I2C devices that are powered from 5V can be connected to a Pi AS LONG AS they do not have on board pull-up resistors on SCL and SDA AND they recognise 3.3V as a logic high on the i2c bus.I am working on an I2C project using the PI 5 with some sensors. One of the sensors operates at VCC 5V and I accidentally connected the SCL/SDA line from the PI to the 5V. I removed the connections and re-wired one sensor at a time to the PI.
But I cannot detect any slave devices on the bus and i2cdetect returns empty always.
The SDA and SCL GPIO Pins on the PI reads about 6V upon bootup with nothing connected.
What should the voltage on these pins be at bootup?
Did I damage those GPIO Pins on the PI?
If you read 6V on the i2C GPIO pins when nothing is connected to them you are reading them incorrectly. Possibly a flat battery in your meter. There is no way they can read higher than 3.3V on a Pi with nothing connected to them.
You should see either 3.3V on the pins when idling, and pulses to 0V when busy.
A quick test of the i2c bus is to disconnect everything, disable any sensor dtoverlays, but leave the i2c one there.
Then run i2cdetect -y 1, which should show nothing found.
Connect SDA (pin 3) to ground and run the i2cdetect again. This time it should show ALL addresses found.
Finally disconnect SDA and connect SCL (pin 5) to ground and run i2cdetect again. This time it should be very slow and detect nothing.
If you get any other results the i2c port is broken. Damage to one set of pins can cause overheating inside the chip, slowly burning out all other pins until the chip overheats and dies.
Statistics: Posted by rpdom — Sun Aug 18, 2024 9:49 am