Quectel Wireless Solutions 201403GC65 User Manual
GC65 Hardware Design
GSM/GPRS Module Series
Rev. GC65_Hardware_Design_V2.0
Date: 2014-01-09
www.quectel.com
GC65 Hardware Design
GSM/GPRS Module Series
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GC65 Hardware Design
About the Document
History
Revision Date Author Description
1.0 2013-12-09 King HAO Initial
GSM/GPRS Module Series
2.0 2014-01-09 King HAO
1. Update Figure 2：Pin assignment.
2. Modified the mechanical dimensions and the
recommended footprint of the module in Chapter 6.
3. Update the function of SIM card detection.
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Contents
About the Document ................................................................................................................................... 2
Contents ....................................................................................................................................................... 3
Table Index ................................................................................................................................................... 5
Figure Index ................................................................................................................................................. 6
1 Introduction .......................................................................................................................................... 8
1.1. Safety Information ................................................................................................................... 8
2 Product Concept ................................................................................................................................ 10
2.1. General Description ............................................................................................................... 10
2.2. Directives and Standards ...................................................................................................... 10
2.3. Key Features ......................................................................................................................... 11
2.4. Functional Diagram ............................................................................................................... 13
2.5. Evaluation Board ................................................................................................................... 14
3 Application Interface ......................................................................................................................... 15
3.1. Pin of Module ......................................................................................................................... 16
3.2. Operating Modes ................................................................................................................... 21
3.3. Power Supply ........................................................................................................................ 22
3.4. Power On and Down Scenarios ............................................................................................ 24
3.5. Power Saving Technology ..................................................................................................... 31
3.6. RTC Backup .......................................................................................................................... 32
3.7. Serial Interfaces ..................................................................................................................... 34
2.2.1. FCC Statement ............................................................................................................... 10
2.2.2. FCC Radiation Exposure Statement .............................................................................. 11
3.1.1. Pin Assignment .............................................................................................................. 16
3.1.2. Pin Description ............................................................................................................... 17
3.3.1. Power Features of Module ............................................................................................. 22
3.3.2. Decrease Supply Voltage Drop ...................................................................................... 22
3.3.3. Reference Design for Power Supply .............................................................................. 23
3.3.4. Monitor Power Supply .................................................................................................... 24
3.4.1. Power On ....................................................................................................................... 24
3.4.2. Power Down ................................................................................................................... 26
3.4.2.1. Power Down Module by the PWRKEY Pin ....................................................... 27
3.4.2.2. Power Down Module by AT Command ............................................................. 28
3.4.2.3. Over-voltage or Under-voltage Automatic Shutdown ........................................ 28
3.4.2.4. Emergency Shutdown by EMERG_OFF Pin .................................................... 29
3.4.3. Restart ............................................................................................................................ 30
3.5.1. Minimum Functionality Mode ......................................................................................... 31
3.5.2. Sleep Mode .................................................................................................................... 31
3.5.3. Wake Up Module from Sleep Mode ............................................................................... 32
3.5.4. Summary of State Transition .......................................................................................... 32
3.7.1. UART Port ...................................................................................................................... 36
3.7.1.1. The Features of UART Port ............................................................................... 36
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3.7.1.2. The Connection of UART .................................................................................. 37
3.7.2. Debug and Upgrade Port ............................................................................................... 38
