
M26 Hardware Design
M26_Hardware_Design Confidential / Released 20 / 80
GSM/GPRS Module Series
0.15×VDD_EXT
Other Interface
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
RESERVED
15
Keep these
pins open.
Mode
Function
Normal Operation
GSM/GPRS
Sleep
After enabling sleep mode by AT+QSCLK=1, the module will
automatically enter into Sleep Mode if DTR is set to high level
and there is no interrupt (such as GPIO interrupt or data on
UART port). In this case, the current consumption of module
will reduce to the minimal level.
During Sleep Mode, the module can still receive paging
message and SMS from the system normally.
GSM IDLE
Software is active. The module has registered to the GSM
network, and the module is ready to send and receive GSM
data.
GSM TALK
GSM connection is ongoing. In this mode, the power
consumption is decided by the configuration of Power Control
Level (PCL), dynamic DTX control and the working RF band.
GPRS IDLE
The module is not registered to GPRS network. The module is
not reachable through GPRS channel.
GPRS
STANDBY
The module is registered to GPRS network, but no GPRS PDP
context is active. The SGSN knows the Routing Area where the
module is located at.
GPRS READY
The PDP context is active, but no data transfer is ongoing. The
module is ready to receive or send GPRS data. The SGSN
knows the cell where the module is located at.
GPRS DATA
There is GPRS data in transfer. In this mode, power
consumption is decided by the PCL, working RF band and
GPRS multi-slot configuration.
M26 Hardware Design
3.2. Operating Modes
The table below briefly summarizes the various operating modes in the following chapters.
Table 5: Overview of Operating Modes
M26_Hardware_Design Confidential / Released 21 / 80
GSM/GPRS Module Series
Vdrop
4.615ms
577us
IBAT
VBAT
Burst:1.6A
POWER DOWN
Normal shutdown by sending the AT+QPOWD=1 command or using the
PWRKEY pin. The power management ASIC disconnects the power supply from
the base band part of the module, and only the power supply for the RTC is
remained. Software is not active. The UART interfaces are not accessible.
Operating voltage (connected to VBAT) remains applied.
Minimum
Functionality Mode
(without removing
power supply)
AT+CFUN command can set the module to a minimum functionality mode
without removing the power supply. In this case, the RF part of the module will not
work or the SIM card will not be accessible, or both RF part and SIM card will be
disabled, but the UART port is still accessible. The power consumption in this
case is very low.
M26 Hardware Design
3.3. Power Supply
3.3.1. Power Features of Module
The power supply is one of the key issues in designing GSM terminals. Because of the 577us radio burst
in GSM every 4.615ms, power supply must be able to deliver high current peaks in a burst period. During
these peaks, drops on the supply voltage must not exceed minimum working voltage of module.
For the M26 module, the max current consumption could reach to 1.6A during a burst transmission. It will
cause a large voltage drop on the VBAT. In order to ensure stable operation of the module, it is
recommended that the max voltage drop during the burst transmission does not exceed 400mV.
Figure 3: Voltage Ripple during Transmitting
M26_Hardware_Design Confidential / Released 22 / 80
GSM/GPRS Module Series
VBAT
C2C1
+
C3 C4
GND
100uF 100nF 10pF
0603
33pF
0603
M26 Hardware Design
3.3.2. Decrease Supply Voltage Drop
The power supply range of the module is 3.3V to 4.6V. Make sure that the input voltage will never drop
below 3.3V even in a burst transmission. If the power voltage drops below 3.3V, the module could turn off
automatically. For better power performance, it is recommended to place a 100uF tantalum capacitor with
low ESR (ESR=0.7Ω) and ceramic capacitor 100nF, 33pF and 10pF near the VBAT pin. The reference
circuit is illustrated in Figure 4.
The VBAT route should be wide enough to ensure that there is not too much voltage drop during burst
transmission. The width of trace should be no less than 2mm and the principle of the VBAT route is the
longer route, the wider trace.
3.3.3. Reference Design For Power Supply
The power design for the module is very important, since the performance of power supply for the module
largely depends on the power source. The power supply is capable of providing the sufficient current up to
2A at least. If the voltage drop between the input and output is not too high, it is suggested to use a LDO
as module’s power supply. If there is a big voltage difference between the input source and the desired
output (VBAT), a switcher power converter is recommended to use as a power supply.
The following figure shows a reference design for +5V input power source. The designed output for the
power supply is 4.0V and the maximum load current is 3A. In addition, in order to get a stable output
voltage, a zener diode is placed close to the pins of VBAT. As to the zener diode, it is suggested to use a
zener diode whose reverse zener voltage is 5.1V and dissipation power is more than 1 Watt.
Figure 4: Reference Circuit for the VBAT Input
M26_Hardware_Design Confidential / Released 23 / 80
GSM/GPRS Module Series
DC_IN
C1
C2
MIC29302WU U1
IN OUT
EN
GND
ADJ
2 4
1
3
5
VBAT
100nF
C3
470uFC4100nF
R2
D1
124K
56K
R3
470uF
5.1V
R4
470R
MCU_POWER_ON/OFF
47K
4.7K
R5
R6
R1
51K
It is suggested to control the module’s main power supply (VBAT) via LDO enable pin to restart the
module when the module has become abnormal. Power switch circuit like P-channel MOSFET switch
circuit can also be used to control VBAT.
NOTE
M26 Hardware Design
Figure 5: Reference Circuit for Power Supply
3.3.4. Monitor Power Supply
The command ―AT+CBC‖ can be used to monitor the supply voltage of the module. The unit of the
displayed voltage is mV.
For details, please refer to the document [1].
3.4. Power On and Down Scenarios
3.4.1. Power On
The module can be turned on by driving the pin PWRKEY to a low level voltage. An open collector driver
circuit is suggested to control the PWRKEY. A simple reference circuit is illustrated as below.
M26_Hardware_Design Confidential / Released 24 / 80
GSM/GPRS Module Series
Turn on pulse
PWRKEY
4.7K
47K
1. M26 module is set to autobauding mode (AT+IPR=0) by default. In the autobauding mode, URC ―RDY‖
is not reported to the host controller after module is powered on. When the module is powered on after
a delay of 4 or 5 seconds, it can receive AT command. Host controller should first send an AT string in
order that the module can detect baud rate of host controller, and it should continue to send the next AT
string until receiving OK string from the module. Then enter AT+IPR=x;&W to set a fixed baud rate for
the module and save the configuration to flash memory of the module. After these configurations, the
URC RDY would be received from the UART Port of the module every time when the module is
powered on. For more details, refer to the section AT+IPR in document [1].
2. When AT command is responded, indicates module is turned on successfully, or else the module fails
to be turned on.
PWRKEY
S1
Close to
S1
TVS
NOTE
M26 Hardware Design
Figure 6: Turn on the Module with an Open-collector Driver
The other way to control the PWRKEY is through a button directly. A TVS component is indispensable to
be placed nearby the button for ESD protection. For the best performance, the TVS component must be
placed nearby the button. When pressing the key, electrostatic strike may generate from finger. A
reference circuit is shown in the following figure.
Figure 7: Turn on the Module with a Button
M26_Hardware_Design Confidential / Released 25 / 80
GSM/GPRS Module Series
VDD_EXT
(OUTPUT)
VIL<0.1*VBAT
V
IH
> 0.6*VBAT
VBAT
PWRKEY
(INPUT)
54ms
>1s
T
1
OFF
BOOTING
MODULE
STATUS
RUNNING
Make sure that VBAT is stable before pulling down PWRKEY pin. The time of T1 is recommended to be
100ms.
NOTE
M26 Hardware Design
The turn-on timing is illustrated as the following figure.
Figure 8: Turn-on Timing
3.4.2. Power Down
The following procedures can be used to turn off the module:
Normal power down procedure: Turn off module using the PWRKEY pin
Normal power down procedure: Turn off module using command AT+QPOWD
Under-voltage automatic shutdown: Take effect when under-voltage is detected.
3.4.2.1. Power Down Module Using the PWRKEY Pin
It is a safe way to turn off the module by driving the PWRKEY to a low level voltage for a certain time. The
power down scenario is illustrated below.
M26_Hardware_Design Confidential / Released 26 / 80
GSM/GPRS Module Series
VBAT
PWRKEY
(INPUT)
VDD_EXT
(OUTPUT)
Logout net about 2s to 12s
0.7s<Pulldown<1s
1. This unsolicited result codes do not appear when autobauding is active and DTE and DCE are not
correctly synchronized after start-up. The module is recommended to set to a fixed baud rate.
2. As logout network time is related to the local mobile network, it is recommended to delay about 12
seconds before disconnecting the power supply or restarting the module.
