Quectel Wireless Solutions 201511M85 User Manual

M85 Hardware Design

GSM/GPRS Module Series

Rev. M85_Hardware_Design_V3.0

Date: 2015-10-22

www.quectel.com

GSM/GPRS Module Series

M85 Hardware Design

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Quectel Wireless Solutions Co., Ltd.

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Copyright © Quectel Wireless Solutions Co., Ltd. 2015. All rights reserved.

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About the Document

History

	Revision			Date		Author			Description
1.0			2012-07-15			Winter CHEN		Initial
1.1			2013-11-04			Felix YIN		Optimized the parameters of VBAT ripple in Table 33
								1.		Updated module key features in Table 1
								2.		Modified pin assignment in Figure 2
								3.		Updated DC characteristics of module’s pins in
										Table 4
								4.		Updated reference circuit for power supply in
3.0			2015-03-13			Stone YU/				Figure 5
						Hollis WANG		5.		Modified over-voltage or under-voltage automatic
										shutdown in Section 3.4.2.3
								6.		Modified RTC backup in Section 3.6
								7.		Modified UART application in Section 3.7.4
								8.		Deleted the data call mode in Section 3.13
								9.		Added antenna requirement in Section 4.5

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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.	Directives and Standards ......................................................................................................			11
		2.2.1.	FCC Statement...............................................................................................................		11
		2.2.2.	FCC Radiation Exposure Statement..............................................................................		12
	2.3.	Key Features		.........................................................................................................................	12
	2.4.	Functional Diagram ...............................................................................................................			14
	2.5.	Evaluation Board ...................................................................................................................			15
3	Application Interface			.........................................................................................................................	16
	3.1.	Pin of Module.........................................................................................................................			17
		3.1.1.	Pin Assignment ..............................................................................................................		17
		3.1.2.	Pin Description ...............................................................................................................		18
	3.2.	Operating Modes ...................................................................................................................			23
	3.3.	Power Supply ........................................................................................................................			24
		3.3.1. Power Features of Module.............................................................................................			24
		3.3.2. Decrease Supply Voltage Drop......................................................................................			24
		3.3.3. Reference Design For Power Supply ............................................................................			25
		3.3.4.	Monitor Power Supply ....................................................................................................		26
	3.4.	Power On and Down Scenarios ............................................................................................			26
		3.4.1.	Power On .......................................................................................................................		26
		3.4.2.	Power Down ...................................................................................................................		28
		3.4.2.1.		Power Down Module Using the PWRKEY Pin ................................................	28
		3.4.2.2.		Power Down Module Using AT Command ......................................................	29
		3.4.2.3.		Over-voltage or Under-voltage Automatic Shutdown......................................	29
		3.4.2.4.		Emergency Shutdown Using EMERG_OFF Pin .............................................	30
		3.4.3.	Restart ............................................................................................................................		31
	3.5.	Power Saving ........................................................................................................................			32
		3.5.1.	Minimum Functionality Mode .........................................................................................		32
		3.5.2.	SLEEP Mode..................................................................................................................		33
		3.5.3. Wake up Module from SLEEP Mode .............................................................................			33
		3.5.4.	Summary of State Transition..........................................................................................		33
	3.6.	RTC Backup ..........................................................................................................................			34