3.7.3. UART Application ........................................................................................................... 39
3.8. Audio Interfaces ..................................................................................................................... 41
3.8.1. Decrease TDD Noise and Other Noises ........................................................................ 42
3.8.2. Microphone Interfaces Design ....................................................................................... 43
3.8.3. Receiver Interface Design .............................................................................................. 44
3.8.4. Earphone Interface Design ............................................................................................ 46
3.8.5. Audio Characteristics ..................................................................................................... 46
3.9. SIM Card Interface ................................................................................................................ 47
3.9.1. SIM Card Application ...................................................................................................... 47
3.9.2. SIM Cassette .................................................................................................................. 49
3.10. PCM Interface ........................................................................................................................ 52
3.11. Behaviors of the RI ................................................................................................................ 52
3.12. Network Status Indication ...................................................................................................... 53
4 Antenna Interface ............................................................................................................................... 55
4.1. RF Reference Design ............................................................................................................ 55
4.2. RF Output Power ................................................................................................................... 56
4.3. RF Receiving Sensitivity ........................................................................................................ 56
4.4. Operating Frequencies .......................................................................................................... 57
4.5. RF Cable Soldering ............................................................................................................... 57
5 Electrical, Reliability and Radio Characteristics ............................................................................ 58
5.1. Absolute Maximum Ratings................................................................................................... 58
5.2. Operating Temperature ......................................................................................................... 59
5.3. Power Supply Ratings ........................................................................................................... 59
5.4. Current Consumption ............................................................................................................ 60
5.5. Electro-static Discharge ........................................................................................................ 61
6 Mechanical Dimensions .................................................................................................................... 63
6.1. Mechanical Dimensions of Module ....................................................................................... 63
6.2. Recommended Footprint ....................................................................................................... 65
6.3. Top View of the Module ......................................................................................................... 66
6.4. Bottom View of the Module ................................................................................................... 66
7 Storage and Manufacturing .............................................................................................................. 67
7.1. Storage .................................................................................................................................. 67
7.2. Soldering ............................................................................................................................... 68
7.3. Packaging .............................................................................................................................. 69
7.3.1. Tape and Reel Packaging .............................................................................................. 69
8 Appendix A Reference ....................................................................................................................... 71
9 Appendix B GPRS Coding Scheme ................................................................................................. 75
10 Appendix C GPRS Multi-slot Class .................................................................................................. 77
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Table Index
TABLE 1: MODULE KEY FEATURES ................................................................................................................ 11
TABLE 2: CODING SCHEMES AND MAXIMUM NET DATA RATES OVER AIR INTERFACE ........................ 13
TABLE 3: PIN DESCRIPTION ........................................................................................................................... 17
TABLE 4: OVERVIEW OF OPERATING MODES ............................................................................................. 21
TABLE 5: SUMMARY OF STATE TRANSITION ............................................................................................... 32
TABLE 6: LOGIC LEVELS OF THE UART INTERFACES ................................................................................ 35
TABLE 7: PIN DEFINITION OF THE UART INTERFACES .............................................................................. 35
TABLE 8: PIN DEFINITION OF AUDIO INTERFACE ....................................................................................... 41
TABLE 9: TYPICAL ELECTRET MICROPHONE CHARACTERISTICS ........................................................... 46
