Transcript
Neo_GM650 Hardware Design Manual Version V1.4
Shenzhen Neoway Technology Co.,Ltd
Neo_GM650 Hardware design manual
V1.4
Copyright Statement Copyright © 2008 Neoway Technology All rights reserved by Shenzhen Neoway Technology Co.,Ltd.
The trademark belongs to Shenzhen Neoway Technology Co.,Ltd. Other trademarks, mentioned in this manual, are property of to their lawful owners.
Clarification This specification is aimed for use by system, research or test engineers.
With any future revisions of this product or due to other necessities, we may need to amend the content of this specification without a prior notice. Unless explicitly stated, all the information and suggestions in this manual do not carry any implied guarantees.
Shenzhen Neoway Technology Co.,Ltd can provide the needed technical support. If you experience problems, please feel free to contact the sales representative or send an E-mail to any of the following mailboxes:
[email protected] [email protected] Website: www.neoway.com.cn
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Contents 1.
Overview ................................................................ 5
2.
Appearance ............................................................. 5
3.
Block Diagram ........................................................... 6
4.
Parameters .............................................................. 6
5.
Pin Definition & Encapsulation ............................................ 9
5.1
Pin Definition ......................................................................................................... 9
5.2
PCB Packaging .................................................................................................... 13
6. 6.1.
Design Reference ....................................................... 14 Power supply & ON/OFF Interface ..................................................................... 14
6.1.1.
Power Supply .................................................................................................................. 14
6.1.2.
Power Sequencing ......................................................................................................... 20
6.1.3.
ON/OFF Pin Description ............................................................................................... 20
6.1.4.
VCCIO Pin Description .................................................................................................. 23
6.1.5.
RESET Pin Description ................................................................................................. 23
6.2.
Serial Interface ..................................................................................................... 23
6.3.
DTR and RING description ................................................................................. 26
6.3.1.
DTR Pin Description ...................................................................................................... 26
6.3.2.
RING Signal Indication .................................................................................................. 27
6.4.
SIM card interface................................................................................................ 28
6.5.
Indicator Light...................................................................................................... 29
6.6.
RF interface and PCB layout Design ................................................................. 29
6.6.1.
RF connector of GPRS part .......................................................................................... 29
6.6.2.
RF part of GPS part ....................................................................................................... 31
7.
Assembly .............................................................. 35
8.
Packaging .............................................................. 35
9.
Abbreviations........................................................... 35
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Revision Record Version
Content Revised
Effective date
V1.0
Initial version
2012-03
V1.1
Modify boot flag
2012-04
V1.2
Add UART2 pin and instructions, removed the PWM pin, and added GPS data output mode instructions.
2012-05
V1.3
Change UART2 pin number
2013-08
V1.4
Change operating temperature
2013-10
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1. Overview GM650 is an open platform wireless industrial module, supporting GSM/GPRS+GPS. It provides the user with reserved CPU resource and plenty of hardware interfaces, widely used in various industrial and commercial applications. The module has high quality voice, messaging, data connectivity, GPS location and other functions. GM650 allows two configurations for the GPS data interface: single-port and dual-port. The single port configuration is a perfect solution in cases where the user‟s MCU has only one available UART interface to support both the GPRS communication and GPS positioning functions.
2. Appearance Table 2-1 GM650 Mechanical Specifications Specifications
Description
Dimensions
30.0mm*24.0mm*2.7mm (length*width*height)
Weight
3.7g
Picture
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3. Block Diagram
PA RF Section
GSM Baseband Controller
GPS Section SIM x 2 Application Interface
Flash
Audio Section
Power Manager
LCD UART x 2 I2C MMC USB ADC/PWM
4. Parameters Table 4-1 General parameters Operating temperature
Description -40℃～+85℃
Operating voltage
3.5V～4.3V (recommended 3.9V）
Operating Current
See tables 4-2 and 4-3
Table 4-2 GSM Specifications
Description
Frequency
900/1800/850/1900 MHz
Sensitivity
＜ -106dBm
Maximum transmission power Protocol
AT
850/900 Class4 (2W) 1800/1900 Class1 (1W) Compatible with GSM/GPRS Phase2/2+
GSM07.07 Extended command set
Audio
FR、EFR、HR、AMR voice coding
SMS
TEXT/PDU
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Point to point/cell broadcast Grouped Data Circuit Switched Data
GPRS CLASS 12 Support CSD data service Support USSD
Supplement Service
Call forward（CFB,CFNA,CFU） Call waiting Threeway calling
Main Processor
ARM7-EJ@104MHz, 32Mbits SRAM, 32~64Mbits NOR Flash
Reserved software
16Mbits RAM，16~32Mbits Flash
resource Reserved software resource
UART x 2，I2C，LCD（SPI），MMC，USB，ADC，PWM， GPIO x 20，Keypad
Instantaneous Current
Max 1.8A
Average working Current
＜ 300mA
Standby Current
2.5mA typ.
