https://devzone.nordicsemi.com/f/nordic-q-a/122668/thingy-91x-i2c-bus-faulting-with-multiple-devicesHello Team, i am trying to read multiple mcp9600 on the nrf9151 on my thingy 91x. I connected 3 of the mcp9600 to my stemma QT connector and it all works fine. However, when i connect a fourth mcp9600 to my i2c bus, the signal on my SDA line completelyen-USTelligent Community 13Thu, 03 Jul 2025 08:08:16 GMThttps://devzone.nordicsemi.com/thread/541280?ContentTypeID=1Thu, 03 Jul 2025 08:08:16 GMT137ad170-7792-4731-bb38-c0d22fbe4515:6896c06c-4d85-4e30-9521-fad5d25e5d57Constantin<p>i removed some of the 10k pull ups from the breakout boards and it works like a charm now!</p> <p>Thank you so much</p><div style="clear:both;"></div>https://devzone.nordicsemi.com/thread/541253?ContentTypeID=1Thu, 03 Jul 2025 06:26:49 GMT137ad170-7792-4731-bb38-c0d22fbe4515:c7b25ad9-314a-4436-8b2a-8657b10e0c4bSusheel Nuguru<p><span>Thanks for the details, Constantine. I think that this is the behavior of Thingy91x built-in MOSFET I2C level shifter which only works reliably when the pull-ups on each side are kept weak (typically 10 kohm) and the total bus capacitance stays under ~400 pF. By removing the extra pull-ups on your MCP9600 breakouts (so that you only have one 10 kohm on 3.3 V and one on 1.8 V) and keeping the four sensors wired closely (or else splitting them over two busses), the SDA line springs back to life. Alternatively you can re-engineer to a dedicated translator (PCA9306) if you need heavier pull-ups or longer runs.</span></p><div style="clear:both;"></div>