TABLE 10: TYPICAL AUDIO OUTPUT CHARACTERISTICS .......................................................................... 46
TABLE 11: PIN DEFINITION OF THE SIM INTERFACE .................................................................................. 47
TABLE 12: PIN DESCRIPTION OF AMPHENOL SIM CARD HOLDER ........................................................... 50
TABLE 13: PIN DESCRIPTION OF MOLEX SIM CARD HOLDER .................................................................. 51
TABLE 14: BEHAVIOURS OF THE RI .............................................................................................................. 52
TABLE 15: WORKING STATE OF THE NETLIGHT .......................................................................................... 53
TABLE 16: PIN DEFINITION OF THE RF_ANT ................................................................................................ 55
TABLE 17: THE MODULE CONDUCTED RF OUTPUT POWER .................................................................... 56
TABLE 18: THE MODULE CONDUCTED RF RECEIVING SENSITIVITY ....................................................... 56
TABLE 19: THE MODULE OPERATING FREQUENCIES ................................................................................ 57
TABLE 20: ABSOLUTE MAXIMUM RATINGS .................................................................................................. 58
TABLE 21: OPERATING TEMPERATURE ........................................................................................................ 59
TABLE 22: THE MODULE POWER SUPPLY RATINGS .................................................................................. 59
TABLE 23: THE MODULE CURRENT CONSUMPTION .................................................................................. 60
TABLE 24: THE ESD ENDURANCE (TEMPERATURE: 25℃, HUMIDITY: 45 %) ........................................... 62
TABLE 25: RELATED DOCUMENTS ................................................................................................................ 71
TABLE 26: TERMS AND ABBREVIATIONS ...................................................................................................... 72
TABLE 27: DESCRIPTION OF DIFFERENT CODING SCHEMES .................................................................. 75
TABLE 28: GPRS MULTI-SLOT CLASSES ...................................................................................................... 77
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Figure Index
FIGURE 1: MODULE FUNCTIONAL DIAGRAM ............................................................................................... 14
FIGURE 2: PIN ASSIGNMENT ......................................................................................................................... 16
FIGURE 3: VOLTAGE DROP DURING TRANSMITTING ................................................................................. 22
FIGURE 4: REFERENCE CIRCUIT FOR THE VBAT INPUT ........................................................................... 23
FIGURE 5: REFERENCE CIRCUIT FOR POWER SUPPLY ............................................................................ 24
FIGURE 6: REFERENCE DIAGRAM FOR SWITCHING POWER CONVERTER ........................................... 24
FIGURE 7: TURN ON THE MODULE WITH AN OC DRIVER .......................................................................... 25
FIGURE 8: TURN ON THE MODULE WITH A BUTTON .................................................................................. 25
FIGURE 9: TURN-ON TIMING .......................................................................................................................... 26
FIGURE 10: TURN-OFF TIMING ...................................................................................................................... 27
FIGURE 11: AN OC DRIVER FOR EMERG_OFF ............................................................................................ 29
FIGURE 12: REFERENCE CIRCUIT FOR EMERG_OFF BY BUTTON .......................................................... 29
FIGURE 13: TIMING OF RESTARTING SYSTEM ............................................................................................ 30
FIGURE 14: TIMING OF RESTARTING SYSTEM AFTER EMERGENCY SHUTDOWN ................................ 30
FIGURE 15: RTC SUPPLIED FROM A NON-CHARGEABLE BATTERY ......................................................... 33
FIGURE 16: RTC SUPPLIED FROM A RECHARGEABLE BATTERY ............................................................. 33
FIGURE 17: RTC SUPPLIED FROM A CAPACITOR ....................................................................................... 33
FIGURE 18: CHARGING CHARACTERISTICS OF SEIKO’S XH414H-IV01E ................................................ 34
FIGURE 19: REFERENCE DESIGN FOR FULL-FUNCTION UART ................................................................ 37
FIGURE 20: REFERENCE DESIGN FOR UART PORT ................................................................................... 38
FIGURE 21: REFERENCE DESIGN FOR UART PORT WITH HARDWARE FLOW CONTROL .................... 38
FIGURE 22: THE CONNECTION OF FIRMWARE DEBUGGING AND UPGRADE......................................... 39
FIGURE 23: LEVEL MATCH DESIGN FOR 3.3V SYSTEM .............................................................................. 39
FIGURE 24: LEVEL MATCH DESIGN FOR 5V SYSTEM ................................................................................. 40
FIGURE 25: LEVEL MATCH DESIGN FOR RS-232 ......................................................................................... 41
FIGURE 26: REFERENCE DESIGN FOR AIN1&AIN2 ..................................................................................... 43
FIGURE 27: REFERENCE RECEIVER INTERFACE DESIGN OF AOUT1 ..................................................... 44
FIGURE 28: SPEAKER INTERFACE WITH AMPLIFIER CONFIGURATION OF AOUT1................................ 44
FIGURE 29: REFERENCE RECEIVER INTERFACE DESIGN OF AOUT2 ..................................................... 45
FIGURE 30: SPEAKER INTERFACE WITH AMPLIFIER CONFIGURATION OF AOUT2................................ 45
FIGURE 31: EARPHONE INTERFACE DESIGN .............................................................................................. 46
FIGURE 32: REFERENCE CIRCUIT FOR 8-PIN SIM CARD HOLDER .......................................................... 48