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	3.7.		Serial Interfaces.....................................................................................................................			36
	3.7.1.			UART Port ......................................................................................................................		38
			3.7.1.1.		The Features of UART Port .............................................................................	38
			3.7.1.2.		The Connection of UART Port .........................................................................	39
			3.7.1.3.		Firmware Upgrade ...........................................................................................	40
	3.7.2.			Debug Port .....................................................................................................................		41
	3.7.3.			Auxiliary UART Port .......................................................................................................		42
	3.7.4.			UART Application ...........................................................................................................		42
	3.8.		Audio Interfaces.....................................................................................................................			44
		3.8.1. Decrease TDD Noise and Other Noise..........................................................................				45
	3.8.2.			Microphone Interfaces Design .......................................................................................		46
		3.8.3. Receiver and Speaker Interface Design ........................................................................				46
	3.8.4.			Earphone Interface Design ............................................................................................		48
		3.8.5. Loud Speaker Interface Design......................................................................................				49
	3.8.6.			Audio Characteristics .....................................................................................................		49
	3.9.		SIM Card Interfaces ..............................................................................................................			50
	3.10.		SD Card Interface..................................................................................................................			53
	3.11.		PCM Interface........................................................................................................................			55
	3.11.1.			Configuration ..................................................................................................................		56
	3.11.2.			Timing	.............................................................................................................................	56
	3.11.3.			Reference Design ..........................................................................................................		58
	3.11.4.			AT Command .................................................................................................................		58
	3.12.		ADC .......................................................................................................................................			59
	3.13.		Behaviors Of ..............................................................................................................The RI			60
	3.14.		Network Status ......................................................................................................Indication			62
	3.15.		Operating Status ...................................................................................................Indication			62
4	Antenna Interface...............................................................................................................................					64
	4.1.		Reference Design..................................................................................................................			64
	4.2.		RF Output Power...................................................................................................................			65
	4.3.		RF Receiving ........................................................................................................Sensitivity			65
	4.4.		Operating Frequencies..........................................................................................................			66
	4.5.		Antenna Requirement ...........................................................................................................			66
	4.6.		RF Cable Soldering ...............................................................................................................			67
5 Electrical, Reliability ............................................................................and Radio Characteristics						68
	5.1.		Absolute Maximum ...................................................................................................Ratings			68
	5.2.		Operating Temperature .........................................................................................................			69
	5.3.		Power Supply ...........................................................................................................Ratings			69
	5.4.		Current Consumption ............................................................................................................			70
	5.5.		Electro-static ........................................................................................................Discharge			72
6	Mechanical Dimensions ....................................................................................................................					74
	6.1.		Mechanical .......................................................................................Dimensions of Module			74
	6.2.		Recommended .......................................................................................................Footprint			76
	6.3.		Top View of .........................................................................................................the Module			77
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	6.4.	Bottom View of the Module ...................................................................................................		77
7	Storage and Manufacturing ..............................................................................................................			78
	7.1.	Storage ..................................................................................................................................		78
	7.2.	Soldering ...............................................................................................................................		79
	7.3.	Packaging..............................................................................................................................		80
8	Appendix A Reference.......................................................................................................................			82
9	Appendix B GPRS Coding Scheme .................................................................................................			87
10	Appendix C GPRS Multi-slot Class..................................................................................................			89

