Customer:
I am using the MQ-131 easyC gas sensor with a Seeeduino XIAO (SAMD21). After connecting the sensor via easyC to my microcontroller, my microcontroller stops functioning. I tested with the 5V pin from my microcontroller connected to the sensor and the problem remained. I tested multiple sensor boards and other microcontroller models, and the issue persists across all configurations. Can you clarify if this is expected behavior and how the gas sensor should be used?
Originally submitted via email support on 12 February 2025. Migrated to the forum for community visibility.
Soldered Support:
Do not use the programming pins on the breakout—those are only for programming the onboard ATTINY1604. The only correct way to connect this breakout is via the easyC/qwiic cable. The board has voltage-level translation that allows it to work with both 3V3 and 5V microcontrollers.
The easyC connector pinout is: GND, 3V3 (or 5V), SDA, SCL. When viewing the board from above with the MQ sensor oriented south and the UPDI pins oriented north, this describes the left easyC connector.
Please verify your connection pinout matches our easyC connector standard, as the Seeeduino XIAO has no specific connectors and requires careful alignment.
If your microcontroller stops working, the cause is likely a short circuit. A normal I2C device should not stop a microcontroller’s function. The default I2C address of our easyC products is 0x30, and this can be changed via the on-board switch. You can also change the address in the library when initializing the object. Try adjusting the connection pinout and the I2C address configuration.
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