Table 4-3 GPS Specifications
Description
GPS C/A coding
1.023 MHz chip rate
GPS Channel
48 channels tracking
GPS Sensitivity
-162dBm
Position Accuracy
10m
Speed Accuracy
0.01 m/s
Time Accuracy
Synchro with GPS Satellite time（<60ns）
Time of hot start
<1s
Time of warm start
<35s
Time of cold start
<35s
Time of recapture
<0.1s
GPS data updating
2Hz
frequency
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Height limit
18288m
Speed limit
515 m/s or 1854Km/h
Acceleration limit Average working current
<4g ＜ 38mA
（tracking mode） Average working current
＜ 45mA
（getting posotion）
Note: The starting time, working current and other GPS parameters relate to the testing environment, including whether is under open sky, thickness of the clouds and so on.
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5. Pin Definition & Encapsulation 5.1 Pin Definition The signal connection uses 74 SMD pads of stamp-hole type (half hole).
Note: GM650 module IO interface level is 2.8V. The module‟s internal IO uses 2.8V power supply system, which sets the input voltage for all IO pins must not exceed the maximum of 3.3V, otherwise it may damage the module‟s IO. Possible signal integrity problems in circuits using 3.3V power may lead to overshooting and output voltages surpassing the 3.3V limit and rising as high as 3.5V sometimes. Such situation will cause damage to the IO port if a 3.3V signal is directly connected to the 2.8V module IO. Hence a level matching external circuit should be used to properly interface with the IO port. Please refer to chapter 6.2 for more details.
Table 5-1 GM650 Pin Definition Pin
Signal Name
I/O PWR
Function Description
1
GND
2
Reserved
Ground Reserved
3
Reserved
Reserved
4
URXD1
DI
5
UTXD1
DO
UART1 input UART1 output
data
receive
data
transmit
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Remark
Used for GPRS communication and AT commands
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Neo_GM650 Hardware design manual V1.4 DO UART2 data transmit 6 UTXD2
In dual-port mode carries the GPS data; Unused in single-port mode
output; baud rate = 9600 Reserved
7
NC
8
Reserved
9
GND
10
Reserved
Reserved
11
Reserved
Reserved
12
VCCIO
AO
2.8V output
Can be power supply for the IO level shifting circuit; Load capacity <50mA
13
VRTC
PWR
RTC power
2.8V，the highest output current is 2mA
14
BACK_LIGHT
working station indicator, output square signal of 0.5s high level, 1.5s low level
High level light LED; needs a capacitor of 0.1uF connected in parallel
15
Reserved
Reserved
16
Reserved
17
RESET
Reserved Reset
18
Reserved
Reserved
19
Reserved
Reserved
20 21
GND ANT_GSM
PWR I/O
Ground GSM antenna interface
22
GND
PWR
Ground
23
DTR
DI
24
Reserved
25
Reserved
Reserved Reserved
26
Reserved
Reserved
27
KCOL0
DI
Keyboard column scan 0
While using the serial interface to update software version, pin27 KCOL0 must be set at high level
28
ON/OFF
DI
ON/OFF input
Low level pulse changes ON/OFF state; Keep in high level; Refer to chapter 6.1.3
29
Reserved
Reserved
30
Reserved
Reserved
31
Reserved
Reserved
DO PWR
DO
DI
Must be left floating
PWM output
Must externally connect a 100k pull-down resistor
Ground
Soft reset input, low level reset
RF
Low power consumption set
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Refer to chapter 6.3
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the
Neo_GM650 Hardware design manual 32 33 34 35 36 37 38,39
RING Reserved
DO
Ring output Reserved
Reserved Reserved
Reserved Reserved
Reserved GND
PWR
Reserved Ground
VBAT
PWR
Main Power
40
Reserved
Reserved
41
Reserved
Reserved
42
Reserved
Reserved
43
Reserved
Reserved
44 45
GND Reserved
46
Reserved
Reserved
47
Reserved
Reserved
48
Reserved
Reserved
49
VSIM1
50
PWR
V1.4 Refer to chapter 6.3
3.5V~4.3V，recommended 3.9V
Ground Reserved
PWR
Power of SIM card 1
SIM1_CLK
DO
Clock of SIM card 1
51
SIM1_RST
DO
SIM card 1 reset
52
SIM1_DATA
DIO
