PC connection: connect to a PC via a mini USB cable (tab 1);
Power connection: connect to a 6V~9V DC power supply (tab 2);
Switch to ON (tab 3)
SIM card slot: press the SIM card slot, and push the plastic sheet aside to open the slot, then, place a SIM card into it and close the slot (tab 4);
SIM908 network indicator : blinking slowly when network registration is successful (tab 5);
Connect GPS antenna (tab 6);
Arduino reset button (tab 7);
NOKIA original speaker : SIM908 1st analog voice channel output (tab 8);
Connect 3.5mm earphone (tab 9); Non-essential, you can monitor from the speaker (tab 8).
Connect with a GSM signalenhancement antenna (tab 10);
Set the jumpers (tab 11):
Connect PWRKEY to GND, see the Remarks in this section for more details.
Control the serial selection of SIM908.
CP2102 chip controlling: Connect the jumpers between USB_RX and CTL_RX, USB_TX and CTL_TX.
Arduino serial settings: Connect the jumpers between Duino_RX and CTL_RX, Duino_TX and CTL_TX.
mic: SIM908 1st analog voice channel input.
The power control of SIM908 module can be controlled by PWRKEY pin.
The switching between on and off states of the module can be controlled by connecting PWRKEY to GND for 1-2 sec and then disconnecting them.
For example, when SIM908 module is on, connecting PWRKEY to GND for 1-2 sec and then disconnecting will make the module
switch to off.
If SIM908 module is off, tying PWRKEY to GND for 1-2 sec and then disconnecting will make the module switch to on as well (similar to a warm-boot).
When PWRKEY pin is always connected to GND, SIM908 module will remain on.
Manual debugging jumper settings
Figure 2. Manual debugging jumper settings
Tab 1: Serial transmitter selection CTL_TX
Set to CP2102 chip control: Connect USB_TX and CTL_TX with a jumper.
Set to Arduino serial: Connect Duino_TX and CTL_TX with a jumper.
Tab 2: Serial receiver selection CTL_RX
Set to CP2102 chip control: Connect USB_RX and CTL_RX with a jumper.
Set to Arduino serial: Connect Duino_RX and CTL_RX with a jumper.
Tab 3: Connect the NCP2890 enable pin (SPK_EN) and earphone checking pin with a jumper.
When the Earphone socket is plugged in with a earphone cable, CHK is pulled high. It will cause SPK_EN to be pulled high and NCP2890 not enabled.
When the Earphone socket is not plugged, CHK is pulled low. It will cause SPK_EN to be pulled low and and NCP2890 enabled.
If the SPK_EN is connected to the A3 port from an Arduino board, the A3 port can enable/disable the NCP2890 chip.
Tab 4: SIM908 start up.
Tab 5: Motor control port (Motor), active-low. The RI (Ring indicator) port is low while the board is ringing.
If the Motor port is connected to the RI port, the board will vibrate in the case of receiving a phone call.
If the Motor port is connected to the A4 port from an Arduino board, the board vibration is controlled by A4 port.
Tab 6: GPS/GSM Serial mode selection
GSM_EN: if GSM_EN = 0, the GSM serial port is selected, high level by default.
GPS_EN: if GSP_EN = 0, the GPS serial port is selected, high level by default.
The GSM_EN and GPS_EN port cannot be connected to GND at the same time. Default: suspended and no serial output.
5V TTL to serial board
PC serial monitor software
PC u-center software
9V DC power supply
1. After powering up, the power indicator PWR LED will light up.
2. Select the serial chip CP2102 to control SIM908
Connect USB_RX to CTL_RX. (Figure 2. Manual debugging jumper settings. The tab 1).
Connect USB_TX to CTL_TX. (Figure 2. Manual debugging jumper settings. The tab 2).
We will illustrate the usage of the module with an example of how
to operate under GSM mode in the following section.
Connect GSM_EN to GND via a jumper, and keep GPS_EN suspended(Figure 2. Manual debugging jumper settings. The tab 6), to select GSM serial control port.
Tie PWRKEY to GND (Figure 2. Manual debugging jumper settings. The tab 4). Then, you can see that STATUS indicator remains on, and NET indicator keeps blinking, of which fast blinking means the module is trying to register to the network, and slow blinking means network registration is done successfully.
