Hardware Design Introduction of GSM/GPRS Module USR-GM3

Hardware Design Introduction of GSM/GPRS Module USR-GM3

1.Typical Connection

typical connection of gsm module USR-gm3

 

2.Power Interface

Working voltage VCC range from 3.4V-4.2V, 3.8V is recommended. Power the module by main power pin, pin interface is in parallel with appropriate energy-storage capacitance and high frequency capacitance.

Circuit diagram as follows

Power interface of gsm module USR-GM3

 

3.UART Interface

when the user MCU I/O level isn't 2.8V, it needs to make the level matching. DEVDD is the I/O power supply for customer MCU.V - PAD is the I/O power supply for GM3 module, users can use as UART matching and pull-up power.

Circuit diagram as follows:

UART interface of gsm module USR-gm3,circuit diagram

UART interface of gsm module USR-gm3

Note: when I/O power supply for customer MCU is 3.3v, MOD-RX pin of module don't have to level matching.

 

4.LED Output Control

The module provides LED output control and the module work status can be displayed by the LED status. Plusing power indicator is recommended.

Circuit diagram as follows:

LED Output control of gprs module USR-GM3

 

5.Reset, Reload and Wake up

Reload: Press 1s to 3s to restore user default settings, press over 6s to restore factory settings.

RESET: RESET pin connect to 10K pull-up resisitor. Press over 0.5s and release to reset the device.

WAKEUP:WAKE-UP pin connect to 10K pull-up resistor. Take effect in low level.

Circuit diagram as follows:

Reset,reload and wakeup mode of gsm module USR-GM3
 
6.Start/shutdown device interface
After module starting, closing switch to shutdown module, and disconnect switch can start module. If user doesn't need this function, this pin should be set to disconnected status.
Circuit diagram as follows:
Start and shutdown device interface of gsm module USR-GM3