Data input/output of SIM card 1
53
GND
PWR
Ground
54
MICP
AI
Positive electrode MIC audio input
of
Alternating peak voltage ≤200mV
55
MICN
AI
Negative electrode MIC audio input
of
Alternating peak voltage ≤200mV
56
EARN
AO
Positive electrode of earphone audio output
32Ω earphone driving output
57
EARP
AO
Negative electrode of earphone audio output
32Ω earphone driving output
58
SPKN0
AO
Negative electrode speaker output
of
Maximum 0.9W@8Ω
59
SPKP0
AO
Positive electrode speaker output
of
Maximum 0.9W@8Ω
60
Reserved
Reserved
61
Reserved
Reserved
62
Reserved
Reserved
63
Reserved
Reserved
64
Reserved
Reserved
65
GND
PWR
Compatible cards
with
1.8/3.0V
SIM
Built-in 5k pull-up resistor
Built-in resistor
internal
100k
pull-up
Ground
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Neo_GM650 Hardware design manual Reserved Reserved 66 67
Reserved
Reserved
68
Reserved
Reserved
69
Reserved
Reserved
70
CLK32K
71
Reserved
Reserved
72
Reserved
Reserved
73
GND
74
ANT_GPS
DO
PWR I/O
32.768kHz clock output
V1.4
real-time
Ground GPS antenna interface
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RF
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5.2 PCB Packaging The signal connections use 74 SMD pads of stamp-hole type (half hole) and pitch of 1.27mm. The PCB encapsulation we recommend is as in figure 5-1. Dimensions in millimeters.
Figure 5-1 Recommended PCB footprint（top view） Note：The number in the brackets stands for coordinate position of the pad. Origin point is the center of the module. The number below the coordinate stands for shape size of the pad‟s LxW. The top right corner and the bottom right corner are two circle regions (R=1.3). The circle All rights reserved by Shenzhen Neoway Technology Co., Ltd
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regions are route keep out regions. For the routing requirements refer to chapter 6.6.
6. Design Reference 6.1. Power supply & ON/OFF Interface Table 6-1 Power supply & ON/OFF Interface
12
Signal Name VCCIO
PWR
2.8V power output
Can be power supply for the IO level shifting circuit; Load capacity <50mA
13
VRTC
PWR
2.8V
17
RESET
DI
RTC power input Reset input
28
ON/OFF
DI
38-39
VBAT
PWR
Pin
I/O
Function Description
Remark
Soft reset input, low level reset
ON/OFF input，low level pulse changes the ON/OFF state Main power supply input
3.5V~4.3V
6.1.1. Power Supply VBAT is the main power supply of the module, with power input in the range of 3.5V~4.3V. The recommended operating voltage is 3.9V. VBAT supplies power to all digital signal and analog signal sub-systems in the module as well as to the RFPA.
The performance of VBAT will directly affect the performance and stability of the whole module. The average power consumption of the module is below 1.2W, but the maximum instantaneous current on the VBAT pin is 1.8A. In the power circuit, it is needed to add a high
capacity
aluminum
electrolytic
capacitor
or
a
lower
capacity
tantalum
electrolytic capacitor to strengthen the instant large current free-wheeling ability of the power. The higher the capacity is, the lower maximum current of the power output needs to be.
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It is also needed to add filter capacitors of 0.1uF, 100pF and 33pF to reduce the influence of the radio frequency interference. Add a capacitor of low impedance and high capacity near to the module. The detailed testing data is as the following picture:
Figure 6-1
The data above is related to the equivalent impedance of the capacity and the internal resistance of the power. For C1 we recommend to use a 1000uF aluminum electrolytic capacitor of low impedance. A 470uF tantalum electrolytic capacitor can be used instead, if the space is limited. If the power is supplied by lithium battery directly, C1 could be a 220uF or 100uF tantalum capacitor.
Maximum current is drawn during calls with weak signal or data transmission process.