NOTE
M26 Hardware Design
Figure 9: Turn-off Timing
The power down procedure causes the module to log off from the network and allows the firmware to
save important data before completely disconnecting the power supply.
Before the completion of the power down procedure, the module sends out the result code shown below:
NORMAL POWER DOWN
After that moment, no further AT commands can be executed. Then the module enters the power down
mode, the RTC is still active.
3.4.2.2. Power Down Module Using AT Command
It is also a safe way to turn off the module via AT command AT+QPOWD=1. This command will let the
module log off from the network and allow the firmware to save important data before completely
disconnecting the power supply.
Before the completion of the power down procedure the module sends out the result code shown below:
NORMAL POWER DOWN
After that moment, no further AT commands can be executed. And then the module enters the power
down mode, only the RTC is still active.
M26_Hardware_Design Confidential / Released 27 / 80
GSM/GPRS Module Series
These unsolicited result codes do not appear when autobauding is active and DTE and DCE are not
correctly synchronized after start-up. The module is recommended to set to a fixed baud rate.
PWRKEY
(INPUT)
VDD_EXT
(OUTPUT)
Turn off
Restart
Pull down the PWRKEY
to turn on the module
Delay >0.5s
NOTES
M26 Hardware Design
Please refer to the document [1] for details about the AT command AT+QPOWD.
3.4.2.3. Under-voltage Automatic Shutdown
The module will constantly monitor the voltage applied on the VBAT, if the voltage is ≤3.5V, the following
URC will be presented:
UNDER_VOLTAGE WARNING
The normal input voltage range is from 3.3V to 4.6V. If the voltage is <3.3V, the module would
automatically shut down itself.
If the voltage is <3.3V, the following URC will be presented:
UNDER_VOLTAGE POWER DOWN
After that moment, no further AT commands can be executed. The module logs off from network and
enters power down mode, and only RTC is still active.
3.4.3. Restart
You can restart the module by driving the PWRKEY to a low level voltage for a certain time, which is
similar to the way of turning on module. In order to make the internal LDOs discharge completely after
turning off the module, it is recommended to delay about 500ms before restarting the module. The restart
timing is illustrated as the following figure.
Figure 10: Timing of Restarting System
M26_Hardware_Design Confidential / Released 28 / 80
GSM/GPRS Module Series
M26 Hardware Design
3.5. Power Saving
Based on system requirements, there are several actions to drive the module to enter low current
consumption status. For example, AT+CFUN can be used to set module into minimum functionality mode
and DTR hardware interface signal can be used to lead system to SLEEP mode.
3.5.1. Minimum Functionality Mode
Minimum functionality mode reduces the functionality of the module to a minimum level. The consumption
of the current can be minimized when the slow clocking mode is activated at the same time. The mode is
set with the AT+CFUN command which provides the choice of the functionality levels <fun>=0, 1, 4.
0: minimum functionality
1: full functionality (default)
4: disable both transmitting and receiving of RF part
If the module is set to minimum functionality by AT+CFUN=0, the RF function and SIM card function
would be disabled. In this case, the UART port is still accessible, but all AT commands related with RF
function or SIM card function will be not available.
If the module has been set by the command with AT+CFUN=4, the RF function will be disabled, but the
UART port is still active. In this case, all AT commands related with RF function will be not available.
After the module is set by AT+CFUN=0 or AT+CFUN=4, it can return to full functionality by AT+CFUN=1.
For detailed information about AT+CFUN, please refer to the document [1].
3.5.2. SLEEP Mode
The SLEEP mode is disabled by default. You can enable it by AT+QSCLK=1. On the other hand, the
default setting is AT+QSCLK=0 and in this mode, the module cannot enter SLEEP mode.
When the module is set by the command with AT+QSCLK=1, you can control the module to enter or exit
from the SLEEP mode through pin DTR. When DTR is set to high level, and there is no on-air or hardware
interrupt such as GPIO interrupt or data on UART port, the module will enter SLEEP mode automatically.
In this mode, the module can still receive voice, SMS or GPRS paging from network, but the UART port
does not work.
M26_Hardware_Design Confidential / Released 29 / 80
GSM/GPRS Module Series
DTR pin should be held at low level during communication between the module and DTE.
Current Mode
Next Mode
Power Down
Normal Mode
Sleep Mode
Power Down
Use PWRKEY
Normal Mode
AT+QPOWD, use
PWRKEY pin
Use AT command
AT+QSCLK=1 and pull up
DTR
SLEEP Mode
Use PWRKEY pin
Pull DTR down or incoming
call or SMS or GPRS
NOTE
M26 Hardware Design
3.5.3. Wake Up Module From SLEEP Mode
When the module is in the SLEEP mode, the following methods can wake up the module.
If the DTR Pin is set low, it would wake up the module from the SLEEP mode. The UART port will be
active within 20ms after DTR is changed to low level.
Receive a voice or data call from network wakes up module.
Receive an SMS from network wakes up module.
3.5.4. Summary of State Transition
Table 6: Summary of State Transition
3.6. RTC Backup
The RTC (Real Time Clock) function is supported. The RTC is designed to work with an internal power
supply.
There are three kinds of designs for RTC backup power:
Use VBAT as the RTC power source.
When the module is turned off and the main power supply (VBAT) is remained, the real time clock is still
active as the RTC core is supplied by VBAT. In this case, the VRTC pin can be kept floating.
M26_Hardware_Design Confidential / Released 30 / 80
GSM/GPRS Module Series
Non-chargeable
Backup Battery
Module
RTC
Core
VBAT
Power Supply
LDO/DCDC
LDO
VRTC
1.5K
Rechargeable
Backup Battery
Module
RTC
Core
VBAT
Power Supply
LDO/DCDC
LDO
VRTC
1.5K
M26 Hardware Design
Use VRTC as the RTC power source.
If the main power supply (VBAT) is removed after the module is turned off, a backup supply such as a
coin-cell battery (rechargeable or non-chargeable) or a super-cap can be used to supply the VRTC pin to
keep the real time clock active.
Use VBAT and VRTC as the RTC power source.
As only powering the VRTC pin to keep the RTC will lead an error about 5 minutes a day, it is
recommended to power VBAT and VRTC pin at the same time when RTC function is needed. The
recommended supply for RTC core circuits are shown as below.
Figure 11: VRTC is Supplied by a Non-chargeable Battery
Figure 12: VRTC is Supplied by a Rechargeable Battery
M26_Hardware_Design Confidential / Released 31 / 80
GSM/GPRS Module Series
Module
RTC
Core
VBAT
Power Supply
LDO/DCDC
LDO
VRTC
1.5K
Large Capacitance
Capacitor
If you want to keep an accurate real time, please keep the main power supply VBAT alive.
NOTE
M26 Hardware Design
Figure 13: VRTC is Supplied by a Capacitor
A rechargeable or non-chargeable coin-cell battery can also be used here, for more information, please
visit http://www.sii.co.jp/en/.
3.7. Serial Interfaces
The module provides three serial ports: UART Port, Debug Port and Auxiliary UART Port. The module is
designed as a DCE (Data Communication Equipment), following the traditional DCE-DTE (Data Terminal
Equipment) connection. Autobauding function supports baud rate from 4800bps to 115200bps.
The UART Port:
TXD: Send data to RXD of DTE.
RXD: Receive data from TXD of DTE.
RTS: Request to send.
CTS: Clear to send.
DTR: DTE is ready and inform DCE (this pin can wake the module up).
RI: Ring indicator (when there is a call, SMS or URC output, the module will inform DTE with the RI
pin).
DCD: Data carrier detection (the validity of this pin demonstrates the communication link is set up).
M26_Hardware_Design Confidential / Released 32 / 80
GSM/GPRS Module Series
Hardware flow control is disabled by default. When hardware flow control is required, RTS and CTS
should be connected to the host. AT command AT+IFC=2,2 is used to enable hardware flow control. AT
command AT+IFC=0,0 is used to disable the hardware flow control. For more details, please refer to the
document [1].
Parameter
Min.
Max.
Unit
VIL 0 0.25×VDD_EXT
V
VIH
0.75×VDD_EXT
VDD_EXT +0.2
V
VOL 0 0.15×VDD_EXT
V
VOH
0.85×VDD_EXT
VDD_EXT
V
Interface
Pin Name
Pin No.
Description
UART Port
TXD
18
Transmit data
RXD
17
Receive data
DTR
19
Data terminal ready
RI
20
Ring indication
NOTE
M26 Hardware Design
The Debug Port:
DBG_TXD: Send data to the COM port of computer.
DBG_RXD: Receive data from the COM port of computer.
The Auxiliary UART Port:
TXD_AUX: Send data to the RXD of DTE.
