The default I2C address is 0x53.
- VIN - this is the power pin. Since the gas sensor chip may use 3 VDC, we have included a voltage regulator on board that will take 3-5VDC and safely convert it down. To power the board, give it the same power as the logic level of your microcontroller - e.g. for a 5V microcontroller like Arduino, use 5V.
- 3Vo - this is the 3.3V output from the voltage regulator, you can grab up to 100mA from this if you like.
- GND - common ground for power and logic.
- SCL (labeled SCK) - I2C clock pin, connect to your microcontroller I2C clock line. This pin is level shifted so you can use 3-5V logic, and there's a 10K pullup on this pin.
- SDA (labeled SDI) - I2C data pin, connect to your microcontroller I2C data line. This pin is level shifted so you can use 3-5V logic, and there's a 10K pullup on this pin.
- STEMMA QT - These connectors allow you to connectors to dev boards with STEMMA QT connectors or to other things with various associated accessories.
On the back of the board is one address jumper, labeled Addr. This jumper allows you to chain up to 2 of these boards on the same pair of I2C clock and data pins. To do so, you solder the jumper "closed" by connecting the two pads.
On the front of the board is one address pin, labeled SDO. Just like the jumper, this pin allows you to change the I2C address to connect multiple boards by connecting it to GND.
The default I2C address is 0x53. The other address option can be calculated by “subtracting” the Addr from the base of 0x53.
Addr sets the lowest bit with a value of 1. The final address is 0x53 - Addr which would be 0x52.
The table below shows all possible addresses, and whether the pin should be high (open) or low (closed).
- SCK - This is the SPI clock pin, its an input to the gas sensor.
- SDO - This is the Serial Data Out pin, for data sent from the gas sensor to your processor.
- SDI - This is the Serial Data In pin, for data sent from your processor to the gas sensor.
- CS - This is the Chip Select pin, drop it low to start an SPI transaction. Its an input to the gas sensor.
Please note the libraries do not support the SPI interface.