How do I Enable i2c2 on Armbian 24.11.1 Bookworm Minimal

jak · December 2, 2024

Armbianmonitor:

https://paste.next.armbian.com/pugawukefu

context
------------
Hardware: BPI CM4 on BPI CM4IO board
OS: Armbian 24.11.1 Bookworm Minimal Build: https://dl.armbian.com/bananapicm4io/Bookworm_current_minimal

problem

------------

How do i enable i2c2 so i can be able to use the following pins on the BPI CM4IO board for i2c

pin 82 (GPIOX_17): (MUX UNCLAIMED) (GPIO UNCLAIMED)
pin 83 (GPIOX_18): (MUX UNCLAIMED) periphs-banks:595

Previously on the ubuntu build all i had to do is add the following line to `/boot/env.txt` , `overlays="12c2"`, as stated in this doc https://wiki.banana-pi.org/Getting_Started_with_CM4#DTB_overlay

2. Update the overlays env in vfat /boot/env.txt to enable what you want.
 # Device Tree Overlays
 #   uart1           -- Enable UART1 (uart_A, GPIO Header PIN8 & PIN10)
 #   pwm_c           -- Enable PWM_C (GPIO Header PIN7)
 #   i2c2            -- Enable i2c2 (GPIO Header PIN3 & PIN5)
 #   spi0            -- Enable SPI0 (GPIO Header PIN19 & PIN21 & PIN23 & PIN24)
 overlays="i2c2 spi0 uart1"

but on the `Armbian 24.11.1 Bookworm Minimal Build` i cant find this overlay

pi@bananapicm4io:~$ sudo ls /boot/dtb-6.6.61-current-meson64/amlogic/overlay/
README.meson-overlays					meson-g12a-radxa-zero-pwmao-a-on-gpioao-11.dtbo		   meson-i2cA.dtbo
meson-fixup.scr						meson-g12a-radxa-zero-spi-spidev.dtbo			   meson-i2cB.dtbo
meson-g12-gxl-cma-pool-896MB.dtbo			meson-g12a-radxa-zero-uart-ao-a-on-gpioao-0-gpioao-1.dtbo  meson-sm1-bananapi-m5-rtl8822cs.dtbo
meson-g12-pwm-gpiox-5-fan.dtbo				meson-g12a-radxa-zero-uart-ao-b-on-gpioao-2-gpioao-3.dtbo  meson-sm1-bananapi-uartA.dtbo
meson-g12a-radxa-zero-gpio-10-led.dtbo			meson-g12a-radxa-zero-uart-ao-b-on-gpioao-8-gpioao-9.dtbo  meson-sm1-bananapi-uartAO_B.dtbo
meson-g12a-radxa-zero-gpio-8-led.dtbo			meson-g12a-radxa-zero-uart-ee-c.dtbo			   meson-sm1-bananapi-uartA_cts_rts.dtbo
meson-g12a-radxa-zero-i2c-ao-m0-gpioao-2-gpioao-3.dtbo	meson-g12b-bananapi-cm4-pwm-gpioh-5-fan.dtbo		   meson-uartA.dtbo
meson-g12a-radxa-zero-i2c-ee-m1-gpioh-6-gpioh-7.dtbo	meson-g12b-bananapi-cm4-wifi-freq-200mhz.dtbo		   meson-uartC.dtbo
meson-g12a-radxa-zero-i2c-ee-m1-gpiox-10-gpiox-11.dtbo	meson-g12b-bananapi-m2s-rtl8822cs.dtbo			   meson-w1-gpio.dtbo
meson-g12a-radxa-zero-i2c-ee-m3-gpioa-14-gpioa-15.dtbo	meson-g12b-odroid-n2-spi.dtbo				   meson-w1AB-gpio.dtbo
meson-g12a-radxa-zero-pwm-c-on-gpiox-8.dtbo		meson-g12b-waveshare-cm4-io-base-usb.dtbo
pi@bananapicm4io:~$ cat /boot/armbianEnv.txt 
verbosity=1
console=both
overlay_prefix=meson
fdtfile=amlogic/meson-g12b-bananapi-cm4-cm4io.dtb
rootdev=UUID=e4b40e17-5d66-4b52-a45e-4a8c6cdee335
rootfstype=ext4
fdt_overlays=
overlays=i2c2 
usbstoragequirks=0x2537:0x1066:u,0x2537:0x1068:u
pi@bananapicm4io:~$

i2cdetect output on Armbian (on ubuntu image i get a reading on i2cdetect -y 1 but not on armbian)

pi@bananapicm4io:~$ sudo i2cdetect -l
i2c-0	i2c       	Meson I2C adapter               	I2C adapter
i2c-1	i2c       	Meson I2C adapter               	I2C adapter
i2c-2	i2c       	DesignWare HDMI                 	I2C adapter
pi@bananapicm4io:~$ sudo i2cdetect -y 0
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         
pi@bananapicm4io:~$ sudo i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         
pi@bananapicm4io:~$

Edited December 2, 2024 by jak
wrong pins listed

c0rnelius · December 2, 2024

Create an overlay and enable it.

/dts-v1/;
/plugin/;

/ {
	fragment@0 {
		target = <&i2c2>;

		__overlay__ {
			status = "okay";
		};
	};
};

jak · December 2, 2024

@c0rnelius thanks for the quick response
I had actually tried this before, sorry I didn't include it in my original question. I get the behavior below when i add the user-overlay.