FIGURE 33: REFERENCE CIRCUIT FOR 6-PIN SIM CARD HOLDER .......................................................... 49
FIGURE 34: AMPHENOL C707 10M006 512 2 SIM CARD HOLDER .............................................................. 50
FIGURE 35: MOLEX 91228 SIM CARD HOLDER ............................................................................................ 51
FIGURE 36: RI BEHAVIOUR OF VOICE CALLING AS A RECEIVER ............................................................. 52
FIGURE 37: RI BEHAVIOUR AS A CALLER ..................................................................................................... 53
FIGURE 38: RI BEHAVIOUR OF URC OR SMS RECEIVED ........................................................................... 53
FIGURE 39: REFERENCE DESIGN FOR NETLIGHT ..................................................................................... 54
FIGURE 40: REFERENCE DESIGN FOR RF .................................................................................................. 55
FIGURE 41: RF SOLDERING SAMPLE ........................................................................................................... 57
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FIGURE 42: GC65 MODULE TOP AND SIDE DIMENSIONS (UNIT: MM) ....................................................... 63
FIGURE 43: GC65 MODULE BOTTOM DIMENSIONS (UNIT: MM) ................................................................ 64
FIGURE 44: RECOMMENDED FOOTPRINT (UNIT: MM) ................................................................................ 65
FIGURE 45: TOP VIEW OF THE MODULE ...................................................................................................... 66
FIGURE 46: BOTTOM VIEW OF THE MODULE .............................................................................................. 66
FIGURE 47: THE PICTURE OF PRINTING PASTE ......................................................................................... 68
FIGURE 48: RAMP-SOAK-SPIKE REFLOW PROFILE .................................................................................... 69
FIGURE 49: DIMENSIONS OF TAPE ............................................................................................................... 70
FIGURE 50: DIMENSIONS OF REEL ............................................................................................................... 70
FIGURE 51: RADIO BLOCK STRUCTURE OF CS-1, CS-2 AND CS-3 ........................................................... 75
FIGURE 52: RADIO BLOCK STRUCTURE OF CS-4 ....................................................................................... 76
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GC65 Hardware Design
GSM/GPRS Module Series
1
This document defines the GC65 module and describes its hardware interface which are connected with
your application and the air interface.
This document can help you quickly understand module interface specifications, electrical and
mechanical details. Associated with application notes and user guide, you can use GC65 module to
design and set up mobile applications easily.
Introduction
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 GC65 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 your failure to comply with these precautions.
Full attention must be given to driving at all times in order to reduce the risk of an
accident. Using a mobie while driving (even with a handsfree kit) cause distraction
and can lead to an accident. You must comply with laws and regulations restrcting
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 Flight
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.
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GSM 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.
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2
Product Concept
2.1. General Description
GC65 is a Quad-band GSM/GPRS engine that works at frequencies of GSM850MHz, GSM900MHz,
DCS1800MHz and PCS1900MHz. The GC65 features GPRS multi-slot class 10 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 19mm×16.9mm×2.35mm, 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.
GC65 is an SMD type module, which can be easily embedded into applications through its 44-pin pads. It
provides abundant hardware interfaces like Audio and UART Interface.
Designed with power saving technique, the current consumption of GC65 is as low as 1.3mA in sleep
mode when DRX is 5.
GC65 is integrated with Internet service protocols, such as TCP/UDP, HTTP and PPP. Extended AT
commands have been developed for you to use these Internet service protocols easily.
The module fully complies with the RoHS directive of the European Union.
2.2. Directives and Standards
The GC10 module is designed to comply with the FCC statements. FCC ID: XMR201403GC65
The Host system using GC65, should have label indicated FCC ID: XMR201403GC65.
2.2.1. FCC Statement
1. This device complies with Part 15 of the FCC rules. Operation is subject to the following conditions:
a) This device may not cause harmful interference.
b) This device must accept any interference received, including interference that may cause undesired
operation.
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2. Changes or modifications not expressly approved by the party responsible for compliance could void
the user’s authority to operate the equipment.
2.2.2. FCC Radiation Exposure Statement
This equipment complies with FCC radiation exposure limits set forth for an uncontrolled environment.
This equipment should be installed and operated with minimum distance 20cm between the radiator and
your body as well as kept minimum 20cm from radio antenna depending on the Mobile status of this
module usage. This module should NOT be installed and operating simultaneously with other radio.
The manual of the host system, which uses GC65, must include RF exposure warning statement to
advice user should keep minimum 20cm from the radio antenna of GC65 module depending on the
Mobile status.
Note: If a portable device (such as PDA) uses GC65 module, the device needs to do permissive change
and SAR testing.
The following list of antenna is indicating the maximum permissible antenna gain.
Part Number
3R007A
Frequency
Range (MHz)
PCS1900:1850~1990
GSM850:824-894
Peak Gain
XZ-V)
1 dBi typ. 1 dBi typ. 3 max 50Ω
Average Gain
VSWR Impedance
XZ-V)
2.3. Key Features
The following table describes the detailed features of GC65 module.