RXD_AUX: Receive data from the TXD of DTE.
The logic levels are described in the following table.
Table 7: Logic Levels of the UART Interface
Table 8: Pin Definition of the UART Interfaces
M26_Hardware_Design Confidential / Released 33 / 80
GSM/GPRS Module Series
DCD
21
Data carrier detection
CTS
22
Clear to send
RTS
23
Request to send
Debug Port
DBG_RXD
38
Receive data
DBG_TXD
39
Transmit data
Auxiliary UART Port
RXD_AUX
28
Receive data
TXD_AUX
29
Transmit data
M26 Hardware Design
3.7.1. UART Port
3.7.1.1. The Feature of UART Port
Seven lines on UART interface
Contain data lines TXD and RXD, hardware flow control lines RTS and CTS, other control lines DTR,
DCD and RI.
Used for AT command, GPRS data, etc. Multiplexing function is supported on the UART Port. So far
only the basic mode of multiplexing is available.
Support the communication baud rates as the following:
300, 600, 1200, 2400, 4800, 9600, 14400, 19200, 28800, 38400, 57600, 115200.
The default setting is autobauding mode. Support the following baud rates for Autobauding function:
4800, 9600, 19200, 38400, 57600, 115200.
The module disables hardware flow control by default. AT command AT+IFC=2,2 is used to enable
hardware flow control.
After setting a fixed baud rate or autobauding, please send ―AT‖ string at that rate. The UART port is
ready when it responds ―OK‖.
Autobauding allows the module to detect the baud rate by receiving the string ―AT‖ or ―at‖ from the host or
PC automatically, which gives module flexibility without considering which baud rate is used by the host
controller. Autobauding is enabled by default. To take advantage of the autobauding mode, special
attention should be paid according to the following requirements:
Synchronization between DTE and DCE:
When DCE (the module) powers on with the autobauding enabled, it is recommended to wait 2 to 3
seconds before sending the first AT character. After receiving the ―OK‖ response, DTE and DCE are
correctly synchronized.
M26_Hardware_Design Confidential / Released 34 / 80
GSM/GPRS Module Series
To assure reliable communication and avoid any problems caused by undetermined baud rate between
DCE and DTE, it is strongly recommended to configure a fixed baud rate and save it instead of using
autobauding after start-up. For more details, please refer to the Section AT+IPR in document [1].
TXD
RXD
RTS
CTS
DTR
DCD
RI
TXD
RXD
RTS
CTS
DTR
DCD
RING
Module (DCE)
Serial portUART port
GND GND
PC (DTE)
NOTE
M26 Hardware Design
If the host controller needs URC in the mode of autobauding, it must be synchronized firstly. Otherwise
the URC will be discarded.
Restrictions on autobauding operation:
The UART port has to be operated at 8 data bits, no parity and 1 stop bit (factory setting).
The ―At‖ and ―aT‖ commands cannot be used.
Only the strings ―AT‖ or ―at‖ can be detected (neither ―At‖ nor ―aT‖).
The Unsolicited Result Codes like RDY, +CFUN: 1 and +CPIN: READY will not be indicated when
the module is turned on with autobauding enabled and not be synchronized.
Any other Unsolicited Result Codes will be sent at the previous baud rate before the module detects
the new baud rate by receiving the first ―AT‖ or ―at‖ string. The DTE may receive unknown characters
after switching to new baud rate.
It is not recommended to switch to autobauding from a fixed baud rate.
If autobauding is active it is not recommended to switch to multiplex mode.
3.7.1.2. The Connection of UART
The connection between module and host using UART Port is very flexible. Three connection styles are
illustrated as below.
Reference design for Full-Function UART connection is shown as below when it is applied in
modulation-demodulation.
M26_Hardware_Design Confidential / Released 35 / 80
Figure 14: Reference Design for Full-Function UART
GSM/GPRS Module Series
TXD
RXD
GND
UART port
TXD
RXD
GND
Module (DCE)
Host (DTE)
Controller
RTS
CTS
RTS
CTS
GND
RXD
TXD TXD
RXD
GND
Module (DCE)
Host (DTE)
Controller
M26 Hardware Design
Three-line connection is shown as below.
Figure 15: Reference Design for UART Port
UART Port with hardware flow control is shown as below. This connection will enhance the reliability of
the mass data communication.
Figure 16: Reference Design for UART Port with Hardware Flow Control
3.7.1.3. Firmware Upgrade
The TXD, RXD can be used to upgrade firmware. The PWRKEY pin must be pulled down before firmware
upgrade. The reference circuit is shown as below:
M26_Hardware_Design Confidential / Released 36 / 80
GSM/GPRS Module Series
IO Connector
TXD
RXD
GND
PWRKEY
Module (DCE)
UART port
TXD
RXD
GND
PWRKEY
The firmware of module might need to be upgraded due to certain reasons. It is recommended to reserve
these pins in the host board for firmware upgrade.
Peripheral
TXD
RXD
GND
Module
DBG_TXD
DBG_RXD
GND
NOTE
M26 Hardware Design
Figure 17: Reference Design for Firmware Upgrade
3.7.2. Debug Port
Two lines: DBG_TXD and DBG_RXD.
It outputs log information automatically.
Debug Port is only used for firmware debugging and its baud rate must be configured as 460800bps.
Figure 18: Reference Design for Debug Port
M26_Hardware_Design Confidential / Released 37 / 80
GSM/GPRS Module Series
Peripheral
TXD
RXD
GND
Module
TXD_AUX
RXD_AUX
GND
Peripheral
/TXD
/RXD
1K
TXD
RXD
RTS
CTS
DTR
RI
/RTS
/CTS
GPIO
EINT
GPIO DCD
Module
1K
1K
Voltage level:3.3V
5.6K
5.6K
5.6K
1K
1K
1K
1K
GND GND
M26 Hardware Design
3.7.3. Auxiliary UART Port
Two data lines: TXD_AUX and RXD_AUX.
Auxiliary UART port is used for AT command only and does not support GPRS data, Multiplexing
function etc.
Auxiliary UART port supports the communication baud rates as the following:
1200, 2400, 4800, 9600, 14400, 19200, 28800, 38400, 57600, 115200.
Auxiliary UART port could be used when you send AT+QEAUART=1 string on the UART port.
The default baud rate setting is 115200bps, and does not support autobauding. The baud rate can be
modified by AT+QSEDCB command. For more details, please refer to the document [1].
3.7.4. UART Application
The reference design of 3.3V level match is shown as below. If the host is a 3V system, please change
the 5.6K resistor to 10K.
M26_Hardware_Design Confidential / Released 38 / 80
Figure 19: Reference Design for Auxiliary UART Port
Figure 20: Level Match Design for 3.3V System
GSM/GPRS Module Series
It is highly recommended to add the resistor divider circuit on the UART signal lines when the host’s level
is 3V or 3.3V. For the higher voltage level system, a level shifter IC could be used between the host and
the module. For more details about UART circuit design, please refer to document [13].
TXD
RXD
RTS
CTS
DTR
RI
DCD
Module
GND
C1+
C1-
C2+
C2-
V+
VCC
GND
V-
3.3V
T1IN
T2IN
T3IN
T4IN
R1IN
R2IN
R3IN
R1OUT
R2OUT
R3OUT
T1OUT
T2OUT
T5OUT
T3OUT
T4OUT
T5IN
GND
GND
/R1OUT
1
2
3
4
5
6
7
8
9
GND
To PC Serial Port
GND
1K
1K
1K
1K
1K
5.6K5.6K
1K
1K
5.6K
RS-232 Level Shifter
NOTE
M26 Hardware Design
The following figure shows a sketch map between module and standard RS-232 interface. Since the
electrical level of module is 2.8V, so a RS-232 level shifter must be used. Note that you should assure the
IO voltage of level shifter which connects to module is 2.8V.
Figure 21: Sketch Map for RS-232 Interface Match
Please visit vendor web site to select suitable IC, such as: http://www.maximintegrated.com and
http://www.exar.com/.
M26_Hardware_Design Confidential / Released 39 / 80
GSM/GPRS Module Series
Interface
Pin Name
Pin No.
Description
AIN/AOUT1
MICP
3
Microphone positive input
MICN
4
Microphone negative input
SPK1P
5
Channel 1 Audio positive output
SPK1N
6
Channel 1 Audio negative output
AIN/AOUT2
MICP
3
Microphone positive input
MICN
4
Microphone negative input
SPK2P
2
Channel 2 Audio positive output
AGND
1
Form a pseudo-differential pair with SPK2P
M26 Hardware Design
3.8. Audio Interfaces
The module provides one analog input channels and two analog output channels.