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Table Index
TABLE 1: MODULE KEY FEATURES ...............................................................................................................	12
TABLE 2: CODING SCHEMES AND MAXIMUM NET DATA RATES OVER AIR INTERFACE ........................	14
TABLE 3: PIN DESCRIPTION ...........................................................................................................................	18
TABLE 4: OVERVIEW OF OPERATING MODES .............................................................................................	23
TABLE 5: SUMMARY OF STATE TRANSITION ...............................................................................................	33
TABLE 6: LOGIC LEVELS OF THE UART INTERFACE ..................................................................................	37
TABLE 7: PIN DEFINITION OF THE UART INTERFACES ..............................................................................	37
TABLE 8: PIN DEFINITION OF AUDIO INTERFACE .......................................................................................	44
TABLE 9: AOUT3 OUTPUT CHARACTERISTICS............................................................................................	45
TABLE 10: TYPICAL ELECTRET MICROPHONE CHARACTERISTICS.........................................................	49
TABLE 11: TYPICAL SPEAKER CHARACTERISTICS.....................................................................................	49
TABLE 12: PIN DEFINITION OF THE SIM INTERFACE ..................................................................................	50
TABLE 13: PIN DEFINITION OF THE SD CARD INTERFACE ........................................................................	54
TABLE 14: PIN DEFINITION OF THE SD CARD INTERFACE ........................................................................	54
TABLE 15: PIN DEFINITION OF PCM INTERFACE.........................................................................................	55
TABLE 16: CONFIGURATION...........................................................................................................................	56
TABLE 17: QPCMON COMMAND DESCRIPTION ..........................................................................................	59
TABLE 18: QPCMVOL COMMAND DESCRIPTION.........................................................................................	59
TABLE 19: PIN DEFINITION OF THE ADC ......................................................................................................	60
TABLE 20: CHARACTERISTICS OF THE ADC................................................................................................	60
TABLE 21: BEHAVIORS OF THE RI .................................................................................................................	60
TABLE 22: WORKING STATE OF THE NETLIGHT..........................................................................................	62
TABLE 23: PIN DEFINITION OF THE STATUS ................................................................................................	63
TABLE 24: PIN DEFINITION OF THE RF_ANT ................................................................................................	64
TABLE 25: THE MODULE CONDUCTED RF OUTPUT POWER ....................................................................	65
TABLE 26: THE MODULE CONDUCTED RF RECEIVING SENSITIVITY .......................................................	65
TABLE 27: THE MODULE OPERATING FREQUENCIES................................................................................	66
TABLE 28: ANTENNA CABLE REQUIREMENTS.............................................................................................	66
TABLE 29: ANTENNA REQUIREMENTS..........................................................................................................	66
TABLE 30: ABSOLUTE MAXIMUM RATINGS ..................................................................................................	68
TABLE 31: OPERATING TEMPERATURE........................................................................................................	69
TABLE 32: THE MODULE POWER SUPPLY RATINGS ..................................................................................	69
TABLE 33: THE MODULE CURRENT CONSUMPTION ..................................................................................	70
TABLE 34: THE ESD ENDURANCE (TEMPERATURE: 25ºC, HUMIDITY: 45%) ............................................	73
TABLE 35: REEL PACKING ..............................................................................................................................	81
TABLE 36: RELATED DOCUMENTS ................................................................................................................	82
TABLE 37: TERMS AND ABBREVIATIONS ......................................................................................................	83
TABLE 38: DESCRIPTION OF DIFFERENT CODING SCHEMES ..................................................................	87
TABLE 39: GPRS MULTI-SLOT CLASSES ......................................................................................................	89

