The SCD-40 and SCD-41 have the same pinouts.

Power Pins

  • VIN - This is the power pin. To power the board, give it the same power as the logic level of your microcontroller - e.g. for a 3V microcontroller like a Feather M4, use 3V, or for a 5V microcontroller like Arduino, use 5V.
  • 3Vo - This is the output from the onboard 3.3V regulator. If you have a need for a clean 3.3V output, you can use this! It can provide at least 100mA output.
  • GND - This is common ground for power and logic.

I2C Logic Pins

The default I2C address for the SCD-4x is 0x62.

  • SCL - I2C clock pin, connect to your microcontroller I2C clock line. There's a 10K pullup on this pin.
  • SDA - I2C data pin, connect to your microcontroller I2C data line. There's a 10K pullup on this pin.
  • STEMMA QT - These connectors allow you to connectors to development boards with STEMMA QT connectors or to other things with various associated accessories.


The SCD-4x can run from 3 to 5V DC, for both power and I2C data/logic. Normally that would mean we wouldn't put a regulator and logic level shifter on the breakout. However, the SCD-4x also does best with a quiet power supply that can also supply ~200mA peak. Since that may or may not be the same as the logic power supply of the microcontroller, advanced users can customize the power/logic level setup for the sensor

On the left is the Sensor Power jumper. By default we power the sensor through the 3V regulator. If you happen to have a nice and quiet Vin power supply, you can cut and re-solder this jumper.

On the right is the level-shifted I2C logic level. Most of the time, Vin is the power and logic level for the microcontroller. However, if you are, say, powering from 5v because it's a better power supply source, but are using a 3V logic microcontroller, you can cut and re-solder this jumper.

This guide was first published on Aug 26, 2021. It was last updated on 2021-08-26 18:13:25 -0400.

This page (Pinouts) was last updated on May 24, 2022.

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