Table 9: Pin Definition of Audio Interface
AIN can be used for input of microphone and line. An electret microphone is usually used. AIN are
differential input channels.
AOUT1 is used for output of the receiver. This channel is typically used for a receiver built into a handset.
AOUT1 channel is a differential channel.
AOUT2 is typically used with earphone. It is a single-ended and mono channel. SPK2P and AGND can
establish a pseudo differential mode.
All of these two audio channels support voice and ringtone output, and so on, and can be switched by
AT+QAUDCH command. For more details, please refer to the document [1].
Use AT command AT+QAUDCH to select audio channel:
0--AIN/AOUT1, the default value is 0.
1--AIN/AOUT2, this channel is always used for earphone.
For each channel, you can use AT+QMIC to adjust the input gain level of microphone. You can also use
AT+CLVL to adjust the output gain level of receiver and speaker. AT+QSIDET is used to set the
side-tone gain level. For more details, please refer to the document [1].
M26_Hardware_Design Confidential / Released 40 / 80
GSM/GPRS Module Series
MICP
Differential
layout
Module
10pF
33pF
33pF
33pF
GND
GND
Electret
Microphone
GND
GND
10pF
10pF
GND
GND
ESD
ESD
Close to Module
MICN
GND
GND
Close to Microphone
0603
0603
0603
0603
0603
0603
33pF
0603
33pF
0603
33pF
0603
10pF
0603
10pF
0603
10pF
0603
M26 Hardware Design
3.8.1. Decrease TDD Noise and other Noise
The 33pF capacitor is applied for filtering out 900MHz RF interference when the module is transmitting at
EGSM900MHz. Without placing this capacitor, TDD noise could be heard. Moreover, the 10pF capacitor
here is for filtering out 1800MHz RF interference. However, the resonant frequency point of a capacitor
largely depends on the material and production technique. Therefore, customer would have to discuss
with its capacitor vendor to choose the most suitable capacitor for filtering out GSM850MHz,
EGSM900MHz, DCS1800MHz and PCS1900MHz separately.
The severity degree of the RF interference in the voice channel during GSM transmitting period largely
depends on the application design. In some cases, EGSM900 TDD noise is more severe; while in other
cases, DCS1800 TDD noise is more obvious. Therefore, you can have a choice based on test results.
Sometimes, even no RF filtering capacitor is required.
The capacitor which is used for filtering out RF noise should be close to audio interface or other audio
interfaces. Audio alignment should be as short as possible.
In order to decrease radio or other signal interference, the position of RF antenna should be kept away
from audio interface and audio alignment. Power alignment and audio alignment should not be parallel,
and power alignment should be far away from audio alignment.
The differential audio traces have to be placed according to the differential signal layout rule.
3.8.2. Microphone Interfaces Design
AIN channel come with internal bias supply for external electret microphone. A reference circuit is shown
in the following figure.
M26_Hardware_Design Confidential / Released 41 / 80
Figure 22: Reference Design for AIN
GSM/GPRS Module Series
SPK1P
SPK1N
Differential layout
Module
10pF
0603
Close to speaker
GND
ESD
33pF
0603
33pF
0603
GND
10pF
0603
ESD
10pF
0603
33pF
0603
SPK1P
SPK1N
Differential
layout
Amplifier
circuit
Module
10pF
0603
Close to speaker
GND
ESD
33pF
0603
33pF
0603
GND
10pF
0603
ESD
10pF
0603
33pF
0603
M26 Hardware Design
3.8.3. Receiver and Speaker Interface Design
Figure 23: Handset Interface Design for AOUT1
Figure 24: Speaker Interface Design with an Amplifier for AOUT1
M26_Hardware_Design Confidential / Released 42 / 80
GSM/GPRS Module Series
SPK2P
AGND
Differential layout
10pF
0603
33pF
0603
Close to Speaker
GND
ESD
Module
22uF
Module
SPK2P
AGND
Differential layout
Amplifier
circuit
10pF
0603
10pF
0603
33pF
0603
33pF
0603
Close to Speaker
GND
GND
ESD
ESD
C2
C1
The value of C1 and C2 here depends on the input impedance of audio amplifier.
NOTE
M26 Hardware Design
Figure 25: Handset Interface Design for AOUT2
Figure 26: Speaker Interface Design with an Amplifier for AOUT2
The suitable differential audio amplifier can be chosen from the Texas Instrument’s website
(http://www.ti.com/). There are also other excellent audio amplifier vendors in the market.
1.
M26_Hardware_Design Confidential / Released 43 / 80
GSM/GPRS Module Series
1
2
4
3
MICP
22uF
33pF
GND
AGND
Close to Socket
AGND
33pF
10pF
GND
AGND
Module
4.7uF
SPK2P
Close to Module
GND
33pF
33pF
Differential
layout
33pF
MICN
0603
0603
0603 0603
06030603
0603
10pF
GND
10pF
0603
0603
0603
10pF
10pF
Parameter
Min.
Typ.
Max.
Unit
Working Voltage
1.2
1.5
2.0
V
Working Current
200
500
uA
External Microphone Load Resistance
2.2 K Ohm
Parameter
Min.
Typ.
Max.
Unit
AOUT1
Output
Single-ended
Load resistance
32 Ohm
Ref level
0 2.4
Vpp
Differential
Load resistance
32 Ohm
Ref level
0 4.8
Vpp
M26 Hardware Design
3.8.4. Earphone Interface Design
Figure 27: Earphone Interface Design
3.8.5. Audio Characteristics
Table 10: Typical Electret Microphone Characteristics
Table 11: Typical Speaker Characteristics
M26_Hardware_Design Confidential / Released 44 / 80
GSM/GPRS Module Series
AOUT2
Output
Single-ended
Load resistance
32
Load
Resistance
Reference level
0 2.4
Vpp
Pin Name
Pin No.
Description
PCM_CLK
30
PCM clock output
PCM_SYNC
31
PCM frame synchronization output
PCM_IN
32
PCM data input
PCM_OUT
33
PCM data output
PCM
Line Interface Format
Linear
Data Length
Linear: 13 bits
M26 Hardware Design
3.9. PCM Interface
M26 supports PCM interface. It is used for digital audio transmission between the module and the device.
This interface is composed of PCM_CLK, PCM_SYNC, PCM_IN and PCM_OUT signal lines.
Pulse-code modulation (PCM) is a converter that changes the consecutive analog audio signal to discrete
digital signal. The whole procedure of Pulse-code modulation contains sampling, quantizing and
encoding.
Table 12: Pin Definition of PCM Interface
3.9.1. Configuration
M26 module supports 13-bit line code PCM format. The sample rate is 8 KHz, and the clock source is 256
KHz, and the module can only act as master mode. The PCM interface supports both long and short
synchronization simultaneously. Furthermore, it only supports MSB first. For detailed information, please
refer to the table below.
Table 13: Configuration
M26_Hardware_Design Confidential / Released 45 / 80
GSM/GPRS Module Series
12 11 10
9 8 7 6 5 4 3 2 1 0
12 11 10 9 8 7 6 5 4 3 2 1 0
PCM_CLK
PCM_SYNC
PCM_OUT
PCM_IN
MSB
MSB
Sign
extension
Sign
extension
Sample Rate
8KHz
PCM Clock/Synchronization Source
PCM master mode: clock and synchronization is
generated by module
PCM Synchronization Rate
8KHz
PCM Clock Rate
PCM master mode: 256 KHz (line)
PCM Synchronization Format
Long/short synchronization
PCM Data Ordering
MSB first
Zero Padding
Yes
Sign Extension
Yes
M26 Hardware Design
3.9.2. Timing
The sample rate of the PCM interface is 8 KHz and the clock source is 256 KHz, so every frame contains
32 bits data, since M26 supports 16 bits line code PCM format, the left 16 bits are invalid. The following
diagram shows the timing of different combinations. The synchronization length in long synchronization
format can be programmed by firmware from one bit to eight bits. In the Sign extension mode, the high
three bits of 16 bits are sign extension, and in the Zero padding mode, the low three bits of 16 bits are
zero padding.
Under zero padding mode, you can configure the PCM input and output volume by executing
AT+QPCMVOL command. For more details, please refer to Chapter 3.9.4.
