Quectel Wireless Solutions 201604M26 Users Manual

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

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Quectel Wireless Solutions Co., Ltd.

Office 501, Building 13, No.99, Tianzhou Road, Shanghai, China, 200233

Tel: [phone]

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Copyright © Quectel Wireless Solutions Co., Ltd. 2014. All rights reserved.

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About the Document

History

	Revision			Date		Author			Description
1.0			2014-08-07			Felix YIN			Initial
								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
1.1			2014-11-24			Felix YIN				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

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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

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			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.				.............................................................................................................................	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

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	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

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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

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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

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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

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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.

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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.

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.

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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.

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2.2. Key Features

The following table describes the detailed features of M26 module.

Table 1: Module Key Features

		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
				 Quad-band: GSM850, EGSM900, DCS1800, PCS1900.
		Frequency Bands		 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 multi-slot class 12 (default)
		GPRS Connectivity		 GPRS multi-slot class 1~12 (configurable)
				 GPRS mobile station class B
				 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
		DATA GPRS		 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)
				 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
		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
				Speech codec modes:
		Audio Features		 Half Rate (ETS 06.20)
				 Full Rate (ETS 06.10)
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		 Enhanced Full Rate (ETS 06.50/06.60/06.80)
		 Adaptive Multi-Rate (AMR)
			Echo Suppression
			Noise Reduction
		UART Port:
		 Seven lines on UART port interface
		 Used for AT command, GPRS data
			Multiplexing function
	UART Interfaces	 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

NOTE

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.

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

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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

RF_ANT
	ESD	RF	PAM
VBAT
	PMU		RF Transceiver		26MHz
PWRKEY
				BT	BT_ANT
VDD_EXT	VDD_EXT
				Serial	UART
				Interface
VRTC	RTC
		BB&RF
SIM	SIM			AUDIO	AUDIO
Interface	Interface
				PCM	PCM
NETLIGHT	PWM	MEMORY		ADC	ADC

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].

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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

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3.1. Pin of Module

3.1.1. Pin Assignment

							VRTC		VBAT			VBAT			GND		GND		TXD_DBG			RXD_DBG		GND		GND
							44		43			42			41		40		39			38		37		36
		AGND			1																								35		RF_ANT
		SPK2P			2																								34		GND
		MICP			3																								33		PCM_OUT
		MICN			4										M26														32		PCM_IN
	SPK1P				5																								31		PCM_SYNC
											Top View
	SPK1N				6																								30		PCM_CLK
	PWRKEY				7																								29		TXD_AUX
		AVDD
					8																								28		RXD_AUX
		ADC0			9																								27		GND
	SIM_GND				10																								26		BT_ANT
	SIM_DATA				11																								25		RFTXMON
	SIM_RST				12																								24		VDD_EXT
	SIM_CLK				13																								23		RTS
							14		15			16			17		18		19			20		21		22
						SIM_VDD			RESERVED			NETLIGHT			RXD		TXD		DTR			RI		DCD		CTS
POWER GND					AUDIO				UART						SIM					PCM					ANT RESERVED OTHERS

Figure 2: Pin Assignment

NOTE

Keep all reserved pins open.

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3.1.2. Pin Description

Table 3: IO Parameters Definition

Type	Description
IO	Bidirectional input/output
DI	Digital input
DO	Digital output
PI	Power input
PO	Power output
AI	Analog input
AO	Analog output

Table 4: Pin Description

Power Supply

	PIN Name	PIN No.	I/O	Description	DC Characteristics	Comment
						Make sure that
						supply
				Main power supply of	VImax=4.6V	sufficient
	VBAT	42,43	PI	module:	VImin=3.3V	current in a
				VBAT=3.3V~4.6V	VInorm=4.0V	transmitting
						burst typically
						rises to 1.6A.
					VImax=3.3V
				Power supply for RTC when	VImin=1.5V
				VBAT is not supplied for the	VInorm=2.8V
	VRTC	44	IO	system.	VOmax=3V	If unused, keep
				Charging for backup battery or	VOmin=2V	this pin open.
				golden capacitor when the	VOnorm=2.8V
				VBAT is applied.	IOmax=2mA
					Iin≈10uA
					VOmax=2.9V	1. If unused,
						keep this pin
	VDD_			Supply 2.8V voltage for	VOmin=2.7V
		24	PO			open.
	EXT			external circuit.	VOnorm=2.8V
						2. Recommend
					IOmax=20mA
						to add a
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				2.2~4.7uF
				bypass
				capacitor,
				when using
				this pin for
				power supply.
		27,34
	GND	36,37	Ground
		40,41
	Turn on/off
	PIN Name	PIN No. I/O	Description	DC Characteristics Comment

				Power on/off key. PWRKEY
	PWRKEY	7	DI	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	3,		Positive and negative voice		If unused, keep
			AI			these pins
	MICN	4		input
						open.
	SPK1P	5,	AO	Channel 1 positive and		If unused, keep
	SPK1N	6		negative voice output		these pins
						open.
					Refer to Section 3.8	Support both
	SPK2P	2	AO	Channel 2 voice output		voice and
						ringtone
						output.
				Analog ground. Separate		If unused, keep
	AGND	1		ground connection for
						this pin open.
				external audio circuits.
	Network Status Indicator

	PIN Name	PIN No.	I/O	Description	DC Characteristics	Comment
					VOHmin=	If unused,
					0.85×VDD_EXT
	NETLIGHT	16	DO	Network status indication		keep this pin
					VOLmax=
						open.
					0.15×VDD_EXT
	UART Port
	PIN Name	PIN No.	I/O	Description	DC Characteristics	Comment

