Quectel M66 Supplement

M66 Hardware Design
GSM/GPRS Module Series
Rev. M66_Hardware_Design_V1.1
Date: 2014-11-24
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About the Document
History
Revision
Date
Author
Description
1.0
2014-08-07
Felix YIN
Initial
1.1
2014-11-24
Felix YIN
1. Modified output power of Bluetooth
2. Modified the timing of the RFTXMON signal
3. Updated Figure 5: Reference circuit for power
supply
4. Modified description of RTC and SIM card
interface
5. Modified description of UART Application
6. Deleted the over-voltage automatic shutdown
function
7. Modified the antenna gain in the Table 24
8. Modified the current consumption information in
Section 5.3 & 5.4
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Contents
About the Document...................................................................................................................................2
Contents.......................................................................................................................................................3
Table Index...................................................................................................................................................6
Figure Index.................................................................................................................................................7
1Introduction..........................................................................................................................................9
1.1. Safety Information....................................................................................................................10
2Product Concept................................................................................................................................11
2.1. General Description................................................................................................................. 11
2.2. Key Features ...........................................................................................................................12
2.3. Functional Diagram .................................................................................................................14
2.4. Evaluation Board .....................................................................................................................14
3Application 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
3.7.1.3. Firmware Upgrade.............................................................................................36
3.7.2. Debug Port .....................................................................................................................37
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3.7.3. Auxiliary UART Port .......................................................................................................38
3.7.4. UART Application ...........................................................................................................38
3.8. Audio Interfaces.......................................................................................................................40
3.8.1. Decrease TDD Noise and other Noise ..........................................................................41
3.8.2. Microphone Interfaces Design .......................................................................................41
3.8.3. Receiver and Speaker Interface Design ........................................................................42
3.8.4. Earphone Interface Design ............................................................................................44
3.8.5. Audio Characteristics .....................................................................................................44
3.9. PCM Interface..........................................................................................................................45
3.9.1. Configuration..................................................................................................................45
3.9.2. Timing.............................................................................................................................46
3.9.3. Reference Design ..........................................................................................................48
3.9.4. AT Command .................................................................................................................48
3.10. SIM Card Interface...................................................................................................................49
3.11. ADC .........................................................................................................................................51
3.12. Behaviors of The RI.................................................................................................................51
3.13. Network Status Indication........................................................................................................53
3.14. RF Transmitting Signal Indication............................................................................................54
4Antenna 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
5Electrical, 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
6Mechanical 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
7Storage and Manufacturing ..............................................................................................................70
7.1. Storage.....................................................................................................................................70
7.2. Soldering..................................................................................................................................71
7.3. Packaging................................................................................................................................71
7.3.1. Tape and Reel Packaging..............................................................................................72
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8Appendix A Reference.......................................................................................................................73
9Appendix B GPRS Coding Scheme .................................................................................................78
10 Appendix C GPRS Multi-slot Class..................................................................................................80
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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: M66 MODULE TOP AND SIDE DIMENSIONS (UNIT: MM)......................................................... 66
FIGURE 44: M66 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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1Introduction
This document defines the M66 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 M66 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 M66 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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2Product Concept
2.1. General Description
M66 is a Quad-band GSM/GPRS engine that works at frequencies of GSM850MHz, EGSM900MHz,
DCS1800MHz and PCS1900MHz. The M66 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.
M66 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 M66 is as low as 1.3 mA in SLEEP
mode when DRX is 5.
M66 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.
M66 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 M66 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
Frequency Bands
Quad-band: GSM850, EGSM900, DCS1800, PCS1900.