Figure 28: Long Synchronization & Sign Extension Diagram
M26_Hardware_Design Confidential / Released 46 / 80
GSM/GPRS Module Series
12 11 10 9 8 7 6 5 4 3 2 1 0
12 11 10 9 8 7 6 5 4 3 2 1 0
PCM_CLK
PCM_SYNC
PCM_OUT
PCM_IN
MSB
MSB
Zero padding
Zero padding
PCM_CLK
PCM_SYNC
PCM_OUT
PCM_IN
12 11 10 9 8 7 6 5 4 3 2 1 0
12 11 10 9 8 7 6 5 4 3 2 1 0
MSB
MSB
Sign extension
Sign extension
PCM_CLK
PCM_SYNC
PCM_OUT
PCM_IN
12 11 10 9 8 7 6 5 4 3 2 1 0
12 11 10 9 8 7 6 5 4 3 2 1 0
MSB
MSB
Zero padding
Zero padding
M26 Hardware Design
Figure 29: Long Synchronization & Zero Padding Diagram
Figure 30: Short Synchronization & Sign Extension Diagram
Figure 31: Short Synchronization & Zero Padding Diagram
M26_Hardware_Design Confidential / Released 47 / 80
GSM/GPRS Module Series
PCM_SYNC
PCM_CLK
PCM_OUT
PCM_IN
PCM_SYNC
PCM_CLK
PCM_IN
PCM_OUT
Module
(Master)
Peripheral
(Slave)
Parameter
Scope
Description
Mode
0~2
0: Close PCM
1: Open PCM
2: Open PCM when audio talk is set up
Sync_Type
0~1
0: Short synchronization
1: Long synchronization
Sync_Length
1~8
Programmed from one bit to eight bit
SignExtension
0~1
0: Zero padding
1: Sign extension
MSBFirst
0~1
0: MSB first
1: Not support
M26 Hardware Design
3.9.3. Reference Design
M26 can only work as a master, providing synchronization and clock source. The reference design is
shown as below.
Figure 32: Reference Design for PCM
3.9.4. AT Command
There are two AT commands about the configuration of PCM, listed as below.
AT+QPCMON can configure operating mode of PCM.
AT+QPCMON=mode, Sync_Type, Sync_Length, SignExtension, MSBFirst
Table 14: QPCMON Command Description
M26_Hardware_Design Confidential / Released 48 / 80
GSM/GPRS Module Series
Parameter
Scope
Description
vol_pcm_in
0~32767
Set the input volume
vol_pcm_out
0~32767
Set the output volume
The voice may be distorted when this value exceeds 16384.
Pin Name
Pin No.
Description
SIM_VDD
14
Supply power for SIM card. Automatic detection of SIM card voltage.
3.0V±5% and 1.8V±5%. Maximum supply current is around 10mA.
SIM_CLK
13
SIM card clock.
SIM_DATA
11
SIM card data I/O.
SIM_RST
12
SIM card reset.
SIM_GND
10
SIM card ground.
M26 Hardware Design
AT+QPCMVOL can configure the volume of input and output.
AT+QPCMVOL=vol_pcm_in, vol_pcm_out
Table 15: QPCMVOL Command Description
3.10. SIM Card Interface
The SIM interface supports the functionality of the GSM Phase 1 specification and also supports the
functionality of the new GSM Phase 2+ specification for FAST 64 kbps SIM card, which is intended for
use with a SIM application Tool-kit.
The SIM interface is powered by an internal regulator in the module. Both 1.8V and 3.0V SIM Cards are
supported.
Table 16: Pin Definition of the SIM Interface
M26_Hardware_Design Confidential / Released 49 / 80
GSM/GPRS Module Series
Module
SIM_VDD
SIM_GND
SIM_RST
SIM_CLK
SIM_DATA
22R
22R
22R
100nF
SIM_Holder
GND
TVS
33pF33pF 33pF
VCC
RST
CLK IO
VPP
GND
GND
33pF
M26 Hardware Design
The reference circuit for a 6-pin SIM card socket is illustrated as the following figure.
Figure 33: Reference Circuit for SIM Interface with the 6-pin SIM Card Holder
For more information of SIM card holder, you can visit http://www.amphenol.com and
http://www.molex.com .
In order to enhance the reliability and availability of the SIM card in application. Please follow the below
criteria in the SIM circuit design:
Keep layout of SIM card as close as possible to the module. Assure the possibility of the length of the
trace is less than 200mm.
Keep SIM card signal away from RF and VBAT alignment.
Assure the ground between module and SIM cassette short and wide. Keep the width of ground no
less than 0.5mm to maintain the same electric potential. The decouple capacitor of SIM_VDD is less
than 1uF and must be near to SIM cassette.
To avoid cross talk between SIM_DATA and SIM_CLK. Keep them away with each other and shield
them with surrounded ground.
In order to offer good ESD protection, it is recommended to add a TVS diode array. For more
information of TVS diode, please visit http://www.onsemi.com/. The most important rule is to place
the ESD protection device close to the SIM card socket and make sure the nets being protected will
go through the ESD device first and then lead to module. The 22Ω resistors should be connected in
series between the module and the SIM card so as to suppress the EMI spurious transmission and
enhance the ESD protection. Please to be noted that the SIM peripheral circuit should be close to the
SIM card socket.
Place the RF bypass capacitors (33pF) close to the SIM card on all signals line for improving EMI.
M26_Hardware_Design Confidential / Released 50 / 80
GSM/GPRS Module Series
Pin Name
Pin No.
Description
AVDD
8
Reference voltage of ADC circuit
ADC0
9
Analog to digital converter.
Item
Min.
Typ.
Max.
Units
Voltage Range
0 2.8
V
ADC Resolution
10 bits
ADC Accuracy
2.7 mV
State
RI Response
Standby
HIGH
Voicecall
Change to LOW, then:
1. Change to HIGH when call is established.
2. Use ATH to hang up the call, RI changes to HIGH.
3. Calling part hangs up, RI changes to HIGH first, and changes to LOW for
120ms indicating ―NO CARRIER‖ as an URC, then changes to HIGH again.
4. Change to HIGH when SMS is received.
SMS
When a new SMS comes, the RI changes to LOW and holds low level for about
M26 Hardware Design
3.11. ADC
The module provides an ADC channel to measure the value of voltage. Please give priority to the use of
ADC0 channel. The command AT+QADC can read the voltage value applied on ADC0 pin. For details of
this AT command, please refer to the document [1]. In order to improve the accuracy of ADC, the layout
of ADC should be surrounded by ground.
Table 17: Pin Definition of the ADC
Table 18: Characteristics of the ADC
3.12. Behaviors of The RI
Table 19: Behaviors of the RI
M26_Hardware_Design Confidential / Released 51 / 80
GSM/GPRS Module Series
RI
Idle Ring
Off-hook by “ATA”
On-hook by “ATH”
HIGH
LOW
SMS received
RI
Idle Calling
On-hook
Talking
HIGH
LOW
Idle
RI
Idle or
Talking
URC or
SMS received
HIGH
LOW
120ms
120ms, then changes to HIGH.
URC
Certain URCs can trigger 120ms low level on RI. For more details, please refer to
the document [1]
M26 Hardware Design
If the module is used as a caller, the RI would maintain high except the URC or SMS is received. On the
other hand, when it is used as a receiver, the timing of the RI is shown below.
Figure 34: RI Behavior of Voice Calling as a Receiver
Figure 35: RI Behavior as a Caller
M26_Hardware_Design Confidential / Released 52 / 80
Figure 36: RI Behavior of URC or SMS Received
GSM/GPRS Module Series
Module
NETLIGHT
4.7K
47K
300R
VBAT
State
Module Function
Off
The module is not running.
64ms On/800ms Off
The module is not synchronized with network.
64ms On/2000ms Off
The module is synchronized with network.
64ms On/600ms Off
The GPRS data transmission after dialing the PPP connection.
M26 Hardware Design
3.13. Network Status Indication
The NETLIGHT signal can be used to drive a network status indicator LED. The working state of this pin
is listed in the following table.
Table 20: Working State of the NETLIGHT
A reference circuit is shown as below.
Figure 37: Reference Design for NETLIGHT
M26_Hardware_Design Confidential / Released 53 / 80
GSM/GPRS Module Series
Transmit burst
RFTXMON
577us220us
220us 577us
4.615ms
Pin Name
Pin No.
Description
RFTXMON
25
Transmission signal indication
M26 Hardware Design
3.14. RF Transmitting Signal Indication
The M26 provides a RFTXMON pins which will rise when the transmitter is active and fall after the
transmitter activity is completed.
Table 21: Pin Definition of the RFTXMON
There are two different modes for this function:
1) Active during the TX activity
RFTXMON pin is used to indicate the TX burst, when it outputs a high level, 220us later there will be a TX
burst.
You can execute AT+QCFG=“RFTXburst”, 1 to enable the function.
The timing of the RFTXMON signal is shown below.
M26_Hardware_Design Confidential / Released 54 / 80
Figure 38: RFTXMON Signal during Burst Transmission
GSM/GPRS Module Series
RFTXMON
Idle
Calling Hanged up
HIGH
LOW
M26 Hardware Design
2) Active during the Call
RFTXMON will be HIGH during a call and the pin will become LOW after being hanged up.