Adding this user overlay seems to enable an i2c device but i still dont get any comms on that i2c device

root@bananapicm4io:/home/pi# sudo cat /sys/kernel/debug/pinctrl/ff634400.bus:pinctrl@40-pinctrl-meson/pinmux-pins | grep i2c
pin 22 (GPIOH_6): ffd1e000.i2c (GPIO UNCLAIMED) function i2c1 group i2c1_sda_h6
pin 23 (GPIOH_7): ffd1e000.i2c (GPIO UNCLAIMED) function i2c1 group i2c1_sck_h7
pin 63 (GPIOA_14): ffd1c000.i2c (GPIO UNCLAIMED) function i2c3 group i2c3_sda_a
pin 64 (GPIOA_15): ffd1c000.i2c (GPIO UNCLAIMED) function i2c3 group i2c3_sck_a
pin 82 (GPIOX_17): ffd1d000.i2c (GPIO UNCLAIMED) function i2c2 group i2c2_sda_x
pin 83 (GPIOX_18): ffd1d000.i2c periphs-banks:595 function i2c2 group i2c2_sck_x
root@bananapicm4io:/home/pi# i2cdetect -l
i2c-0	i2c       	Meson I2C adapter               	I2C adapter
i2c-1	i2c       	Meson I2C adapter               	I2C adapter
i2c-2	i2c       	Meson I2C adapter               	I2C adapter
i2c-3	i2c       	DesignWare HDMI                 	I2C adapter
root@bananapicm4io:/home/pi#

See

root@bananapicm4io:/home/pi# i2cdetect -y 0
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         
root@bananapicm4io:/home/pi# i2cdetect -y 1
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         
root@bananapicm4io:/home/pi# i2cdetect -y 2
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         
root@bananapicm4io:/home/pi# i2cdetect -y 3
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: 30 -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --                         
root@bananapicm4io:/home/pi#

This is the same issue i had when i tried to create my own user overlay (you can see in the armbian-monitor trace my fruitless attempts)

To prove that its not my hardware connection, here is the same command runned on an SD card running this ambian build: 2023-12-26-ubuntu-20.04-server-bpi-cm4-aarch64-sd-emmc.img.zip
https://drive.google.com/drive/folders/1ogrdn-Kx5oqIOLUhwMqqMAhxZIcDYzPs

(All i did was swap the sd card and runned the same cmd, no change in h/w connections)
Notice in the trace below its able to detect the i2c device on address

root@ubuntu:/home/pi# lsb_release -a
No LSB modules are available.
Distributor ID:	Ubuntu
Description:	Ubuntu 20.04.6 LTS
Release:	20.04
Codename:	focal
root@ubuntu:/home/pi# uname -r
4.9.241-BPI-CM4
root@ubuntu:/home/pi# i2cdetect -l
i2c-3	i2c       	Meson I2C adapter               	I2C adapter
i2c-2	i2c       	Meson I2C adapter               	I2C adapter


root@ubuntu:/home/pi# i2cdetect -y 2
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- 41 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: 70 -- -- -- -- -- -- --                         
root@ubuntu:/home/pi# tail /boot/env.txt 
# 2 - 180 degree
# 3 - 270 degree
fb_rotate=0

# Device Tree Overlays
#   uart1           -- Enable UART1 (uart_A, GPIO Header PIN8 & PIN10)
#   pwm_c           -- Enable PWM_C (GPIO Header PIN7)
#   i2c2            -- Enable i2c2 (GPIO Header PIN3 & PIN5)
#   spi0            -- Enable SPI0 (GPIO Header PIN19 & PIN21 & PIN23 & PIN24)
overlays="i2c2"
root@ubuntu:/home/pi#

jak · December 2, 2024

Any idea how can build the minimal image of an earlier "stable" kernel (that supported the use of inbuilt i2c/uart overlays).

I will look into this more when I get the time but at the moment I just want to get i2c working, the ubuntu 20.04 server image is great and works but it takes a bit longer to boot, my assumption is if I can build a minimal image of the same it would improve boot time a little.

Yes am aware of the problems that come with using an earlier kernel but at the moment I want to focus on the project functional units and abstract myself from spending an entire day trying to make i2c work.

c0rnelius · December 2, 2024

@jak Something is a-mis. I'll need to investigate and get back to you.

The working IMG you are referring to is using an old BSP kernel, which is not used here.

jak · December 3, 2024

Ok, thanks @c0rnelius

c0rnelius · December 3, 2024

@jak Try this one.

/dts-v1/;
/plugin/;

/ {
	fragment@0 {
		target = <&i2c2>;
		__overlay__ {
			status = "okay";
		};
	};

	fragment@1 {
		target = <&uart_A>;
		__overlay__ {
			status = "disabled";
		};
	};
};

Result in my case:

bananapi: ~  $ sudo i2cdetect -y 2
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:                         -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- 3c -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- -- --

jak · December 3, 2024

@c0rnelius it works

root@bananapicm4io:~# i2cdetect -y 2
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- 41 -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
70: 70 -- -- -- -- -- -- --

i dont know which device is at 0x70 but i will figure it out.

Can you explain why your overlay works?

c0rnelius · December 3, 2024

43 minutes ago, jak said:

Can you explain why your overlay works?

Both Bluetooth and i2c2 use GPIOX_17 and GPIOX_18, so we need to disable Bluetooth for those HEADER PINS to function. Basically, if you need i2c2 than you are going to lose Bluetooth support.