Sciotronics
Mecha Comet
microbots io

Sparkfun micromod
Adafruit Stemma
Arduino Modulino

Sparkfun Qwiic

Controller/DeviceSTEMMA
STEMMA QTGroveQwiicGravity
ConnectorJST PH 3 or 4 Pin (2.0mm pitch)JST SH 4 Pin (1.0mm pitch)Proprietary 4 Pin (2.0mm pitch)JST SH 4 Pin (1.0mm pitch)JST PH 3 or 4 Pin (2.0mm pitch)
Power Pin Voltage3-5V DC3-5V DC3-5VDC3V DC3-5V DC
Logic Pins Voltage3-5V DC3-5V DC3-5V DC3V DC3-5V DC
Data ProtocolI2C only on 4 pin. Analog/Digital/PWM on 3 pin.I2C onlyI2C/Analog/Digital/PWM on 4 pinI2C onlyI2C or UART on 4 pin. Analog/Digital/PWM on 3 pin.