STEMMA is not an original idea, we're working within an ecosystem of many other plug and play systems
We started STEMMA in 2014, and intended to be compatible with Grove only (cause that's all that existed at the time) but then when Qwiic came around in 2017, added a smaller connector so we could work with those parts too!
STEMMA attempts to be as cross-compatible as possible with both Grove and Gravity (compatible connectors & 3-5V power/logic). STEMMA QT is cross-compatible with Qwiic - STEMMA QT connector/cable is same as Qwiic. You can use STEMMA QT devices with Qwiic devices/controllers.
What doesn't work?
- Qwiic, Gravity and Grove do not always work together, see table below - most importantly: Qwiic is 3V power logic only, and does not have level shifting. Grove uses 3-5V, and only 4 pin cables for analog/digital/pwm/I2C/UART. Gravity uses 3-5V and a mix of 3 and 4 pin cables.
Controller/Device |
STEMMA |
STEMMA QT |
Grove |
Qwiic |
Gravity |
Connector |
JST 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 Voltage |
3-5V DC |
3-5V DC |
3-5VDC |
3V DC |
3-5V DC |
Logic Pins Voltage |
3-5V DC |
3-5V DC |
3-5V DC |
3V DC |
3-5V DC |
Data Protocol |
I2C only on 4 pin. Analog/Digital/PWM on 3 pin. |
I2C only |
I2C/Analog/Digital/PWM on 4 pin |
I2C only |
I2C or UART on 4 pin. Analog/Digital/PWM on 3 pin. |
Cross-Compatibility
Controller means the 'host' device, e.g. the microcontroller or Raspberry Pi computer
Device means the 'client' device, e.g. the I2C sensor, potentiometer, servo, NeoPixels, etc.
STEMMA 3/4-Pin Device |
STEMMA QT Device |
Grove Device |
Qwiic Device |
Gravity 3/4-Pin Device |
|
STEMMA 3/4-Pin Controller |
Yes |
4-Pin cable adapter (from JST PH to JST SH) required |
4-Pin STEMMA Controller will work with any Grove I2C device only. |
4-Pin cable adapter (from JST PH to JST SH) required and controller voltage must be set to 3V with solder jumper |
Yes except for 4-pin UART devices are not supported |
Grove Controller |
STEMMA 4 pin device will work on the I2C Grove ports only |
4-Pin cable adapter (from JST PH to JST SH) required |
Yes |
4-Pin cable adapter (from JST PH to JST SH) required and controller voltage must be set to 3V with solder jumper |
4-pin Gravity modules only |
Qwiic Controller |
4-Pin cable adapter (from JST PH to JST SH) required |
Yes |
4-Pin cable adapter (from Grove to JST SH) required, and Grove I2C device only |
Yes |
4-Pin cable adapter (from JST PH to JST SH) required, and Gravity I2C device only |
Gravity 3/4-Pin Controller |
Yes (STEMMA 4 pin device will work on the I2C Gravity ports only) |
4-Pin cable adapter (from JST PH to JST SH) required |
Only 4 pin Grove I2C devices will work |
4-Pin cable adapter (from JST PH to JST SH) required and controller voltage must be set to 3V with solder jumper |
Yes |
