phobos79
Posts: 2
Joined: Thu Apr 08, 2021 11:58 am

Re: I2C slave on Raspberry Pi 4 Model B?

Fri Apr 09, 2021 9:28 am

An update, to i think is the "final" way to have pi4 b as i2c slave only,

kernel i2c support (raspi-config) is needed only for test with i2cdetect, and can be disabled without losing slave functionality, pigpio only will take care of slave

but must keep all 4 wires in, detaching "master" gpio will stop arduino trasmitting around one minute later (i use a logic level shifter)

durapensa
Posts: 12
Joined: Mon Oct 19, 2020 6:44 pm

Re: I2C slave on Raspberry Pi 4 Model B?

Wed Apr 21, 2021 9:22 pm

phobos79 wrote:
Thu Apr 08, 2021 12:09 pm

2) connect wires to i2c bus, the standard pin 3 and 5 for the main master i2c - important, the i2c slave will not work without, i don't know why
I suspect it's working this way because the RPi I2C bus on pins 3 & 5 provide 3.3V pull-ups for SDA & SCL. Did you disable the 5V pull-ups on the Arduino as described at https://forum.arduino.cc/t/i2c-pull-up- ... s/286734/7 ?

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