Humminbird 778c HD COM port gps NMEA pinouts

The pinout for the COM connector for our units is attached.

Do not connect anything to the +12VDC output though as you could cause internal circuitry damage to the 778cX HD unit. This is meant to power the Humminbird brand accessories and may not be able to provide the power levels that other devices need. It looks like your device is powered by 5 volts, connecting it to the 778cX HD unit may have caused it damage as we output 12 volts and not 5 volts as your data suggests.

The USB Pinout:

Pin	Name	Cable color	Description
1	VCC	Red	+5 VDC
2	D-	White	Data -
3	D+	Green	Data +
4	GND	Black	Ground

The GPS reveives +5 VDC and the sonar COM port provides +12 VDC
Dont ever connect the GPS on this port without converting the voltage to +5 VDC first, otherwise you burn your GPS AND your sonar COM port.