Start the TCP232 serial tool on PC, and perform operations as followed.
Figure 3. TCP232 Settings
Serial port settings
PortNum: Set to the corresponding serial port (*)
Baud rate: 115200
Data bit: 8 bit
Stop bit: 1 bit
In this example, the PortNum is set to COM1. In practical application, please right click the icon My Computer->Property->Device Manager, in order to check corresponding port number.
Check the option Auto Checksum. Then, an Appendix bits setting option box will pop up. Select the option Fixed Byte Checksum, and fill in the small box on the right of the option with 0D, since the ASCII code of CR is 0D, so that there will be an auto CR for each command transmission. The detailed settings are shown in Figure 4.
Figure 4. Data transmission settings
Fill in the transmission box with AT+GSV, and click the button Send to transmit the command.
The data receive box displays the return values from the corresponding serial port, as the figure shows:
Figure 5. Sending AT command for module verification testing
Select GSM serial control port
It can be done by connecting GSM_EN to GND with a jumper, and keeping GPS_EN suspended (see the tab 6 of Figure 2).
GSM command description
Common command descriptions for message transmission
Make sure the module is working properly
Select SMS message format
Set the message transmission number and send SMS message. After receiving the symbol >, the message Hello World!(*) can be sent out
This is a terminator. Before sending it out, you should check the option Send As Hex
(*)After sending the message Hello World!, you should check the option Send As Hex, then send the command 1A to indicate the message to be sent is end. In this case, the message you input will be delivered actually.
Common command descriptions for dialing and answering a call
Set the dialing number: 13612345678，and end with the symbol (;). Now, you can make a call
Configure GPS: first you should set the board to GSM mode (because commands should be sent under the GSM mode) and then send the commands to switch to GPS mode. Take these steps: connecting GSM_EN to GND via a jumper, and keeping GPS_EN suspended, to select GSM serial control port. Send the following commands:
AT+CGPSPWR=1 (turn on GPS power supply)
AT+CGPSRST=1 (reset to GPS mode)
GPS signal output: connecting GPS_EN to GND via a jumper, and keeping GSM_EN suspended, to select GPS serial control port. TCP232 receives relative messages, as figure 6 shows.
Figure 6. Serial message receiving under GPS mode
Checking GPS information with the software u-center
Start the software u-center2, as Figure 7 shows.
Figure 7. u-center
Open Receiver COM port: setting -> port Setting, and set the port and Baud rate: 115200 (If the Baud rate of the module is modified to a certain value by sending AT+CGPSIPR command, the modified Baud rate should be used in here).
Figure 8. COM and baud settings
Select Player to check the GPS information, as Figure 9 shows.
Connect GSM_EN and GND via a jumper, and keep GPS_EN suspended(tab 6), to select GSM serial control port。
Local virtual servers settings
Virtual servers can be used for setting up public services on your LAN. A virtual server is defined as a service port, and all requests from Internet to this service port will be redirected to the computer specified by the server IP. Please see your router's guide.
Figure 11. Local virtual servers settings
Service Ports setting: set to a no conflict port. In this example, the service port is set as 12345.
IP Address setting: Run CMD in the PC, and execute the 'ipconfig' command to confirm your IPv4 address. In this example, the IP address is 192.168.1.104.
GPRS commands descriptions
The GPRS configuration can be performed by sending out following commands sequentially:
AT Commands Descriptions
Signal quality report
Set wireless access point to CMNET
Bring up wireless connection with GPRS or CSD
Get local IP address
Query the IP address of the given domain name
Find out the PC's WAN IP, which can be obtained by searching "IP" in a search engine, or inquiring your Internet service providers directly. In this example, the WAN IP address is 22.214.171.124. Then send out following commands sequentially:
AT Commands Descriptions
AT+CIPSTART="TCP", "126.96.36.199", "12345"
The WAN IP address should be set according to actual condition. In this example, the WAN IP address is 188.8.131.52, and port number is 12345.
Send SMS message. After receiving the symbol >, the message ABCDEF 0x1A can be sent out (0x1A is the completed symbol)
Close TCP or UDP connection
Deactivate GPRS PDP context
After sending the message ABCDEF, you should check the option Send As Hex, and then send the command 1A to indicate the message to be sent is end. In this case, the message you input will be delivered actually.