The module can search these frequency bands automatically
The frequency bands can be set by AT command
Compliant to GSM Phase 2/2+
GSM Class
Small MS
Transmitting Power
Class 4 (2W) at GSM850 and EGSM900
Class 1 (1W) at DCS1800 and PCS1900
GPRS Connectivity
GPRS multi-slot class 12 (default)
GPRS multi-slot class 1~12 (configurable)
GPRS mobile station class B
DATA GPRS
GPRS data downlink transfer: max. 85.6kbps
GPRS data uplink transfer: max. 85.6kbps
Coding scheme: CS-1, CS-2, CS-3 and CS-4
Support the protocols PAP (Password Authentication Protocol)
usually used for PPP connections
Internet service protocols TCP/UDP, FTP, PPP, HTTP, NTP, PING
Support Packet Broadcast Control Channel (PBCCH)
Support Unstructured Supplementary Service Data (USSD)
Temperature Range
Normal operation: -35°C ~ +80°C
Restricted operation: -40°C ~ -35°C and +80°C ~ +85°C 1)
Storage temperature: -45°C ~ +90°C
Bluetooth
Support Bluetooth specification 3.0
Output Power: Class 1 (Typical 7.5dBm)
SMS
Text and PDU mode
SMS storage: SIM card
SIM Interface
Support SIM card: 1.8V, 3.0V
Audio Features
Speech codec modes:
Half Rate (ETS 06.20)
Full Rate (ETS 06.10)
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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
Enhanced Full Rate (ETS 06.50/06.60/06.80)
Adaptive Multi-Rate (AMR)
Echo Suppression
Noise Reduction
UART Interfaces
UART Port:
Seven lines on UART port interface
Used for AT command, GPRS data
Multiplexing function
Support autobauding from 4800bps to 115200bps
Debug Port:
Two lines on debug port interface DBG_TXD and DBG_RXD
Debug Port only used for firmware debugging
Auxiliary Port:
Used for AT command
Phonebook Management
Support phonebook types: SM, ME, ON, MC, RC, DC, LD, LA
SIM Application Toolkit
Support SAT class 3, GSM 11.14 Release 99
Real Time Clock
Supported
Physical Characteristics
Size: 15.8±0.15 ×17.7±0.15 ×2.3±0.2mm
Weight: Approx. 1.3g
Firmware Upgrade
Firmware upgrade via UART Port
Antenna Interface
Connected to antenna pad with 50 Ohm impedance control
Coding Scheme
1 Timeslot
2 Timeslot
4 Timeslot
CS-1
9.05kbps
18.1kbps
36.2kbps
CS-2
13.4kbps
26.8kbps
53.6kbps
CS-3
15.6kbps
31.2kbps
62.4kbps
CS-4
21.4kbps
42.8kbps
85.6kbps
NOTE
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2.3. Functional Diagram
The following figure shows a block diagram of M66 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
BB&RF
RF PAM
26MHzRF Transceiver
RTC
AUDIO
Serial
Interface
SIM
Interface
RF_ANT
VBAT
PWRKEY
VRTC
NETLIGHT
UART
SIM
Interface
ESD
PMU
MEMORY
BT_ANT
PWM
AUDIO
PCM PCM
ADC ADC
BT
VDD_EXT
VDD_EXT
Figure 1: Module Functional Diagram
2.4. Evaluation Board
In order to help you to develop applications with M66, 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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3Application 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
AGND
SPK2P
MICP
MICN
SPK1P
SPK1N
PWRKEY
SIM_RST
SIM_CLK
CTS
VRTC
VBAT
GND
GND
DBG_TXD
DBG_RXD
GND
GND
RF_ANT
14
M66
Top View
15 16 17 18 19 20
21 22 36
37 38 39 40 41 42 43 44
1
2
3
4
5
6
7
8
9
10
11
12
13 23
24
25
26
27
28
29
30
31
32
33
34
35
AVDD
ADC0
SIM_GND
SIM_DATA
GND
PCM_OUT
PCM_IN
PCM_SYNC
PCM_CLK
TXD_AUX
RXD_AUX
GND
BT_ANT
RFTXMON
VDD_EXT
RTS
DCD
RI
DTR TXD
RXD
NETLIGHT
RESERVED
SIM_VDD
VBAT
POWER GND AUDIO UART SIM PCM ANT OTHERS
RESERVED
Figure 2: Pin Assignment
Keep all reserved pins open.
