I2C GND Differs

RE: I2C GND Differs

danielboe — Wed, 03 Feb 2021 21:50:45 GMT

okay this makes sense. maybe the sensor is not able to get the level back to gnd but the nrf chip does. We will check this out, thanks!

RE: I2C GND Differs

ketiljo — Mon, 01 Feb 2021 13:25:57 GMT

Use larger values, 10k maybe. Smaller values will of course make it worse. Some of the devices on the bus have less drive strength than others and will cause this.

RE: I2C GND Differs

danielboe — Thu, 28 Jan 2021 15:33:23 GMT

I dont think it has to do with the pullups because also with 5K the problem exists and also there is a base line visible so the port can on some point reach GND

RE: I2C GND Differs

danielboe — Thu, 28 Jan 2021 15:10:49 GMT

Hm, I tried different Values .4.7K to 800 Ohms. If I lower the value the problem moves to the top. I will try a bit more with different values. At the moment the I2C bus is connected to many BSS138 Mosfet and is routet to different devices all with the same address. So this works fine but still I wonder why the bus looks so strange

RE: I2C GND Differs

ketiljo — Thu, 28 Jan 2021 15:02:50 GMT

What's the value of the pull up resistors? It looks like one of the devices on the bus can't pull the lines down enough. Try using larger pull up resistors.