Typical current and voltage curve is as below:
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Figure 6-2
The power design of VBAT should ensure that the instantaneous current can‟t be lower than 3.5V, otherwise the module will not work properly. The main power supply can‟t exceed 4.3V, otherwise will cause damage because of overvoltage. The recommended voltage for VBAT is 3.9V.
In remote applications or conditions with high electromagnetic interference, it must be ensured that the power is ON/OFF controlled. Use the EN pin of LDO or DC-DC to control the power ON or OFF. If there is no controlling switch in the power system, please refer to figure 6-3 for a P-MOSFET electronic switch. According to it, when GPRS_EN is high level, the switch will be on.
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Figure 6-3
Adding Q2 is to supply Q1 with level, high enough (not lower than 3.9V), to ensure that the P-MOSSFET will work reliably. If the external controlling signal of MCU can be equal to or than VDD3V9, the Q1,R1,R2,R4 could be removed and the switch controlled by a low level, for “on” state. Q1 uses IRML6401, or other low internal resistance (Rds) type of P-MOSFET with an external high value resistor to limit the current drain in on state. Q2 uses a normal NPN transistor (e.g.MMBT3904) or NPN digital transistor with built-in bias resistors (e.g. DTC123). When using the digital transistor, R1 and R2 can be removed from the circuit. C4 uses a 470uF tantalum electrolytic capacitor, rated for voltage higher than 6.3V. Alternatively a 1000uF aluminum electrolytic capacitor could be used instead. It is strongly recommended to add a zener diode for protection. For example MMSZ5231B1T1G made by ON Semiconductor or PZ3D4V2H made by Prisemi.
On the PCB, please keep the radio-frequency signal as far away as possible from the VBAT power supply section. The track width should meet the 2A current and the voltage in the loop should not decrease. Based on that, the track width at the main power of VBAT should be about 2mm. The ground plane in the power supply section should be as smooth as All rights reserved by Shenzhen Neoway Technology Co., Ltd
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possible, and ground holes are recommended.
If problems arise under low temperature conditions, the highest failure rate will probably be in the power supply section. The power supply ripple increases with the decrease of load capacitance. Under low temperature conditions, the activity in the electrolytic capacitors will lead to decrease in their capacitance, ESR will increase, and that will weaken the filtering effect. It is recommended to use electrolytic capacitors which have good performance under low temperature conditions or under high pressure conditions or enlarge the total capacitance. A proper capacitor with its capacity and impedance should be carefully selected. So please be careful when you design the product to work under low temperature conditions especially considering the power supply section.
Prohibit the use of power from the diodes‟ voltage drop directly since it will enlarge the diode‟s voltage drop tremendously under the low temperature conditions, and that will lead to great power supply fluctuations which can make the module unstable.
When you are testing the static electricity and surge, please ensure the stability of the power supply. Some EMC design may be considered to add to the input and output interfaces in order to avoid the burr and peak. It is recommended to properly increase the filtering capacitors to ensure the power supply stability. For example, some 1~4.7uF ceramic capacitors could be added in parallel.
VRTC is power supply pin of the real-time clock (RTC). When the VBAT supply works well, VRTC will continuously output 2.8V voltage. The modules can apply to charge button batteries or a bulk capacitor. The current is 2mA. When the VBAT is off-power, the button batteries or bulk capacitor can power the RTC to keep the RTC clock work properly. The capacity of energy storage capacitor should be as large as possible. If the 100uF tantalum electrolytic capacitors are used in the system, it can keep the clock working for 1 minute after the shutting off the VBAT. All rights reserved by Shenzhen Neoway Technology Co., Ltd
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Please refer to figure 6-4:
Figure 6-4
VRTC can also be designed in a way as in figure 6-5:
Figure 6-5
If the module ran into a problem in a low temperature of -40°, the problem will be most probably caused by the power supply, and will expressed in the increase of the power supply ripples and the decrease of the load capacitance. If the lowest point in the ripples is lower than or close to 3.3V, the module will automatically shut down to for protection. In addition, if the power is supplied from a DC/DC converter, the performance of IC and any inductors will vary significantly under temperatures of around -40°. Therefore, when designed for ultra-low temperature applications, the power supply circuit requires caution.
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It is forbidden to supply the power by diode direct buck. That may cause unstable operation of the module.
6.1.2. Power Sequencing
Figure 6-6 Power Sequencing
Note: Module‟s main power supply shouldn‟t be powered on earlier than the external MCU. Please ensure that the module is powered on after the MCU in order to guarantee its stable work.