You can execute AT+QCFG=“RFTXburst”, 2 to enable the function.
The timing of the RFTXMON signal is shown below.
Figure 39: RFTXMON Signal during Call
M26_Hardware_Design Confidential / Released 55 / 80
GSM/GPRS Module Series
Module
RF_ANT
0R
NM NM
Pin Name
Pin No.
Description
GND
34
Ground
RF_ANT
35
GSM antenna pad
GND
36
Ground
GND
37
Ground
M26 Hardware Design
4 Antenna Interface
M26 has two antenna interfaces, GSM antenna and BT antenna. The Pin 26 is the Bluetooth antenna pad.
The Pin 35 is the GSM antenna pad. The RF interface of the two antenna pad has an impedance of 50Ω.
4.1. GSM Antenna Interface
There is a GSM antenna pad named RF_ANT for M26.
Table 22: Pin Definition of the RF_ANT
4.1.1. Reference Design
The external antenna must be matched properly to achieve best performance, so the matching circuit is
necessary, the reference design for RF is shown as below.
M26_Hardware_Design Confidential / Released 56 / 80
Figure 40: Reference Design for GSM Antenna
GSM/GPRS Module Series
Type
Requirements
GSM850/EGSM900
Cable insertion loss <1dB
DCS1800/PCS1900
Cable insertion loss <1.5dB
Type
Requirements
Frequency Range
Depending by frequency band (s) provided by the network operator
VSWR
≤ 2
Gain (dBi)
1
Max Input Power (W)
50
Input Impedance (Ω)
50
Polarization Type
Vertical
Frequency
Max.
Min.
GSM850
33dBm±2dB
5dBm±5dB
EGSM900
33dBm±2dB
5dBm±5dB
DCS1800
30dBm±2dB
0dBm±5dB
M26 Hardware Design
M26 provides an RF antenna pad for antenna connection. The RF trace in host PCB connected to the
module RF antenna pad should be coplanar waveguide line or microstrip line, whose characteristic
impedance should be close to 50Ω. M26 comes with grounding pads which are next to the antenna pad in
order to give a better grounding. Besides, a π type match circuit is suggested to be used to adjust the RF
performance.
To minimize the loss on the RF trace and RF cable, take design into account carefully. The following table
shows the requirement on GSM antenna.
Table 23: Antenna Cable Requirements
Table 24: Antenna Requirements
4.1.2. RF Output Power
Table 25: The Module Conducted RF Output Power
M26_Hardware_Design Confidential / Released 57 / 80
GSM/GPRS Module Series
In GPRS 4 slots TX mode, the max output power is reduced by 2.5dB. This design conforms to the GSM
specification as described in section 13.16 of 3GPP TS 51.010-1.
PCS1900
30dBm±2dB
0dBm±5dB
Frequency
Receive Sensitivity
GSM850
< -109dBm
EGSM900
< -109dBm
DCS1800
< -109dBm
PCS1900
< -109dBm
Frequency
Receive
Transmit
ARFCH
GSM850
869~894MHz
824~849MHz
128~251
EGSM900
925~960MHz
880~915MHz
0~124, 975~1023
DCS1800
1805~1880MHz
1710~1785MHz
512~885
PCS1900
1930~1990MHz
1850~1910MHz
512~810
NOTE
M26 Hardware Design
4.1.3. RF Receiving Sensitivity
Table 26: The Module Conducted RF Receiving Sensitivity
4.1.4. Operating Frequencies
Table 27: The Module Operating Frequencies
M26_Hardware_Design Confidential / Released 58 / 80
GSM/GPRS Module Series
Pin Name
Pin No.
Description
BT_ANT
26
BT antenna pad
GND
27
Ground
M26 Hardware Design
4.1.5. RF Cable Soldering
Soldering the RF cable to RF pad of module correctly will reduce the loss on the path of RF, please refer
to the following example of RF soldering.
Figure 41: RF Soldering Sample
4.2. Bluetooth Antenna Interface
M26 supports Bluetooth interface. Bluetooth is a wireless technology that allows devices to communicate,
or transmit data or voice, wirelessly over a short distance. It is described as a short-range communication
technology intended to replace the cables connecting portable and/or fixed devices while maintaining high
level of security. Bluetooth is standardized as IEEE802.15 and operates in the 2.4 GHz range using RF
technology. Its data rates of up to 3Mbps.
M26 is fully compliant with Bluetooth specification 3.0. M26 supports profile including SPP and OPP.
The module provides a Bluetooth antenna pad named BT_ANT.
Table 28: Pin Definition of the BT_ANT
M26_Hardware_Design Confidential / Released 59 / 80
GSM/GPRS Module Series
Module
BT_ANT
0R
NM NM
M26 Hardware Design
The external antenna must be matched properly to achieve best performance, so the matching circuit is
necessary, the connection is recommended as in the following figure:
Figure 42: Reference Design for Bluetooth Antenna
There are some suggestions for placing components and RF trace lying for Bluetooth RF traces:
Antenna matching circuit should be closed to the antenna;
Keep the RF traces as 50Ω;
The RF traces should be kept far away from the high frequency signals and strong disturbing source.
M26_Hardware_Design Confidential / Released 60 / 80
GSM/GPRS Module Series
Parameter
Min.
Max.
Unit
VBAT
-0.3
+4.73
V
Peak Current of Power Supply
0 2 A
RMS Current of Power Supply (during one TDMA- frame)
0
0.7 A Voltage at Digital Pins
-0.3
3.08
V
Voltage at Analog Pins
-0.3
3.08
V
Voltage at Digital/analog Pins in Power Down Mode
-0.25
0.25
V
Parameter
Min.
Typ.
Max.
Unit
Normal Temperature
-35
+25
+80
℃
M26 Hardware Design
5 Electrical, Reliability and Radio
Characteristics
5.1. Absolute Maximum Ratings
Absolute maximum ratings for power supply and voltage on digital and analog pins of module are listed in
the following table:
Table 29: Absolute Maximum Ratings
5.2. Operating Temperature
The operating temperature is listed in the following table:
Table 30: Operating Temperature
M26_Hardware_Design Confidential / Released 61 / 80
GSM/GPRS Module Series
1)
When the module works within this temperature range, the deviation from the GSM specification may
occur. For example, the frequency error or the phase error will be increased.
Restricted Operation1)
-40 ~ -35
+80 ~ +85
℃
Storage Temperature
-45 +90
℃
Parameter
Description
Conditions
Min.
Typ.
Max.
Unit
VBAT
Supply voltage
Voltage must stay within the
min/max values, including
voltage drop, ripple, and spikes.
3.3
4.0
4.6
V
Voltage drop
during
transmitting
burst
Maximum power control level
on GSM850 and EGSM900.
400
mV
I
VBAT
Average supply
current
Power down mode
SLEEP mode @DRX=5
150
1.3
uA
mA
Minimum functionality mode
AT+CFUN=0
IDLE mode
SLEEP mode
AT+CFUN=4
IDLE mode
SLEEP mode
13
0.98
13
1.0
mA
mA
mA
mA
TALK mode
GSM850/EGSM9001)
DCS1800/PCS19002)
223/219
153/151
mA
mA
DATA mode, GPRS (3Rx, 2Tx)
GSM850/EGSM9001)
DCS1800/PCS19002)
363/393
268/257
mA
mA
DATA mode, GPRS (2 Rx, 3Tx)
GSM850/EGSM9001)
DCS1800/PCS19002)
506/546
366/349
mA
mA
NOTE
M26 Hardware Design
5.3. Power Supply Ratings
Table 31: The Module Power Supply Ratings
M26_Hardware_Design Confidential / Released 62 / 80
GSM/GPRS Module Series
1.
1)
Power control level PCL 5.
2.
2)
Power control level PCL 0.
3.
3)
Under the GSM850 and EGSM900 spectrum, the power of 1Rx and 4Tx has been reduced.
DATA mode, GPRS (4 Rx, 1Tx)
GSM850/EGSM9001)
DCS1800/PCS19002)
217/234
172/170
mA
mA
DATA mode, GPRS (1Rx, 4Tx)
GSM850/EGSM9001)
DCS1800/PCS19002)
458/4853)
462/439
mA
mA
Peak supply
current (during
transmission
slot)
Maximum power control level
on GSM850 and EGSM900.