Table 1: Module Key Features
Feature Implementation
Power Supply
Power Saving
Frequency Bands
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Single supply voltage: 3.3V~4.6V
Typical supply voltage: 4.0V
Typical power consumption in sleep mode: 1.3 mA@ DRX=5
1.1 mA@ DRX=9
Quad-band: GSM850/GSM900/DCS1800/PCS1900
The module can search these frequency bands automatically
The frequency bands can be set by AT command
GSM/GPRS Module Series
GC65 Hardware Design
Compliant to GSM Phase 2/2+
Transmitting Power
GPRS Connectivity
Class 4 (2W) at GSM850/GSM900
Class 1 (1W) at DCS1800/PCS1900
GPRS multi-slot class 10
GPRS mobile station class B
Normal operation: -35°C~ +80°C
Temperature Range
Restricted operation: -40°C ~ -35°C and +80°C ~ +85°C 1)
Storage temperature: -45°C ~ +90°C
GPRS data downlink transfer: max. 85.6kbps
GPRS data uplink transfer: max. 42.8kbps
DATA GPRS
Coding scheme: CS-1, CS-2, CS-3 and CS-4
Internet service protocols TCP/UDP, PPP, HTTP
Support Packet Broadcast Control Channel (PBCCH)
USSD Support Unstructured Supplementary Service Data
SMS
MT/MO, Text and PDU mode
SMS storage: SIM card
SIM Interface Support SIM card: 1.8V/3.0V
Speech codec modes:
Half Rate (ETS 06.20)
Full Rate (ETS 06.10)
Audio Features
Enhanced Full Rate (ETS 06.50/06.60/06.80)
Echo Suppression
Echo Cancellation
Noise Reduction
UART Port:
Seven lines on UART port interface
Used for AT command, GPRS data
Support fixed baud rate from 2400bps to 460800bps
UART Interfaces
Support autobauding from 4800bps to 115200bps
Debug Port:
Two lines on debug port interface DBG_TXD and DBG_RXD
Used for firmware debugging and log output
Used for firmware upgrade
The baud rate is fixed at 921600bps
Phonebook Management Support phonebook types: SM/ON/FD/LD
SIM Application Toolkit Support SAT class 3, GSM 11.14 Release 99
Real Time Clock Supported
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Physical Characteristics
Size: 19±0.15×16.9±0.15×2.35±0.2mm
Weight: Approx.1.3g
Firmware Upgrade Firmware upgrade via debug port
Antenna Interface Connected to antenna pad with 50 Ohm impedance control
NOTE
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.
Table 2: Coding Schemes and Maximum Net Data Rates over Air Interface
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
2.4. Functional Diagram
The following figure shows a block diagram of GC65 and illustrates the major functional parts.
Radio frequency part
Power management
Memory
The peripheral interface
—Power supply
—Turn-on/off interface
—UART interfaces
—Audio interfaces
—SIM interface
—PCM interface
—RTC interface
—RF interface
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Figure 1: Module Functional Diagram
2.5. Evaluation Board
In order to help you to develop applications with GC65, Quectel supplies an evaluation board (EVB) with
RS-232 to USB cable, power adapter, antenna, firmware upgrade cable (UART to USB cable) and other
peripherals to control or test the module. For details, please refer to the document [11].
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3
The module adopts 44-pin pads with LCC package. The following chapters provide detailed descriptions
about these pins below.
Power supply (Please refer to chapter 3.3)
Power on/down (Please refer to chapter 3.4)
Power saving technology (Please refer to chapter 3.5)
RTC (Please refer to chapter 3.6)
Serial interfaces (Please refer to chapter 3.7)
Audio interfaces (Please refer to chapter 3.8)
SIM interface (Please refer to chapter 3.9)
PCM interface (Please refer to chapter 3.10)
Application Interface
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3.1. Pin of Module
3.1.1. Pin Assignment
Figure 2: Pin Assignment
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3.1.2. Pin Description
Table 3: Pin Description
Power Supply
Pin Name
Pin
NO.
I/O Description DC Characteristics Comment
VBAT 33,34 I
VRTC 13 I/O
VDD_EXT 29 O
Main power supply of
module:
VBAT=3.3V~4.6V
Power supply for RTC
when VBAT is not
supplied for the system.
Charging for backup
battery or golden
capacitor when the VBAT
is applied.
Supply 3.0V voltage for
external circuit.