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Figure Index
FIGURE 1: MODULE FUNCTIONAL DIAGRAM...............................................................................................		15
FIGURE 2: PIN ASSIGNMENT .........................................................................................................................		17
FIGURE 3: VOLTAGE RIPPLE DURING TRANSMITTING ..............................................................................		24
FIGURE 4: REFERENCE CIRCUIT FOR THE VBAT INPUT ...........................................................................		25
FIGURE 5: REFERENCE CIRCUIT FOR POWER SUPPLY ............................................................................		25
FIGURE 6: TURN ON THE MODULE WITH AN OPEN-COLLECTOR DRIVER..............................................		26
FIGURE 7: TURN ON THE MODULE WITH A BUTTON ..................................................................................		27
FIGURE 8: TURN-ON TIMING ..........................................................................................................................		27
FIGURE 9: TURN-OFF TIMING ........................................................................................................................		28
FIGURE 10: AN OPEN-COLLECTOR DRIVER FOR EMERG_OFF ................................................................		30
FIGURE 11: REFERENCE CIRCUIT FOR EMERG_OFF BY USING BUTTON ..............................................		31
FIGURE 12: TIMING OF RESTARTING SYSTEM............................................................................................		31
FIGURE 13: TIMING OF RESTARTING SYSTEM AFTER EMERGENCY SHUTDOWN ................................		32
FIGURE 14: VRTC IS SUPPLIED BY A NON-CHARGEABLE BATTERY........................................................		35
FIGURE 15: VRTC IS SUPPLIED BY A RECHARGEABLE BATTERY ............................................................		35
FIGURE 16: VRTC IS SUPPLIED BY A CAPACITOR ......................................................................................		36
FIGURE 17: REFERENCE DESIGN FOR FULL-FUNCTION UART................................................................		39
FIGURE 18: REFERENCE DESIGN FOR UART PORT...................................................................................		40
FIGURE 19: REFERENCE DESIGN FOR UART PORT WITH HARDWARE FLOW CONTROL ....................		40
FIGURE 20: REFERENCE DESIGN FOR FIRMWARE UPGRADE.................................................................		41
FIGURE 21: REFERENCE DESIGN FOR DEBUG PORT ...............................................................................		41
FIGURE 22: REFERENCE DESIGN FOR AUXILIARY UART PORT ...............................................................		42
FIGURE 23: LEVEL MATCH DESIGN FOR 3.3V SYSTEM..............................................................................		42
FIGURE 24: SKETCH MAP FOR RS-232 INTERFACE MATCH......................................................................		43
FIGURE 25: REFERENCE DESIGN FOR AIN1&AIN2 .....................................................................................		46
FIGURE 26: HANDSET INTERFACE DESIGN FOR AOUT1 ...........................................................................		46
FIGURE 27: SPEAKER INTERFACE DESIGN WITH AN AMPLIFIER FOR AOUT1 .......................................		47
FIGURE 28: HANDSET INTERFACE DESIGN FOR AOUT2 ...........................................................................		47
FIGURE 29: SPEAKER INTERFACE DESIGN WITH AN AMPLIFIER FOR AOUT2 .......................................		48
FIGURE 30: EARPHONE INTERFACE DESIGN..............................................................................................		48
FIGURE 31: LOUD SPEAKER INTERFACE DESIGN......................................................................................		49
FIGURE 32: REFERENCE CIRCUIT FOR SIM1 INTERFACE WITH 8-PIN SIM CARD HOLDER .................		51
FIGURE 33: REFERENCE CIRCUIT FOR SIM1 INTERFACE WITH THE 6-PIN SIM CARD HOLDER .........		52
FIGURE 34: REFERENCE CIRCUIT FOR SIM2 INTERFACE WITH THE 6-PIN SIM CARD HOLDER .........		52
FIGURE 35: REFERENCE CIRCUIT FOR SD CARD ......................................................................................		54
FIGURE 36: LONG SYNCHRONIZATION & SIGN EXTENSION DIAGRAM ...................................................		57
FIGURE 37: LONG SYNCHRONIZATION & ZERO PADDING DIAGRAM.......................................................		57
FIGURE 38: SHORT SYNCHRONIZATION & SIGN EXTENSION DIAGRAM.................................................		57
FIGURE 39: SHORT SYNCHRONIZATION & ZERO PADDING DIAGRAM ....................................................		58
FIGURE 40: REFERENCE DESIGN FOR PCM ...............................................................................................		58
FIGURE 41: RI BEHAVIOR OF VOICE CALLING AS A RECEIVER ................................................................		61
FIGURE 42: RI BEHAVIOR AS A CALLER .......................................................................................................		61
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FIGURE 43: RI BEHAVIOR OF URC OR SMS RECEIVED .............................................................................	61
FIGURE 44: REFERENCE DESIGN FOR NETLIGHT .....................................................................................	62
FIGURE 45: REFERENCE DESIGN FOR STATUS..........................................................................................	63
FIGURE 46: REFERENCE DESIGN FOR RF ..................................................................................................	64
FIGURE 47: RF SOLDERING SAMPLE ...........................................................................................................	67
FIGURE 48: M85 MODULE TOP AND SIDE DIMENSIONS (UNIT: MM) .........................................................	74
FIGURE 49: M85 MODULE BOTTOM DIMENSIONS (UNIT: MM)...................................................................	75
FIGURE 50: THE PAD DIMENSIONS (UNIT: MM) ...........................................................................................	75
FIGURE 51: RECOMMENDED FOOTPRINT (UNIT: MM)................................................................................	76
FIGURE 52: TOP VIEW OF THE MODULE ......................................................................................................	77
FIGURE 53: BOTTOM VIEW OF THE MODULE..............................................................................................	77
FIGURE 54: RAMP-SOAK-SPIKE REFLOW PROFILE....................................................................................	79
FIGURE 55: TAPE AND REEL INFORMATION ................................................................................................	81
FIGURE 56: RADIO BLOCK STRUCTURE OF CS-1, CS-2 AND CS-3...........................................................	87
FIGURE 57: RADIO BLOCK STRUCTURE OF CS-4.......................................................................................	88

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1 Introduction

This document defines the M85 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 notes and user guide, you can use M85 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 M85 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 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.