1.6 2 A
Condition
Current Consumption
Voice Call
GSM850
@power level #5 <300mA, Typical 223mA
@power level #12, Typical 83mA
@power level #19, Typical 62mA
EGSM900
@power level #5 <300mA, Typical 219mA
@power level #12, Typical 83mA
@power level #19, Typical 63mA
DCS1800
@power level #0 <250mA, Typical 153mA
@power level #7, Typical 73mA
@power level #15, Typical 60mA
PCS1900
@power level #0 <250mA, Typical 151mA
@power level #7, Typical 76mA
@power level #15, Typical 61mA
GPRS Data
NOTE
M26 Hardware Design
5.4. Current Consumption
The values of current consumption are shown as below.
Table 32: The Module Current Consumption
M26_Hardware_Design Confidential / Released 63 / 80
GSM/GPRS Module Series
DATA Mode, GPRS ( 3 Rx, 2Tx ) CLASS 12
GSM850
@power level #5 <550mA, Typical 363mA
@power level #12, Typical 131mA
@power level #19, Typical 91mA
EGSM900
@power level #5 <550mA, Typical 393mA
@power level #12, Typical 132mA
@power level #19, Typical 92mA
DCS1800
@power level #0 <450mA, Typical 268mA
@power level #7, Typical 112mA
@power level #15, Typical 88mA
PCS1900
@power level #0 <450mA, Typical 257mA
@power level #7, Typical 119mA
@power level #15, Typical 89mA
DATA Mode, GPRS ( 2 Rx, 3Tx ) CLASS 12
GSM850
@power level #5 <640mA, Typical 506mA
@power level #12, Typical 159mA
@power level #19, Typical 99mA
EGSM900
@power level #5 <600mA, Typical 546mA
@power level #12, Typical 160mA
@power level #19, Typical 101mA
DCS1800
@power level #0 <490mA, Typical 366mA
@power level #7, Typical 131mA
@power level #15, Typical 93mA
PCS1900
@power level #0 <480mA, Typical 348mA
@power level #7, Typical 138mA
@power level #15, Typical 94mA
DATA Mode, GPRS ( 4 Rx,1Tx ) CLASS 12
GSM850
@power level #5 <350mA, Typical 216mA
@power level #12, Typical 103mA
@power level #19, Typical 83mA
EGSM900
@power level #5 <350mA, Typical 233mA
@power level #12, Typical 104mA
@power level #19, Typical 84mA
DCS1800
@power level #0 <300mA, Typical 171mA
@power level #7, Typical 96mA
@power level #15, Typical 82mA
PCS1900
@power level #0 <300mA, Typical 169mA
@power level #7, Typical 98mA
@power level #15, Typical 83mA
DATA Mode, GPRS ( 1 Rx, 4Tx ) CLASS 12
M26 Hardware Design
M26_Hardware_Design Confidential / Released 64 / 80
GSM/GPRS Module Series
GPRS Class 12 is the default setting. The module can be configured from GPRS Class 1 to Class 12.
Setting to lower GPRS class would make it easier to design the power supply for the module.
GSM850
@power level #5 <660mA, Typical 457mA
@power level #12, Typical 182mA
@power level #19, Typical 106mA
EGSM900
@power level #5 <660mA, Typical 484mA
@power level #12, Typical 187mA
@power level #19, Typical 109mA
DCS1800
@power level #0 <530mA, Typical 461mA
@power level #7, Typical 149mA
@power level #15, Typical 97mA
PCS1900
@power level #0 <530mA, Typical 439mA
@power level #7, Typical 159mA
@power level #15, Typical 99mA
Tested Point
Contact Discharge
Air Discharge
VBAT, GND
±5KV
±10KV
RF_ANT
±5KV
±10KV
TXD, RXD
±2KV
±4KV
Others
±0.5KV
±1KV
NOTE
M26 Hardware Design
5.5. Electro-static Discharge
Although the GSM engine is generally protected against Electro-static Discharge (ESD), ESD protection
precautions should still be emphasized. Proper ESD handling and packaging procedures must be applied
throughout the processing, handling and operation of any applications using the module.
The measured ESD values of module are shown as the following table:
Table 33: The ESD Endurance (Temperature: 25ºC , Humidity: 45%)
M26_Hardware_Design Confidential / Released 65 / 80
GSM/GPRS Module Series
M26 Hardware Design
6 Mechanical Dimensions
This chapter describes the mechanical dimensions of the module.
6.1. Mechanical Dimensions of Module
Figure 43: M26 Module Top and Side Dimensions (Unit: mm)
M26_Hardware_Design Confidential / Released 66 / 80
GSM/GPRS Module Series
M26 Hardware Design
Figure 44: M26 Module Bottom Dimensions (Unit: mm)
M26_Hardware_Design Confidential / Released 67 / 80
GSM/GPRS Module Series
1
14
23
36
1. The module should be kept about 3mm away from other components in the host PCB.
2. The circular test points with a radius of 1.75mm in the above recommended footprint should be
treated as keepout areas. (―keepout‖ means do not pour copper on the mother board).
NOTE
M26 Hardware Design
6.2. Recommended Footprint
Figure 45: Recommended Footprint (Unit: mm)
M26_Hardware_Design Confidential / Released 68 / 80
GSM/GPRS Module Series
M26 Hardware Design
6.3. Top View of the Module
Figure 46: Top View of the Module
6.4. Bottom View of the Module
Figure 47: Bottom View of the Module
M26_Hardware_Design Confidential / Released 69 / 80
GSM/GPRS Module Series
As plastic container cannot be subjected to high temperature, devices must be removed prior to high
temperature (125ºC ) bake. If shorter bake times are desired, refer to the IPC/JEDECJ-STD-033 for bake
procedure.
NOTE
M26 Hardware Design
7 Storage and Manufacturing
7.1. Storage
M26 module is distributed in a vacuum-sealed bag. The restriction for storage is shown as below.
Shelf life in the vacuum-sealed bag: 12 months at environments of <40ºC temperature and <90%RH.
After the vacuum-sealed bag is opened, devices that need to be mounted directly must be:
Mounted within 72 hours at the factory environment of ≤30ºC temperature and <60% RH.
Stored at <10% RH.
Devices require baking before mounting, if any circumstance below occurs.
When the ambient temperature is 23ºC ±5 ºC , humidity indication card shows the humidity is >10%
before opening the vacuum-sealed bag.
If ambient temperature is <30ºC and the humidity is <60%, the devices have not been mounted
during 72hours.
Stored at >10% RH.
If baking is required, devices should be baked for 48 hours at 125ºC ±5 ºC .
M26_Hardware_Design Confidential / Released 70 / 80
GSM/GPRS Module Series
Time(s)
50
100
150 200 250 300
50
100
150
200
250
160℃
200℃
217
0
70s~120s
40s~60s
Between 1~3℃/S
Preheat Heating Cooling
℃
s
Liquids
Temperature
M26 Hardware Design
7.2. Soldering
The squeegee should push the paste on the surface of the stencil that makes the paste fill the stencil
openings and penetrate to the PCB. The force on the squeegee should be adjusted so as to produce a
clean stencil surface on a single pass. To ensure the module soldering quality, the thickness of stencil at
the hole of the module pads should be 0.2 mm for M26.For more details, please refer to document [12]
It is suggested that peak reflow temperature is from 235ºC to 245ºC (for SnAg3.0Cu0.5 alloy). Absolute
max reflow temperature is 260ºC. To avoid damage to the module when it was repeatedly heated, it is
suggested that the module should be mounted after the first panel has been reflowed. The following
picture is the actual diagram which we have operated.
Figure 48: Ramp-Soak-Spike Reflow Profile
7.3. Packaging
The modules are stored in a vacuum-sealed bag which is ESD protected. It should not be opened until the
devices are ready to be soldered onto the application.
M26_Hardware_Design Confidential / Released 71 / 80
GSM/GPRS Module Series
M26 Hardware Design
7.3.1. Tape and Reel Packaging
The reel is 330mm in diameter and each reel contains 250 modules.
