Full Version: Second i2c bus not recognised
You're currently viewing a stripped down version of our content. View the full version with proper formatting.
Recently been playing with a bme280. Have had it running on a pi zero using node-red. Today I connected it to my 3b+ running openplotter. I’ve set up a second i2c bus (4) for the bme 280. The nod-red bme280 node is initialised on this bus and runs ok. Maybe Im missing something simple but I cannot get the openplotter i2c app to recognise the second bus, am I missing something? If I connect the bme280 in parallel with my imu, on the first bus, it is recognised by the i2c app.
Question to your question ? Why a 2nd I2C bus. I'm putting together lots of sensors and wonder if I should have 2 busses. Thinking about it . .

- The speed of an I2C should be enough to handle lots of devices.
- Additional devices probably means more wire and capacitance, but that could be addressed by a booster chip.
- 2 buses means a short will only bring down the devices on that bus.

Any thoughts ?
Ease of wiring really, no issues with speed. I don’t then need to parallel my bce280 and imu onto the std bus1. You can configure at least at least 3 i2c buses. Be careful when you make connections, that you connect the +ve on the device to 3.3 or 5 volt pins on the board. Easy make a mistake and have on occasions got the sda  and scl the wrong way round but no damage then. I have learnt from exeperience bricking rpi4 powering off the gpio pins and not checking the connections before powering up.