6.1.3. ON/OFF Pin Description The ON/OFF pin is an input, controlled by external signal. The input has active low level. All rights reserved by Shenzhen Neoway Technology Co., Ltd
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Power on process: When the module is in the shutdown mode, first pull the ON/OFF base pin down to low level and maintain for more than 300ms (recommended for at least 500ms), then pull the ON/OFF base pin up to a high level, to start the module. (figure 6-6). When the module is powered on, the module's serial port will automatically output "+ EIND: 1", said the module has started successfully and is now controllable by AT commands. The VCCIO will start to continuously output 2.8V. Power off process: Under the start-up mode, if the ON/OFF is high level, this time pull low the ON/OFF pin and maintain for 300ms (recommended for at least 500ms), then the module will enter the shutdown process to disconnect from the network, it usually takes about 5 seconds for the module to completely shut down and then the main power turned off; If the ON/OFF is low level, pull the ON/OFF up for some time before the execution of the shutdown sequence described above. An AT command can also be used to shut the module down; please refer to the AT command manual. If you want to change the switch electrical and mechanical level, an inverter should be used. Figure 6-7 shows the recommended GM650 power on/off circuit with high level active input:
Figure 6-7 Recommended high level power on circuit
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The GM650 ON/OFF is low level effective. After the level inversion above, the USER_ON is high level on. The ON/OFF pin can also be connected to GND for simplicity. The module will automatically be on after power on in that case. A proper control of the ON/OFF pin by the user‟s software must be ensured in order to guarantee the module‟s operation.
Note: ON/OFF base pin has the function of start-up and shut-down, thus be careful to avoid repeated triggering which will result in confusion of start-up or shut-down. For example, if the user wants to start up, but a 300ms high pulse is issued twice to the ON/OFF pin, the module will shut down immediately after start up.
Furthermore, pay attention to external MCU and module connection interface level, especially UART, which may affect the module boot timing. For example, when starting up, the external MCU has an IO port in output state while the same port is the module‟s UART port UTXD signal (which is also an output pin), the module may be unable to start up.
Also note that, if the module has voltage on some input before starting up, it may also affect the boot timing. If you provide the module VBAT supply and then use the ON/OFF signal, it may cause a start-up failure. Therefore, in order to guarantee reliable start-up process, it is recommended that the ON/OFF should be in low level first, and then give the module VBAT supply. Then after the module has started completely, pull the ON/OFF control pin back to a high level.
The ON/OFF controls the module‟s internal software. If the module has not started properly, it may be unable to respond to the ON/OFF pin anymore and a forced VBAT power disconnection should be used in such case.
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6.1.4. VCCIO Pin Description Pin 12 VCCIO is the 2.8V IO interface voltage, which the module supplies to an external circuit. It has a load capacity of 50mA and is suggested to be used for level shifting interface only. In power off state then VCCIO output also off. Moreover, this pin can be used to indicate the running state of the module. When running normal or in sleep mode, the pin is kept at high level 2.8V, while in power off modem, the pin is low level.
6.1.5. RESET Pin Description Pin 17 of GM650 is RESET input pin. The module will reset on low lever on this pin. This pin controls the module‟s internal software and in case of a software crash due to improper operation, it may not be able to trigger reset.
6.2. Serial Interface Table 6-2 Serial interface Function Description
PIN
Signal Name
I/O
4
URXD1
5
UTXD1
DI DO
UART1 data receiving UART1 data transmitting
7
UTXD2
DO
UART2 data transmitting, baud rate= 9600
Remark
Dual-port mode: used to receive GPS data; Single-port mode: unused.