Vmax= 4.6V
Vmin=3.3V
Vnorm=4.0V
VImax=3.3V
VImin=2.0V
VInorm=2.8V
VOmax=2.9V
VOmin=2.7V
VOnorm=2.8V
Iout(max)=1.35mA
Iin=70uA
Vmax=3.1V
Vmin=2.9V
Vnorm=3.0V
Imax=20mA
Make sure that supply
sufficient current in a
transmitting burst
typically rises to 1.6A.
Recommended to be
connected to a backup
battery or a golden
capacitor. If unused,
keep this pin open.
Recommend to add a
2.2 or 4.7uF bypass
capacitor, when using
this pin for power
supply. If unused,
keep this pin open.
GND
Turn on/off
Pin Name
PWRKEY 5 I
Emergency Shutdown
Pin Name
32,35,
36,37,
39
Pin
NO.
Pin
NO.
Ground
I/O Description DC Characteristics Comment
Power on/off key.
PWRKEY should be
pulled down for a
moment to turn on or
VILmax=2.0V
VIHmin=2.3V
VImax=3.3V
Recommend to add an
OC driver circuit to
control this pin.
turn off the system.
I/O Description DC Characteristics Comment
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VOHmax=
GSM/GPRS Module Series
GC65 Hardware Design
Emergency off. Pulled
EMERG_
OFF
40 I
down for at least 10ms,
which will turn off the
module in case of
emergency. Use it only
when shutdown via
PWRKEY or AT
command cannot be
VILmax=
0.3×VDD_EXT
VIHmin=
0.7×VDD_EXT
Pulled up to VDD_EXT
internally. OC/OD
driver required in
cellular device
application. If unused,
keep this pin open.
achieved.
Module Indicator
Pin Name
Pin
NO.
I/O Description DC Characteristics Comment
NETLIGHT 14 O Network status indication
Audio Interfaces
Pin Name
MIC1P
MIC1N
SPK1P
SPK1N
Pin
NO.
I/O Description DC Characteristics Comment
19,20 I
21,22 O
Channel 1 positive and
negative voice input
Channel 1 positive and
negative voice output
VOLmin=0V
VOLmax=
0.3×VDD_EXT
VOHmin=
0.7×VDD_EXT
VDD_EXT
If unused, keep this
pin open.
Main audio channel.
Recommended to add
ESD protection
components at the
MIC1P/N lines. If
unused, keep these
pins open.
MIC2P
MIC2N
17,18 I
SPK2P 16 O
AGND 15 Audio analog ground.
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Channel 2 positive and
negative voice input
Channel 2 single-ended
voice output
For Audio DC
characteristics refer
to Chapter 3.9.
Auxiliary audio
channel.
Recommended to add
ESD protection
components at the
MIC2P/N lines. If
unused, keep these
pins open.
Separate ground
connection for external
audio circuits.
GSM/GPRS Module Series
GC65 Hardware Design
UART Port
Pin Name
Pin
NO.
I/O Description DC Characteristics Comment
RI 6 O Ring indication
DTR 7
I
Data terminal ready
DCD 8 O Data carrier detection
TXD 9 O Transmit data
RXD 10 I Receive data
RTS 11 I Request to send
CTS 12 O Clear to send
Debug Port
Pin Name
Pin
NO.
I/O Description DC Characteristics Comment
VILmin=0V
VILmax=
0.3×VDD_EXT
VIHmin=
0.7×VDD_EXT
VIHmax=
VDD_EXT
VOLmin=0V
VOLmax=
0.3×VDD_EXT
VOHmin=
0.7×VDD_EXT
VOHmax=
VDD_EXT
If only use TXD, RXD
and GND to
communicate,
recommended
connecting RTS to
GND via a 0R resistor
and keeping other pins
open.
DBG_TXD 31 O
DBG_RXD 30 I
SIM Interface
Pin Name
SIM_VDD 23 O
Pin
NO.
I/O Description DC Characteristics Comment
Used for firmware
debugging and upgrade.
The baud rate is fixed at
921600bps.
Power supply for SIM
card
VILmin=0V
VILmax=
0.3×VDD_EXT
VIHmin=
0.7×VDD_EXT
VIHmax=
VDD_EXT
VOLmin=0V
VOLmax=
0.3×VDD_EXT
VOHmin=
0.7×VDD_EXT
VOHmax=
VDD_EXT
The voltage can be
selected by software
automatically. Either
1.8V or 3V.