NOTE
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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
VBAT
42,43
PI
Main power supply of
module:
VBAT=3.3V~4.6V
VImax=4.6V
VImin=3.3V
VInorm=4.0V
Make sure that
supply
sufficient
current in a
transmitting
burst typically
rises to 1.6A.
VRTC
44
IO
Power supply for RTC when
VBAT is not supplied for the
system.
Charging for backup battery or
golden capacitor when the
VBAT is applied.
VImax=3.3V
VImin=1.5V
VInorm=2.8V
VOmax=3V
VOmin=2V
VOnorm=2.8V
IOmax=2mA
Iin≈10uA
If unused, keep
this pin open.
VDD_
EXT
24
PO
Supply 2.8V voltage for
external circuit.
VOmax=2.9V
VOmin=2.7V
VOnorm=2.8V
IOmax=20mA
1. If unused,
keep this pin
open.
2. Recommend
to add a
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2.2~4.7uF
bypass
capacitor,
when using
this pin for
power supply.
GND
27,34
36,37
40,41
Ground
Turn on/off
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
PWRKEY
7
DI
Power on/off key. PWRKEY
should be pulled down for a
moment to turn on or turn off
the system.
VILmax=
0.1×VBAT
VIHmin=
0.6×VBAT
VIHmax=3.1V
Audio Interface
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
MICP
MICN
3,
4
AI
Positive and negative voice
input
Refer to Section 3.8
If unused, keep
these pins
open.
SPK1P
SPK1N
5,
6
AO
Channel 1 positive and
negative voice output
If unused, keep
these pins
open.
Support both
voice and
ringtone
output.
SPK2P
2
AO
Channel 2 voice output
AGND
1
Analog ground. Separate
ground connection for
external audio circuits.
If unused, keep
this pin open.
Network Status Indicator
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
NETLIGHT
16
DO
Network status indication
VOHmin=
0.85×VDD_EXT
VOLmax=
0.15×VDD_EXT
If unused,
keep this pin
open.
UART Port
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
Quectel
Confidential

GSM/GPRS Module Series
M66 Hardware Design
M66_Hardware_Design Confidential / Released 19 / 80
TXD
17
DO
Transmit data
VILmin=0V
VILmax=
0.25×VDD_EXT
VIHmin=
0.75×VDD_EXT
VIHmax=
VDD_EXT+0.2
VOHmin=
0.85×VDD_EXT
VOLmax=
0.15×VDD_EXT
If only use
TXD, RXD and
GND to
communicate,
recommended
to keep other
pins open.
RXD
18
DI
Receive data
DTR
19
DI
Data terminal ready
RI
20
DO
Ring indication
DCD
21
DO
Data carrier detection
CTS
22
DO
Clear to send
RTS
23
DI
Request to send
Debug Port
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
DBG_
TXD
39
DO
Transmit data
Same as above
If unused,
keep these
pins open.
DBG_
RXD
38
DI
Receive data
Auxiliary Port
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
TXD_
AUX
29
DO
Transmit data
Same as above
If unused,
keep these
pins open.
RXD_
AUX
28
DI
Receive data
SIM Interface
PIN Name
PIN No.
I/O
Description
DC Characteristics
Comment
SIM_ VDD
14
PO
Power supply for SIM card
The voltage can be
selected by software
automatically. Either
1.8V or 3.0V.
All signals of
SIM interface
should be
protected
against ESD
with a TVS
diode array.
Maximum
trace length is
200mm from
the module
pad to SIM
card holder.
SIM_ CLK
13
DO
SIM clock
VOLmax=
0.15×SIM_VDD
VOHmin=
0.85×SIM_VDD
SIM_ DATA
11
IO
SIM data
VILmax=
0.25×SIM_VDD
VIHmin=
0.75×SIM_VDD
VOLmax=
0.15×SIM_VDD
VOHmin=
0.85×SIM_VDD
Quectel
Confidential