I have a circuit board that is connected to a Raspberry through GPIO. When I was exchanging the Rasp for the Jetson Nano, I failed to notice that PIN27 (I2C-SDA) is not a GPIO in the Jetson Nano. That pin was being fed a 3.3V signal constantly by the circuit board and when booting up the jetson nano, it failed to do so.
Disconnecting the PIN solved the issue.
This is not a problem as we can simply change PINs but given that the fact that I2C is pulled up to 3.3V by default, why is a 3.3V signal in that PIN stopping the board from booting?
hello diogoremiao,
did you mean you input 3.3V to pin-27 of [J41] 40-pin expansion header?
may I know why you’re doing this. thanks
Hey Jerry.
Yes that is exactly that. I did not do it on purpose, I only later on noticed that that output that was connected to pin-27 was always on at 3.3V. After that, I disabled it and everything boot correctly. My question is why did the board not boot in that condition, given that pin-27 is itself at 3.3V by default. Is it the normal and expected behaviour?
The power on sequence should be followed, the 3.3V of I2C should follow that too. So the external 3.3V to the pin might cause system status abnormal if not follow the power on sequence.