I have a Raspberry Pi 4 B and I'm trying to set up in I2C Connection with an MCP23018-E/SP I/O-Port-Expander via GPIO02 and GPIO03. I have enabled I2c on the Raspi by:
adding: dtparam=i2c1=on to /boot/config.txt
dtparam=i2s=on to /boot/config.txt dtparam=i2c_arm=on to /boot/config.txt dtoverlay=i2c1,pin2_3(tried it as well without the last three)
added all modules in /etc/modules
enabled automatic load of i2c kernel at boot
installed i2c-tools, python-smbus.
$ ls -l /dev/i2c-*
crw-rw--- 1 root i2c 89, 0 Okt 05 18:00 /dev/i2c-1
So my bus should be set up correctly. I know, you have to use the alternative functions for the GPIO Pins to get I2C, so I set:
- raspi-gpio set 02 a0
- raspi-gpio set 03 a0 (because SDA1/SCL1 are Alternate functions for GPIO 02 and GPIO 03. I get as well for raspi-gpio get 02,03 that the SDA/SCL are enabled.
I tried it aswell for different Pins, whose alternate function can provide an i2c buses, but none of them show a result for i2cdetect -y 1
I looked at the channels with an oscilloscope, and from my point of view, the Raspi is NOT sending SDA and SCL, there are both just high at 3,3 V.
I really tried everything to send the I2C signals, but it will not work and I don't have a different device to check my circuit, but I'm pretty sure on the hardware side everything is correctly wired.
Any help would be really helpful.