The serial interface is usually used for AT commands, data services, module firmware updates and so on. The module is a DCE device. The connection signals with a terminal device (DTE) are shown in the following picture:
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Figure 6-8 Connection between DCE and DTE The serial interface of GM650 is 2.8V CMOS; the maximum input level is 3.3V. Supported baud rates are: UART1: 1200，2400，4800，9600，19200，38400，57600，115200; default is 115200bps. UART2: 9600. In dual-port mode used to output GPS data. In single-port mode UART2 is unused. If the main power supply for the external MCU is 3.3V, a 200~330ohm resistor is recommended in series to the module. In the PCB layout, this resistor should be placed close to the output of the signal source, while the capacitor should be placed close to the module on the receiving end. Refer to the following figure:
Figure 6-9 3.3V MCU communication via serial interface A 100pF or 200pF filter capacitor should be placed close to the module receiver pin. The values of the resistors and capacitors can be selected based upon the measured signal All rights reserved by Shenzhen Neoway Technology Co., Ltd
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waveform. Greater the resistance and capacitance values will provide higher attenuation, but also will lead to greater signal delay or signal waveform distortions and lower baud rates on the serial communication, Therefore, the resistance and capacitance should be carefully selected. When the user‟s external MCU voltage is 5V, the serial interface needs to be level-shifting as in the reference circuit below:
Ficure 6-10 5V MCU communication via serial interface
“INPUT” connects to the external MCU‟s TXD, “VCC_IN” is the external MCU‟s 5V power supply, “OUTPUT” connects to the GM650„s RXD input, and “VCC_OUT” is provided by the module‟s VCCIO (2.8V) output. Another copy of the level-shifting circuit must be used in the second communication wire. The R3 is a 4.7K~47K resistor and R2 is a 3.3K~10K resistor. Resistance selection is related to the supply voltage and the serial port baud rate. When the supply voltage is higher or the baud rate is lower, the resistors can be of higher resistance which will lead to lower power consumption. Q1 may be an ordinary NPN transistor (for example, MMBT3904) or built-in bias resistors NPN digital transistor (for example DTC123). When using the digital transistor, R2 can be removed from the circuit.
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Note: Avoid serial data generated when the module is powering up. Data to the module should only be sent after the completion of the module‟s start-up procedure (at least 2s). The purpose is to avoid forcing the module into a wrong mode of operation. Take care to avoid crosstalk between the TXD and RXD lines by keeping them apart with spacing at least 3 times the track width. Avoid running the lines in parallel to each other for long distances, and where possible run a ground plane close to these lines to avoid interference. Use through holes to link the ground planes on the various layers.
6.3. DTR and RING description Table 6-3 PIN
Signal Name
I/O
Function Description
32
RING
DO
Ring output
23
DTR
DI
Low power consumption mode controlling input
Remark
6.3.1. DTR Pin Description DTR is the low power control pin, and if not required can remain unconnected. For low-power usage, please see the AT commands. Using AT command to enable the low power capabilities, set DTR pin to low, if the module is idle, then enter low-power mode. In low power mode, the standby current is approximately 2.5mA. In low power mode, the module will timely respond the call, SMS and data services. External MCU can control module hardware IO (DTR pin) to exit the sleep mode.
Basic process for entering the sleep mode: 1)
Keep the module DTR input high while issuing the AT command to allow entering sleep
mode (refer to the AT command AT+ENPWRSAVE). In this mode, the run light stops flashing. 2)
Pull the DTR input low. Typically the module will enter sleep mode in about 2 seconds.
In sleep mode, the serial port of the module is disabled and will not respond to data. The All rights reserved by Shenzhen Neoway Technology Co., Ltd
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module will only enter into sleep mode, if there is no data present on the serial port, otherwise the module will wait until the completion of the current data transfer to end before entering sleep mode. 3)
If the serial port has data the MCU can place DTR high. The module will immediately
exit sleep mode and within 50ms will be back to normal operation mode, and the serial port will respond to AT commands. After the completion of the calling service, the external MCU may pull DTR low and place the module into sleep mode again. 4)
In sleep mode, if the module received calls, messages or data from the server, it will
immediately exit sleep mode and output call information through the serial port. After the external MCU has detected activity on the serial port, the DTR line should be set high, to process calls, data etc. When processing is complete, the module will go into sleep mode upon DTR being set low. If there is a call, and DTR is not set high, no data will be transmitted over the serial port and the module will automatically enter into sleep mode in approximately 2 seconds.
6.3.2. RING Signal Indication 1)
Voice calls:
For incoming voice calls, the UART port will transmit a "RING" string while the RING pin will cycle in 4s pulses with the line kept in low level for 250ms during each cycle for the whole ringing time. It will revert back to constant high level after the call is connected. Please refer to the figure below:
Figure 6-11 Voice calls RING indication All rights reserved by Shenzhen Neoway Technology Co., Ltd
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2) SMS: Incoming SMS will be indicated with a single 200ms pulse.
