Hello folks,
Another update about I2C. After a few weeks of smooth operation, the setup I suggested in my previous reply began to show malfunctions : the I2C bus was sometimes ineffective, with the following symptoms : MMA dead, BNO dead, and WAS dead. I didn’t spend much time debugging the circuit, but the problems may have been caused by a capacitive load too high on the bus, a burnt NMOS, crappy soldering job, etc…
To fix the problem, I decided to design the I2C link again, from scratch, but this time using an I2C bus extender, namely the P82B96 from TI. It’s designed to drive I2C on two twisted pairs, with a capacitive load up to 4 nF ! Below there are the schematic of the whole system, and a few pics.
At the moment, this setup was tested in the field and showed good results : the link with MMA and BNO is strong and uninterrupted.
I intend to use this I2C extender in the PCB I’m designing at the moment.
Overall wiring diagram
Cabin side
Roof side