If unused, keep these
pins open.
All signals of SIM
interface should be
protected against ESD
with a TVS diode
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GSM/GPRS Module Series
GC65 Hardware Design
SIM_DATA 24 O SIM data
SIM_ RST 25 I/O SIM reset
SIM_CLK 26 O SIM clock
SIM_GND 27 SIM ground
VILmin=0V
VILmax=
SIM_
PRESENCE
28
I
SIM card detection
0.3×VDD_EXT
VIHmin=
0.7×VDD_EXT
VIHmax=
VDD_EXT
PCM Interface
Pin Name
Pin
NO.
I/O Description DC Characteristics Comment
VILmin=0V
PCM_ IN 1 I PCM data input
VILmax=
0.3×VDD_EXT
VIHmin=
0.7×VDD_EXT
VIHmax=
VDD_EXT
PCM_SYNC 2
PCM frame
O
synchronization
VOLmin=0V
PCM_ OUT 3 O PCM data output
VOLmax=
0.3×VDD_EXT
VOHmin=
0.7×VDD_EXT
PCM_ CLK 4 O PCM clock
VOHmax=
VDD_EXT
array. Maximum trace
length is 100mm from
the module pad to SIM
card holder.
SIM_PRESENCE
must be pulled up by
an external resistor
when SIM card
detection function is
used.
PCM function is not
supported at present.
If unused, keep these
pins open.
RF Interface
Pin Name
RF_ANT 38 I/O RF antenna pad Impedance of 50Ω
Pin
NO.
I/O Description DC Characteristics Comment
Please refer to
Chapter 4
Other Interface
Pin Name
RESERVED
Pin
NO.
41,42,
43,44
I/O Description DC Characteristics Comment
Please keep these
pins open.
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GSM/GPRS Module Series
GC65 Hardware Design
3.2. Operating Modes
The table below briefly summarizes the various operating modes in the following chapters.
Table 4: Overview of Operating Modes
Mode Function
The module will automatically go into sleep mode if DTR is
set to high level and there is no interrupt (such as GPIO
GSM/GPRS
Sleep
GSM Idle
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.
Software is active. The module has registered to the GSM
network, and the module is ready to send and receive
GSM data.
Normal Operation
Mode
Power Down Mode
GSM connection is ongoing. In this mode, the power
GSM Talk
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.
The module is registered to GPRS network, but no GPRS
GPRS Standby
PDP context is active. The SGSN knows the Routing Area
where the module is located at.
The PDP context is active, but no data transfer is ongoing.
GPRS Ready
The module is ready to receive or send GPRS data. The
SGSN knows the cell where the module is located at.
There is GPRS data in transfer. In this mode, power
GPRS Data
consumption is decided by the PCL, working RF band and
GPRS multi-slot configuration.
Normal shutdown by sending the “AT+QPOWD=1” command, using the
PWRKEY or the EMERG_OFF1) 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.
“AT+CFUN” command can set the module to a minimum functionality mode
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 will be reduced.
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GSM/GPRS Module Series
GC65 Hardware Design
NOTE
Use the EMERG_OFF pin only when failing to turn off the module by the command “AT+QPOWD=1” and
the PWRKEY pin. For more details, please refer to Section 3.4.2.4.
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 4.615 ms, 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 GC65 module, the max current consumption could reach to 1.6A during a transmit burst. 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 transmit burst does not exceed 400mV.
Figure 3: Voltage Drop during Transmitting
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 transmitting burst. If the power voltage drops below 3.3V, the module could turn off
automatically. For better power performance, it is recommended to place a 1000uF tantalum capacitor
with low ESR and ceramic capacitor 100nF, 47pF and 27pF near the VBAT pin. The reference circuit is
illustrated in Figure 4.
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GSM/GPRS Module Series
GC65 Hardware Design
The VBAT route should be wide enough to ensure that there is not too much voltage drop during transmit
burst. The width of trace should be no less than 2mm and the principle of the VBAT route is the longer
route, the wider trace.
Figure 4: Reference Circuit for the VBAT Input
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 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 switching power converter is recommended to be used as a power supply.
Figure 5 shows a reference design for +5V input power source. The designed output for the power supply
is 4.16V 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.
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