Figure 6-12 SMS indication
6.4. SIM card interface Table 6-4 Pin
I/O
SIM card interface
49
Signal Name VSIM1
PWR
Function Description SIM card1 power supply
50
SIM1_CLK
DO
SIM card 1 clock
51
SIM1_RST
DO
SIM card1 reset
52
SIM1_DATA
DIO
SIM card1 data input/output
remark 1.8/3.0V
Ficure 6-13 SIM card interface design GM650 module supports 3V and 1.8V SIM cards. VSIM is the power supply pin for SIM card with load capacity up to 30mA. This power output only operates when the module works with the SIM card. The SIM_DATA line has an internal 5k pull-up resistor and does not require any externally All rights reserved by Shenzhen Neoway Technology Co., Ltd
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connected pull-up resistors. The SIMCLK line is the SIM card clock, normally 3.25MHz. The PCB clock distribution track must be kept smooth and in one piece. It has to be as short as possible, surrounded with ground and kept away from the antenna and other RF components. The capacitance (containing the junction capacitance of the ESD device) of this signal cannot be over 100pF. It is recommended to have the SIM card circuit close to the card connector. Except for the VSIM pin, which uses a 0.1uF capacitor, the other SIM card pins shall have 27~33pF capacitors to ground (refer to figure 6-11). This capacitance shall be put as close as possible to the relevant pin of the SIM card. Note：Small filter capacitance is mainly to prevent any interference from the antenna when it is too close to the module and the SIM card and otherwise may result the card will not be read normally or the antenna‟s reception sensitivity got worse, especially when using a short rubber antenna or internal antenna.
6.5. Indicator Light Table 6-5
Indicator light
Pin
Signal Name
I/O
Function Description
14
BACK_LIGHT
O
Working state indicator
remark
When the module is operating, the indicator light will be on for 0.5s and off for 1.5s. Note: Connect a 0.1uF capacitor in parallel with the BACK_LIGHT pin.
6.6. RF interface and PCB layout Design The GPRS RF and GPS RF sections should be as far away from each other as possible, including all participating tracks in the PCB layout and the antennas.
6.6.1. RF connector of GPRS part Pin 21 is GSM RF interface with impedance of 50Ω and can be connected to a ZYJB, sucker antenna, built-in PIFA antenna or other type antenna. The RF track should conform to the necessary rules in order to avoid signal interference. All rights reserved by Shenzhen Neoway Technology Co., Ltd
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The antenna used should have a standing-wave ratio of 1.1~1.5 and input impedance of 50Ω. The requirements towards the antenna vary with the environment. In general, higher the intra-band gain results lower out band gain and a better performance of the antenna.
When using multi ports antenna, the isolation between each port should be more than 30dB. If there is a RF PCB track between the module and the antenna, it must be 50Ω impedance controlled and the length should be as short as possible.
If a longer antenna track is needed, please add a π-matching network as in the picture below.
Ficure 6-14
In two layer boards the RF track should be as short as possible. The suggested parameters ate: width of 0.8~1.0mm, and the space between RF and the ground about 1~0.8mm. The RF track should be short and smooth. Please refer to figure 6-15, which demonstrates a two layer board application. The RF signal connects to GSC RF connector via PCB track, and the antenna is connected to the board via cable.
There shouldn‟t be any tracks right under the GPRS module.
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RF testing point is at PCB projection area. It is needed to have a copper dug area with a diameter of 1.4mm. There shouldn‟t be any track in this area. There should be isolation between this area and the copper dug area of pin 57 and shouldn‟t be any track or copper in the top layer, the second layer needs to be a copper area. The other PCB layers can contain tracks. RF wiring width of 0.8~1mm, length as short as possible, clearance to the ground of 0.8~1mm, wiring around need to dig full ground holes.
Module RF test point to dig copper area should be isolated by ground against RF wiring to dig copper area. Figure 6-15
Pins 20 and 22 need to connect to ground on both sides completely, no half-connect ground conditions.
Module RF test point below the surface needs to dig copper, about 1.5mm in diameter and should be surrounded by paved ground.
Note: The RF signal and RF components in the user's system should be located away from the high-speed circuits, switching power supplies, power transformers, large inductance and single-chip clock circuits.
6.6.2. RF part of GPS part Pin 74 is RF GPS interface, PCB layout impedance requirement is for 50Ω with the RF track as short as possible. Users can refer to the GSM section for more details. The requirements towards the GPS routing are even tougher because the GPS air wireless signal strength is
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lower which results in weaker electrical signal which the antenna receives. Weaker signals are more susceptible to interference.