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

M85 is a Quad-band GSM/GPRS engine that works at frequencies of GSM850MHz, EGSM900MHz, DCS1800MHz and PCS1900MHz. The M85 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 24.5mm × 25.3mm × 2.6mm, 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.

M85 is an SMD type module with LCC package, which can be easily embedded into applications. It provides abundant hardware interfaces like PCM and SD Card Interface.

Designed with power saving technique, the current consumption of M85 is as low as 1.3 mA in SLEEP mode when DRX is 5.

M85 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.

The module fully complies with the RoHS directive of the European Union.

2.2. Directives and Standards

The M85 module is designed to comply with the FCC statements. FCC ID: XMR201511M85

The Host system using M85 should have label ―contains FCC ID: XMR201511M85‖.

2.2.1. FCC Statement

Changes or modifications not expressly approved by the party responsible for compliance could void the

user’s authority to operate the equipment.

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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 M85, must include RF exposure warning statement to advice user should keep minimum 20cm from the radio antenna of M85 module depending on the Mobile status. Note: If a portable device (such as PDA) uses M85 module, the device needs to do permissive change and SAR testing.

The following list indicates the performance of antenna gain in certificate testing.

	Part	Frequency Range (MHz)	Peak Gain	Average	VS	Impedanc
	Number		(XZ-V)	Gain(XZ-V)	WR	e
		GSM850:824 894MHz
	3R007	EGSM900:880 960MHz	1 dBi typ.	1 dBi typ.	2 max	50Ω
		DCS1800:1710 1880MHz
		PCS1900: 1850 1990MHz

2.3. Key Features

The following table describes the detailed features of M85 module.

Table 1: Module Key Features

		Feature		Implementation
		Power Supply		Single supply voltage: 3.3V~4.6V
				Typical supply voltage: 4.0V
		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
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				 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
				 Support the protocols PAP (Password Authentication Protocol)
	DATA GPRS				usually used for PPP connections
					Internet service protocols:
					TCP/UDP/FTP/PPP/HTTP/NTP/MMS/SMTP/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
	SMS			 Text and PDU mode
				 SMS storage: SIM card
	SIM Interfaces			Support SIM card: 1.8V, 3V
				Speech codec modes:
				 Half Rate (ETS 06.20)
				 Full Rate (ETS 06.10)
				 Enhanced Full Rate (ETS 06.50/06.60/06.80)
	Audio Features				Adaptive Multi-Rate (AMR)
					Echo Suppression
					Noise Reduction
				 Embedded one amplifier of class AB with maximum driving power up
					to 870mW
				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
				 Use for software debugging and log output
				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

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	Physical Characteristics			Size: 25.3±0.15 × 24.5±0.15 × 2.6±0.2mm
				Weight: Approx. 3.3g
	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

2.4. Functional Diagram

The following figure shows a block diagram of M85 and illustrates the major functional parts.

Radio frequency part

Serial Flash

Power management

The Peripheral interface

—Power supply

—Turn-on/off interface

—UART interfaces

—Audio interfaces

—SIM interfaces

—SD interface

—PCM interface

—ADC interface

—RTC interface

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—RF interface

RF_ANT
	ESD	RF	PAM
VBAT
PWRKEY	PMU	RF Transceiver			26MHz
EMERG_OFF	Reset
VRTC	RTC			ADC	ADC
SIM Interfaces	SIM	BB&RF		PCM	PCM
	Interface			Interface
GPIO&				SD	SD
Status&	GPIO&PWM
				Interface
Netlight
UART	Serial Interface	MEMORY		Audio	Audio
		Serial Flash

Figure 1: Module Functional Diagram

2.5. Evaluation Board

In order to help customer to develop applications with M85, 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 [12].

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3 Application Interface

The module adopts LCC package and has 83 pins. The following chapters provide detailed descriptions about these pins below.

