1.Three power input interface: DC044 interface and V_IN and a lithium battery interface.Note that: The range of DC044 and the V_IN pin voltage input is 5 – 26V, when use the 5V as the power, be sure that the power supply can provide 2A current.

The range of voltage of Lithium battery input power is 3.5 – 4.2V.

2.Switch: It is used to open / close the input power supply for the module. When in use, please confirm the toggle switched to the OPEN state (near the board inside).

3.SMA antenna interface: there is a GSM antenna interface, a GPS antenna interface onboard and a BT antenna interface.

4.Start button: When the board is power on, the LED (PWR) will light up. After a long press (about 2 second) on this button, the other three LEDs will be light. And one of them starts to flash; this suggests that SIM808 is beginning to work now. When the power supply, GSM and GPS antenna and SIM card are connected to the module correctly, the LED will be flash slowly (3Second de 1second light), that indicates that the module is registered to the network, and you can make a call or do something else.

5.TTL serial interface: a TTL level interface. Notice that: The pin of VMCU is used to control the high level of TTL UART, so as to realize to match between 1.25V/3.3V /5V systems.

6.USB interface: This interface is just use to update the firmware of SIM808 module.