A ceramic GPS chip antenna can be used. It is suggested to use an active antenna. From the antenna the GPS satellite signal, passes through the active antenna front-end LNA (low noise amplifier) to be amplified, then goes through the connector and a PCB layout track fed into GM650‟s pin 74. The connector and the PCB tracks, require 50Ω impedance control, and tracks to be as short and smooth as possible.
For users with advanced RF design skills and doing multilayer PCB, a passive ceramic or other type of GPS antenna design can be implemented with a proper routing and thorough testing. Passive GPS antennas may reduce the BOM cost, but require better understanding the matter in order to produce a reliably working board.
Figure 6-16
The figure below is a practical implementation of an LNA circuit design for GM650, which has been used in a product and possesses excellent performance.
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Figure 6-17
If the antenna and the PCB layout are not properly designed, the sensitivity of the GPS will decrease leading to low positioning accuracy or long signal acquisition times.
Re-emphasis, GPRS and GPS RF sections, including the PCB layout tracks and antenna, must be placed as far away as possible to prevent these two parts from interfering with each other.
6.7. GPS data interface mode instructions GPS data can be fed into the user‟s application by using one of the two possible modes for the serial interface.
6.7.1. Single-port mode GPS data is sent to the GPRS baseband chip and available via AT commands to the user‟s MCU via CM650‟s UART1. The user has indirect access to the GPS data. For the related All rights reserved by Shenzhen Neoway Technology Co., Ltd
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AT-command please see GM650 module AT command set. GM650 has only one UART interface for the user which is suitable for MCUs that have only one available UART port to support both GPRS communications and GPS positioning.
UTXD1 URXD1
Figure 6-18
6.7.2. Dual-port mode In dual-port mode, GM650 provides two independent UART interfaces: UART1 for GPRS communications and AT commands and UART2 for GPS data. UART2 outputs GPS data in NMEA-compliant format with baud rate 9600bps.
Figure 6-19 Dual-port model, GM650 provides two independent UART interfaces.
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6.8. Module hardware design considerations When using the serial port to download, the pin 27 KCOL0 must be kept at high level, otherwise the download cannot be initiated.
7. Assembly The GM650 module uses 74 SMD pads of stamp-hole type (half hole).
8. Packaging In order to prevent the product of from being affected with damp, caused by using the SMT way to perform the furnace welding, in the process of production and use of the costumer, we employ the way of damp-proof packing, such as Aluminum Foil Bag, desiccating agent, Humidity Indicator Cards, Suck plastic trays, and vacuolization. As a result the product is kept dry and its life span will be long. In order to make the SMT way easy, we use the tray to load the product. The user only needs to install it in the chip mounter according to the fixed direction. For GM650 storage and SMT notes please refer to
.
9. Abbreviations ADC
Analog-Digital Converter
AFC
Automatic Frequency Control
AGC
Automatic Gain Control
AMR
Acknowledged multirate (speech coder)
CSD
Circuit Switched Data
CPU
Central Processing Unit
DAI
Digital Audio interface
DAC
Digital-to-Analog Converter
DCE
Data Communication Equipment
DSP
Digital Signal Processor
DTE
Data Terminal Equipment
DTMF
Dual Tone Multi-Frequency
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DTR
Data Terminal Ready
EFR
Enhanced Full Rate
EGSM
Enhanced GSM
EMC
Electromagnetic Compatibility
EMI
Electro Magnetic Interference
ESD
Electronic Static Discharge
ETS
European Telecommunication Standard
FDMA
Frequency Division Multiple Access
FR
Full Rate
GPRS
General Packet Radio Service
GSM
Global Standard for Mobile Communications
HR
Half Rate
IC
Integrated Circuit
IMEI
International Mobile Equipment Identity
LCD
Liquid Crystal Display
LED
Light Emitting Diode
MS
Mobile Station
PCB
Printed Circuit Board
PCS
Personal Communication System
RAM
Random Access Memory
RF
Radio Frequency
ROM
Read-only Memory
RMS
Root Mean Square
RTC
Real Time Clock
SIM
Subscriber Identification Module
SMS
Short Message Service
SRAM
Static Random Access Memory
TA
Terminal adapter
TDMA
Time Division Multiple Access
UART
Universal asynchronous receiver-transmitter
VSWR
Voltage Standing Wave Ratio
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