I'm trying to get an MCP3421 on I2C-1 working using the built-in mcp3422 driver.
The ADC shows up on addr 0x68 using i2cdetect (as the only device on that bus).
The only thing that seems to do anything successful is "sudo modprobe mcp3422" which creates "/sys/bus/iio", etc.
I can't create a new device using "sudo echo mcp3421 0x68 > /sys/class/i2c-adapter/i2c-1/new_device" (permission denied).
Are these permissions correct? "--w------- 1 root root 4096 Dec 2 15:01 /sys/class/i2c-adapter/i2c-1/new_device"
I also can't apply the Raspbian included mcp342x.dtbo using "sudo dtoverlay /boot/overlays/mcp342x.dtbo addr=0x68 mcp3421" (* Failed to apply overlay '0_mcp342x' (kernel)). udevadm monitor outputs nothing in this case, but dmesg shows:
[1553.084406] OF: overlay: find target, node: /[email protected], phandle 0xc8 not found
[ 1553.084421] OF: overlay: init_overlay_changeset() failed, ret = -22
Where the listed phandle value seems to change from time to time.
I tried on both a Pi 3B+ and 4 with the exact same results which makes me think I'm doing something wrong..
Raspbian GNU/Linux 10 (buster)
Linux raspberrypi 4.19.75-v7l+ #1270 SMP Tue Sep 24 18:51:41 BST 2019 armv7l GNU/Linux