Power supply

Power on/down

Power saving

RTC

Serial interfaces

Audio interfaces

SIM interfaces

SD interface

PCM interface

ADC

RI

NETLIGHT

Status

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3.1. Pin of Module

3.1.1. Pin Assignment

SIM2 RST

SIM2 DATA

SIM2 CLK

SIM2 VDD

VBAT

VBAT

VBAT

VBAT

GND

GND

GND

RF ANT

GND

GND

VDD EXT

VRTC

RESERVED

SIM1 PRESENCE

74

73

72

71

70

69

68

67

66 65

64

63

62

61

60

59

58

57

RESERVED 1

ADC0 2

RESERVED 3

Top view

NETLIGHT 4

SPK2P 5

AGND 6

GND

MIC2P 7

RESERVED

MIC2N 8

RESERVED 75

82

81 GND

MIC1P 9

MIC1N 10

RESERVED 76

83

80 GND

SPK1N 11

RESERVED 77

78

79 GND

SPK1P 12

LOUDSPKN 13

RESERVED

LOUDSPKP 14

PWRKEY 15

STATUS 16

EMERG_OFF 17

PCM_IN 18

PCM_CLK 19

20

21

22

23

24

25

26

27 28

29 30

31

32

33

34

35

36

37

PCM OUT

PCM SYNC

RESERVED

RESERVED

RESERVED

RESERVED

RESERVED

RESERVED

RESERVED

RESERVED

RESERVED

RESERVED

RESERVED

RESERVED

SD CMD

SD CLK

SD DATA0

GND

VBAT

SIM2

GND

RF

UART

Audio

ADC

Power

Other

SIM1

RESERVED

SD

PCM

Figure 2: Pin Assignment

NOTE

56 SIM1_VDD

55 SIM1_CLK

54 SIM1_DATA

53 SIM1_RST

52 SIM_GND

51 RTS

50 RXD

49 TXD

48 CTS

47 DTR

46 RI

45 DCD

44 RESERVED

43 DBG_RXD

42 DBG_TXD

41 RXD_AUX

40 TXD_AUX

39 RESERVED

38 RESERVED

Keep all reserved pins open.