Figure 49: Tape and Reel Specification
Figure 50: Dimensions of Reel
M26_Hardware_Design Confidential / Released 72 / 80
GSM/GPRS Module Series
SN
Document Name
Remark
[1]
Quectel_M26_AT_Commands_Manual
AT commands manual
[2]
ITU-T Draft new recommendation V.25ter
Serial asynchronous automatic dialing
and control
[3]
GSM 07.07
Digital cellular telecommunications
(Phase 2+); AT command set for GSM
Mobile Equipment (ME)
[4]
GSM 07.10
Support GSM 07.10 multiplexing
protocol
[5]
GSM 07.05
Digital cellular telecommunications
(Phase 2+); Use of Data Terminal
Equipment – Data Circuit terminating
Equipment (DTE – DCE) interface for
Short Message Service (SMS) and
Cell Broadcast Service (CBS)
[6]
GSM 11.14
Digital cellular telecommunications
(Phase 2+); Specification of the SIM
Application Toolkit for the Subscriber
Identity module – Mobile Equipment
(SIM – ME) interface
[7]
GSM 11.11
Digital cellular telecommunications
(Phase 2+); Specification of the
Subscriber Identity module – Mobile
Equipment (SIM – ME) interface
[8]
GSM 03.38
Digital cellular telecommunications
(Phase 2+); Alphabets and
language-specific information
[9]
GSM 11.10
Digital cellular telecommunications
(Phase 2); Mobile Station (MS)
conformance specification; Part 1:
Conformance specification
M26 Hardware Design
8 Appendix A Reference
Table 34: Related Documents
M26_Hardware_Design Confidential / Released 73 / 80
GSM/GPRS Module Series
[10]
GSM_UART_Application_Note
UART port application note
[11]
GSM_EVB_User_Guide
GSM EVB user guide
[12]
Module_Secondary_SMT_User_Guide
Module secondary SMT user guide
[13]
Quectel_GSM_Module_Digital_IO_Application_Note
GSM Module Digital IO Application
Note
Abbreviation
Description
ADC
Analog-to-Digital Converter
AMR
Adaptive Multi-Rate
ARP
Antenna Reference Point
ASIC
Application Specific Integrated Circuit
BER
Bit Error Rate
BOM
Bill of Material
BT
Bluetooth
BTS
Base Transceiver Station
CHAP
Challenge Handshake Authentication Protocol
CS
Coding Scheme
CSD
Circuit Switched Data
CTS
Clear to Send
DAC
Digital-to-Analog Converter
DRX
Discontinuous Reception
DSP
Digital Signal Processor
DCE
Data Communications Equipment (typically module)
DTE
Data Terminal Equipment (typically computer, external controller)
DTR
Data Terminal Ready
M26 Hardware Design
Table 35: Terms and Abbreviations
M26_Hardware_Design Confidential / Released 74 / 80
GSM/GPRS Module Series
DTX
Discontinuous Transmission
EFR
Enhanced Full Rate
EGSM
Enhanced GSM
EMC
Electromagnetic Compatibility
ESD
Electrostatic Discharge
ETS
European Telecommunication Standard
FCC
Federal Communications Commission (U.S.)
FDMA
Frequency Division Multiple Access
FR
Full Rate
GMSK
Gaussian Minimum Shift Keying
GPRS
General Packet Radio Service
GSM
Global System for Mobile Communications
G.W
Gross Weight
HR
Half Rate
I/O
Input/Output
IC
Integrated Circuit
IMEI
International Mobile Equipment Identity
IOmax
Maximum Output Load Current
kbps
Kilo Bits Per Second
LED
Light Emitting Diode
Li-Ion
Lithium-Ion
MO
Mobile Originated
MOQ
Minimum Order Quantity
MP
Manufacture Product
MS
Mobile Station (GSM engine)
M26 Hardware Design
M26_Hardware_Design Confidential / Released 75 / 80
GSM/GPRS Module Series
MT
Mobile Terminated
N.W
Net Weight
PAP
Password Authentication Protocol
PBCCH
Packet Switched Broadcast Control Channel
PCB
Printed Circuit Board
PDU
Protocol Data Unit
PPP
Point-to-Point Protocol
RF
Radio Frequency
RMS
Root Mean Square (value)
RTC
Real Time Clock
RX
Receive Direction
SIM
Subscriber Identification Module
SMS
Short Message Service
TDMA
Time Division Multiple Access
TE
Terminal Equipment
TX
Transmitting Direction
UART
Universal Asynchronous Receiver & Transmitter
URC
Unsolicited Result Code
USSD
Unstructured Supplementary Service Data
VSWR
Voltage Standing Wave Ratio
VOmax
Maximum Output Voltage Value
VOnorm
Normal Output Voltage Value
VOmin
Minimum Output Voltage Value
VIHmax
Maximum Input High Level Voltage Value
VIHmin
Minimum Input High Level Voltage Value
M26 Hardware Design
M26_Hardware_Design Confidential / Released 76 / 80
GSM/GPRS Module Series
VILmax
Maximum Input Low Level Voltage Value
VILmin
Minimum Input Low Level Voltage Value
VImax
Absolute Maximum Input Voltage Value
VInorm
Absolute Normal Input Voltage Value
VImin
Absolute Minimum Input Voltage Value
VOHmax
Maximum Output High Level Voltage Value
VOHmin
Minimum Output High Level Voltage Value
VOLmax
Maximum Output Low Level Voltage Value
VOLmin
Minimum Output Low Level Voltage Value
Phonebook Abbreviations
LD
SIM Last Dialing phonebook (list of numbers most recently dialed)
MC
Mobile Equipment list of unanswered MT Calls (missed calls)
ON
SIM (or ME) Own Numbers (MSISDNs) list
RC
Mobile Equipment list of Received Calls
SM
SIM phonebook
M26 Hardware Design
M26_Hardware_Design Confidential / Released 77 / 80
GSM/GPRS Module Series
Scheme
Code
Rate
USF
Pre-coded
USF
Radio Block
excl.USF and
BCS
BCS
Tail
Coded
Bits
Punctured
Bits
Data
Rate
Kb/s
CS-1
1/2 3 3
181
40 4 456
0
9.05
CS-2
2/3 3 6
268
16 4 588
132
13.4
CS-3
3/4 3 6
312
16 4 676
220
15.6
CS-4
1 3 12
428
16 - 456
-
21.4
Rate 1/2 convolutional coding
Puncturing
456 bits
USF
BCS
Radio Block
M26 Hardware Design
9 Appendix B GPRS Coding Scheme
Four coding schemes are used in GPRS protocol. The differences between them are shown in the
following table.
Table 36: Description of Different Coding Schemes
Radio block structure of CS-1, CS-2 and CS-3 is shown as the figure below.
Figure 51: Radio Block Structure of CS-1, CS-2 and CS-3
M26_Hardware_Design Confidential / Released 78 / 80
GSM/GPRS Module Series
Block
Code
No coding
456 bits
USF
BCS
Radio Block
M26 Hardware Design
Radio block structure of CS-4 is shown as the following figure.
Figure 52: Radio Block Structure of CS-4
M26_Hardware_Design Confidential / Released 79 / 80
GSM/GPRS Module Series
Multislot Class
Downlink Slots
Uplink Slots
Active Slots
1 1 1 2 2 2 1 3 3 2 2 3 4 3 1 4 5 2 2
4
6 3 2
4
7 3 3 4 8 4 1 5 9 3 2 5 10 4 2 5 11 4 3
5
12 4 4
5
M26 Hardware Design
10 Appendix C GPRS Multi-slot Class
Twenty-nine classes of GPRS multi-slot modes are defined for MS in GPRS specification. Multi-slot
classes are product dependant, and determine the maximum achievable data rates in both the uplink and
downlink directions. Written as 3+1 or 2+2, the first number indicates the amount of downlink timeslots,
while the second number indicates the amount of uplink timeslots. The active slots determine the total
number of slots the GPRS device can use simultaneously for both uplink and downlink communications.
The description of different multi-slot classes is shown in the following table.
Table 37: GPRS Multi-slot Classes
M26_Hardware_Design Confidential / Released 80 / 80
GSM/GPRS Module Series
M26 Hardware Design
11 FCC Warning
Any Changes or modifications not expressly approved by the party responsible for compliance could
void the user’s authority to operate the equipment.
This device complies with part 15 of the FCC Rules. Operation is subject to the following two conditions:
(1) This device may not cause harmful interference, and (2) this device must accept any interference
received, including interference that may cause undesired operation.
To satisfy FCC RF Exposure requirements for this transmission devices, a separation distance of 20cm or
more should be maintained between the antenna of this device and persons during operation. To ensure
compliance, operation at closer than this distance is not recommended. The antenna(s) used for this
transmitter must not be co-located or operating in conjunction with any other antenna or transmitter.
Changes or modifications not expressly approved by the party responsible for compliance could void the
user's authority to operate the equipment.
The modular transmitter must be equipped with either a permanently affixed label or must be capable of
electronically displaying its FCC identification number：
(A) If using a permanently affixed label, the modular transmitter must be labeled with its own FCC
identification number, and, if the FCC identification number is not visible when the module is installed inside
another device, then the outside of the device into which the module is installed must also display a label
referring to the enclosed module. This exterior label can use wording such as the following: “Contains
Transmitter Module FCC ID:XMR201604M26.” Any similar wording that expresses the same meaning may
be used. The Grantee may either provide such a label, an example of which must be included in the
application for equipment authorization, or, must provide adequate instructions along with the module which
explain this requirement. In the latter case, a copy of these instructions must be included in the application
for equipment authorization.
M26_Hardware_Design Confidential / Released 81 / 81
Loading...