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SIM808 GSM/GPS module: specs and pinout

Module built around the SIMCom SIM808 chip: quad-band GSM/GPRS, a GPS receiver and Bluetooth, controlled by AT commands over a serial port.

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Specs

Power

Chip pins

These are the pins of the chip on the module, from the chip datasheet. The module's own header may label or expose them differently.

The module board (regulator, level shifting, antenna connectors, supply input, header order) is not covered by an official document; the rows are the chip's serial and USB pins from the SIMCom hardware design.

Build with it

Project ideas for the SIM808 GSM/GPS module. Each link opens Soldr with the prompt filled in; Soldr assigns the pins, checks power and shows how to wire every part.

• GPS bike tracker with SMS location: Track your own property only; never track a person without their consent. Power the SIM808 from its own protected single 18650 cell: the cell goes through the 1S 3.7 V 3 A protection board, whose 3 A rating is above the 2 A transmit burst the SIMCom document requires (section 4.1); check the cell's own discharge rating covers 2 A, and that the module board's supply input accepts the cell voltage (3.4-4.4 V at the chip). Run the ESP32 from its own USB supply, not from this cell, and join the grounds. Check the module's serial level before wiring it to the ESP32.
• Remote temperature reporter: A place with no Wi-Fi can still report by SMS. The module's chip works down to -40 C, but the battery does not; keep the pack indoors. Learning project. Power the SIM808 from its own protected single 18650 cell: the cell goes through the 1S 3.7 V 3 A protection board, whose 3 A rating is above the 2 A transmit burst the SIMCom document requires (section 4.1); check the cell's own discharge rating covers 2 A, and that the module board's supply input accepts the cell voltage (3.4-4.4 V at the chip). Run the ESP32 from its own USB supply, not from this cell, and join the grounds.
• GPS position display: The chip's GPS engine outputs NMEA over the serial port; the ESP32 parses it and shows latitude and longitude on the I2C display. Learning project. Power the SIM808 from its own protected single 18650 cell: the cell goes through the 1S 3.7 V 3 A protection board, whose 3 A rating is above the 2 A transmit burst the SIMCom document requires (section 4.1); check the cell's own discharge rating covers 2 A, and that the module board's supply input accepts the cell voltage (3.4-4.4 V at the chip). Run the ESP32 from its own USB supply, not from this cell, and join the grounds.

Common mistakes

• Under-powering it: transmit bursts draw peaks up to about 2 A and the chip may shut down if VBAT falls below 3.0 V (source: link, section 4.1 Power Supply, p.20)
• Putting a 3.3 V or 5 V host signal on the serial pins without checking: the chip's serial pins are in a 2.8 V domain (VIH 2.5-2.8 V); check what level shifting the board has (source: link, Table 11)
• Not syncing the baud rate: autobauding is the default, and the host must send AT until it receives OK (source: link, section 4.6.1)

Not covered by the official source

• The module board is not documented by SIMCom; its supply input, logic level and header labels are not given.
• Check that 2G service is available where you use it before relying on SMS or GPRS.
• The 3 A rating of the protection board and the discharge rating of the 18650 cell are not from a maker document; check the markings on the parts you use.

Sources

• link (SIMCom SIM808 Hardware Design V1.00, 2014-03-27)