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3.1.2. Pin Description

Table 3: Pin Description

Power Supply

		PIN NAME	PIN NO.	I/O	DESCRIPTION	DC	COMMENT
						CHARACTERISTICS
							Make sure that
					Main power supply of	Vmax=4.6V	supply sufficient
			67, 68, 69,				current in a
		VBAT		I	module:	Vmin=3.3V
			70				transmitting burst
					VBAT=3.3V~4.6V	Vnorm=4.0V
							typically rises to
							1.6A.
						VImax=3.3V
					Power supply for RTC.	VImin=1.5V
						VInorm=2.8V
					Charging for backup
						VOmax=3V	If unused, keep
		VRTC	59	I/O	battery or golden
						VOmin=2V	this pin open.
					capacitor when the
						VOnorm=2.8V
					VBAT is applied.
						Iout(max)=2mA
						Iin≈10uA
							1. If unused, keep
							this pin open.
						Vmax=2.9V	2. Recommend to
		VDD_EXT	60	O	Supply 2.8V voltage for	Vmin=2.7V	add a 2.2~4.7uF
					external circuit.	Vnorm=2.8V	bypass capacitor,
						Imax=20mA	when using this
							pin for power
							supply.
			37, 61, 62,
		GND	64~66,		Ground
			79~82,
		Turn on/off
		PIN NAME	PIN NO.	I/O	DESCRIPTION	DC	COMMENT
						CHARACTERISTICS
					Power on/off key.	VILmax=
						0.1×VBAT
					PWRKEY should be pulled
		PWRKEY	15	I		VIHmin=
					down for a moment to turn
						0.6×VBAT
					on or turn off the system.
						VIHmax=3.1V
		Emergency Shutdown
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		PIN NAME		PIN NO.		I/O	DESCRIPTION	DC	COMMENT
								CHARACTERISTICS
							Emergency off. Pulled		Open
							down for at least 40ms,		drain/collector
							which will turn off the	VILmax=0.45V	driver required in
		EMERG_					module in case of		cellular device
				17		I		VIHmin=1.35V
		OFF					emergency. Use it only		application.
								Vopenmax=1.8V
							when shutdown via		If unused, keep
							PWRKEY or AT command		this pin open.
							cannot be achieved.
		Module Indicator
		PIN NAME		PIN NO.		I/O	DESCRIPTION	DC	COMMENT
								CHARACTERISTICS
							Indicate module’s
							operating status. Output	VOHmin=
		STATUS		16		O	high level when module	0.85×VDD_EXT	If unused, keep
							turns on, while output low	VOLmax=	this pin open.
							level when module turns	0.15×VDD_EXT
							off.
		Audio Interface
		PIN NAME		PIN NO.		I/O	DESCRIPTION	DC	COMMENT
								CHARACTERISTICS
		MIC1P		9, 10		I	Channel 1 positive and
		MIC1N					negative voice input		If unused, keep
									these pins open.
		MIC2P		7, 8		I	Channel 2 positive and
		MIC2N					negative voice input
		SPK1P		12, 11		O	Channel 1 positive and		1. If unused, keep
		SPK1N					negative voice output		these pins open.
									2. Support both
		SPK2P		5		O	Channel 2 voice output		voice and
									ringtone output.
							Analog ground. Separate		If unused, keep
		AGND		6			ground connection for	Refer to Section 3.8
									this pin open.
							external audio circuits.
									1. If unused, keep
									these pins open.
									2. Integrate a
		LOUDSPKN		13, 14		O	Channel 3 positive and		ClassAB
		LOUDSPKP					negative voice output		amplifier
									internally.
									3. Support both
									voice and
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										ringtone output.
		Network Status Indicator
		PIN NAME		PIN NO.		I/O	DESCRIPTION		DC	COMMENT
									CHARACTERISTICS
									VOHmin=
		NETLIGHT		4		O	Network status		0.85×VDD_EXT	If unused, keep
							indication		VOLmax=	this pin open.
									0.15×VDD_EXT
		UART Port
		PIN NAME		PIN NO.		I/O	DESCRIPTION		DC	COMMENT
									CHARACTERISTICS
		DTR		47		I	Data terminal ready		VILmin=0V
									VILmax=	If only use TXD,
		RXD		50		I	Receive data
									0.25×VDD_EXT	RXD and GND to
		TXD		49		O	Transmit data		VIHmin=	communicate,
									0.75×VDD_EXT	recommended
		RTS		51		I	Request to send		VIHmax=	connecting RTS
									VDD_EXT+0.2	to GND via 0R
		CTS		48		O	Clear to send
									VOHmin=	resistor and
									0.85×VDD_EXT	keeping other
		RI		46		O	Ring indication
									VOLmax=	pins open.
		DCD		45		O	Data carrier detection		0.15×VDD_EXT
		Debug Port
		PIN NAME		PIN NO.		I/O	DESCRIPTION		DC	COMMENT
									CHARACTERISTICS
		DBG_TXD		42		O	Transmit data			If unused, keep
									Same as above
										these pins open.
		DBG_RXD		43		I	Receive data
		Auxiliary Port
		PIN NAME		PIN NO.		I/O	DESCRIPTION		DC	COMMENT
									CHARACTERISTICS
		TXD_AUX		40		O	Transmit data			If unused, keep
									Same as above
										these pins open.
		RXD_AUX		41		I	Receive data
		SIM Interface
		PIN NAME		PIN NO.		I/O	DESCRIPTION		DC	COMMENT
									CHARACTERISTICS