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	TXD	18	DO	Transmit data	VILmin=0V
					VILmax=
	RXD	17	DI	Receive data
					0.25×VDD_EXT	If only use
					VIHmin=	TXD, RXD and
	DTR	19	DI	Data terminal ready
					0.75×VDD_EXT	GND to
	RI	20	DO	Ring indication
					VIHmax=	communicate,
					VDD_EXT+0.2	recommended
	DCD	21	DO	Data carrier detection
					VOHmin=	to keep other
	CTS	22	DO	Clear to send	0.85×VDD_EXT	pins open.
					VOLmax=
	RTS	23	DI	Request to send
					0.15×VDD_EXT
	Debug Port
	PIN Name	PIN No.	I/O	Description	DC Characteristics	Comment
	DBG_	39	DO	Transmit data		If unused,
	TXD
					Same as above	keep these
	DBG_
		38	DI	Receive data		pins open.
	RXD
	Auxiliary Port
	PIN Name	PIN No.	I/O	Description	DC Characteristics	Comment
	TXD_	29	DO	Transmit data		If unused,
	AUX
					Same as above	keep these
	RXD_
		28	DI	Receive data		pins open.
	AUX
	SIM Interface
	PIN Name	PIN No.	I/O	Description	DC Characteristics	Comment

					The voltage can be
	SIM_ VDD	14	PO	Power supply for SIM card	selected by software
					automatically. Either
					1.8V or 3.0V.
					VOLmax=
	SIM_ CLK	13	DO	SIM clock	0.15×SIM_VDD
					VOHmin=
					0.85×SIM_VDD
					VILmax=
					0.25×SIM_VDD
					VIHmin=
	SIM_ DATA	11	IO	SIM data	0.75×SIM_VDD

VOLmax=

0.15×SIM_VDD

VOHmin=

0.85×SIM_VDD

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.

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						VOLmax=
		SIM_ RST	12	DO	SIM reset	0.15×SIM_VDD
						VOHmin=
						0.85×SIM_VDD
		SIM_	10		SIM ground
		GND
		ADC
		PIN Name	PIN No.	I/O	Description	DC Characteristics	Comment
					Reference voltage of	VOmax=2.9V	If unused,
		AVDD	8	PO		VOmin=2.7V	keep this pin
					ADC circuit
						VOnorm=2.8V	open.
					General purpose analog to	Voltage range:	If unused,
		ADC0	9	AI			keep this pin
					digital converter.	0V to 2.8V
							open.
		PCM
		PIN Name	PIN No.	I/O	Description	DC Characteristics	Comment
		PCM_ CLK	30	DO	PCM clock	VILmin= 0V
						VILmax=
		PCM_			PCM frame
			31	DO		0.25×VDD_EXT
		SYNC			synchronization
						VIHmin=
		PCM_
			32	DI	PCM data input	0.75×VDD_EXT	If unused,
		IN
						VIHmax=	keep this pin
						VDD_EXT+0.2	open.
		PCM_				VOHmin=
			33	DO	PCM data output	0.85×VDD_EXT
		OUT
						VOLmax=
						0.15×VDD_EXT
		Antenna Interface
		PIN Name	PIN No.	I/O	Description	DC Characteristics	Comment
		RF_	35	IO	GSM antenna pad	Impedance of 50Ω
		ANT
		BT_					If unused,
			26	IO	BT antenna pad	Impedance of 50Ω	keep this pin
		ANT
							open.
		Transmitting Signal Indication
		PIN Name	PIN No.	I/O	Description	DC Characteristics	Comment
					Transmission signal	VOHmin=	If unused,
		RFTXMON	25	DO		0.85×VDD_EXT	keep this pin
					indication
						VOLmax=	open.
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				0.15×VDD_EXT
	Other Interface
	PIN Name	PIN No. I/O	Description	DC Characteristics	Comment
	RESERVED	15			Keep these
					pins open.

3.2. Operating Modes

The table below briefly summarizes the various operating modes in the following chapters.

Table 5: Overview of Operating Modes

	Mode		Function
				After enabling sleep mode by AT+QSCLK=1, the module will
				automatically enter into Sleep Mode if DTR is set to high level
			GSM/GPRS	and there is no interrupt (such as GPIO interrupt or data on
				UART port). In this case, the current consumption of module
			Sleep
				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
			GSM IDLE	network, and the module is ready to send and receive GSM
				data.
				GSM connection is ongoing. In this mode, the power
	Normal Operation		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.
			GPRS	The module is registered to GPRS network, but no GPRS PDP
				context is active. The SGSN knows the Routing Area where the
			STANDBY
				module is located at.
				The PDP context is active, but no data transfer is ongoing. The
			GPRS READY	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.

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Normal shutdown by sending the AT+QPOWD=1 command or using the PWRKEY pin. The power management ASIC disconnects the power supply from POWER DOWN 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

AT+CFUN command can set the module to a minimum functionality mode

Functionality Mode

without removing the power supply. In this case, the RF part of the module will not

(without removing

work or the SIM card will not be accessible, or both RF part and SIM card will be

power supply)

disabled, but the UART port is still accessible. The power consumption in this case is very low.

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.

4.615ms

577us

Burst:1.6A

IBAT

VBAT

Vdrop

Figure 3: Voltage Ripple during Transmitting

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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.

VBAT

+

C1

C2

C3

C4

100uF

100nF

10pF

33pF

0603

0603

GND

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 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.

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MIC29302WU U1

DC_IN

2 IN

C1

C2

1

R1

470uF

100nF

51K

R5

4.7K

MCU_POWER_ON/OFF

R6

47K

							VBAT
		OUT 4
			R2
EN	3 GND	5 ADJ	124K		C3	C4
				R4			D1
			R3	470R	470uF	100nF	5.1V
			56K

Figure 5: Reference Circuit for Power Supply

NOTE

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.

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.

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