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		SIM1_VDD		56				The voltage can be
							Power supply for SIM	selected by software
						O
							card	automatically. Either
		SIM2_VDD		71
								1.8V or 3V.
		SIM1_CLK		55				VOLmax=	All signals of SIM
								0.15×SIM_VDD
						O	SIM clock		interface should be
								VOHmin=
									protected against
		SIM2_CLK		72				0.85×SIM_VDD
									ESD with a TVS
								VILmax=	diode array.
								0.25×SIM_VDD	Maximum trace
		SIM1_ DATA		54				VIHmin=
									length is 200mm
								0.75×SIM_VDD
						I/O	SIM data		from the module
								VOLmax=
								0.15×SIM_VDD	pad to SIM card
		SIM2_DATA		73				VOHmin=	holder.
								0.85×SIM_VDD
		SIM1_RST		53				VOLmax=
						O	SIM reset	0.15×SIM_VDD
								VOHmin=
		SIM2_RST		74
								0.85×SIM_VDD
								VILmin=0V
								VILmax=
		SIM1_						0.25×VDD_EXT	If unused, keep
				57		I	SIM card detection	VIHmin=
		PRESENCE							these pins open.
								0.75×VDD_EXT
								VIHmax=
								VDD_EXT+0.2
		SIM_GND		52			SIM ground
		ADC
		PIN NAME		PIN NO.		I/O	DESCRIPTION	DC	COMMENT
								CHARACTERISTICS
							General purpose	Voltage range:	If unused, keep
		ADC0		2		I	analog to digital
								0V to 2.8V	this pin open.
							converter.
		PCM
		PIN NAME		PIN NO.		I/O	DESCRIPTION	DC	COMMENT
								CHARACTERISTICS
		PCM_CLK		19		O	PCM clock
								VILmin= 0V	If unused, keep
		PCM_IN		18		I	PCM data input	VILmax=	these pins open.

0.25×VDD_EXT

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					VIHmin=
	PCM_OUT	20	O	PCM data output	0.75×VDD_EXT
					VIHmax=
					VDD_EXT+0.2	If unused, keep
				PCM frame	VOHmin=	these pins open.
	PCM_SYNC	21	O		0.85×VDD_EXT
				synchronization
					VOLmax=
					0.15×VDD_EXT
	SD Card
	PIN NAME	PIN NO.	I/O	DESCRIPTION	DC	COMMENT
					CHARACTERISTICS
					VILmin=0V
	SD_CMD	34	O	SD command	VILmax=
					0.25×VDD_EXT
					VIHmin=
					0.75×VDD_EXT	If unused, keep
	SD_CLK	35	O	SD clock	VIHmax=
						these pins open.
					VDD_EXT+0.2
					VOHmin=
					0.85×VDD_EXT
	SD_DATA0	36	I/O	SD data	VOLmax=
					0.15×VDD_EXT
	Antenna Interface
	PIN NAME	PIN NO.	I/O	DESCRIPTION	DC	COMMENT
					CHARACTERISTICS
	RF_ANT	63	I/O	RF antenna pad	Impedance of 50Ω
	Other Interface
	PIN NAME	PIN NO.	I/O	DESCRIPTION	DC	COMMENT
					CHARACTERISTICS
		1, 3,
		22~33,
	RESERVD	38, 39,				Keep these pins
		44, 58,				open.
		75~78,
		83

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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
			After enabling sleep mode by AT+QSCLK=1, the module will
			automatically go into Sleep Mode if DTR is set to high level and
		GSM/GPRS	there is no interrupt (such as GPIO interrupt or data on UART
		Sleep	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 connection is ongoing. In this mode, the power
		GSM TALK	consumption is decided by the configuration of Power Control
Normal			Level (PCL), dynamic DTX control and the working RF band.
Operation		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 consumption
		GPRS DATA	is decided by the PCL, working RF band and GPRS multi-slot
			configuration.
		Normal shutdown by sending the AT+QPOWD=1 command or using the PWRKEY
		or the EMERG_OFF1) pin. The power management ASIC disconnects the power
POWER DOWN		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		AT+CFUN command can set the module to a minimum functionality mode without
Functionality		removing the power supply. In this case, the RF part of the module will not work or
Mode (without		the SIM card will not be accessible, or both RF part and SIM card will be disabled,
removing power		but the UART port is still accessible. The power consumption in this case is very
supply)		low.

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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 the 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 4.615ms, 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 M85 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.

4.615ms

577us

Burst:1.6A

IBAT

VBAT

Vdrop

Figure 3: Voltage Ripple 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 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 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.

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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.

Figure 5 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.

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

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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.

PWRKEY

4.7K

Turn on pulse

47K

Figure 6: Turn on the Module with an Open-collector Driver

NOTES

1.M85 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

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