Hi,
Just some feedback if you happen to stumble across this topic in desperation. So my analysis is that there must be a bug with the Onion 2 I2C implementation. With that said @t-gabor had a thread that described how he managed to overcome some of the i2c limitations by moving to a "bit-banged" i2c approach.
For those interested the following method was used on a Omega Onion 2+ (firmware v0.1.10-b160):
- Install the relevant kernal modules (Thanks @t-gabor for compiling):
- kmod-i2c-gpio-custom_4.4.46-2_mipsel_24kc.ipk
- kmod-i2c-gpio_4.4.46-1_mipsel_24kc.ipk
- kmod-i2c-algo-bit_4.4.46-1_mipsel_24kc.ipk
This is done by downloading the above packages locally and running them in:
opkg install --force-depends kmod-i2c-algo-bit_4.4.46-1_mipsel_24kc.ipk
opkg install --force-depends kmod-i2c-gpio_4.4.46-1_mipsel_24kc.ipk
opkg install --force-depends kmod-i2c-gpio-custom_4.4.46-2_mipsel_24kc.ipk
the --force-depends is required as the onion thinks the kernel is at a too low version. if you are interested you can run:
root@Omega-XXXX:~# opkg list-installed | grep kernel
kernel - 4.4.46-1-611bddde2031bc44b7d050f62495d772
In order to get the current kernel version, which you will find the last section of numbers are lower that the expected value for the compiled packages above.
Anyhow what confused me for a good few hours was that the opkg install will show errors at the end even though it was successful (i.e. notice the "Installing" and "Configuring" sections):
root@Omega-XXXX:~/ipk# opkg install --force-depends kmod-i2c-algo-bit_4.4.46-1_mipsel_24kc.ipk
Installing kmod-i2c-algo-bit (4.4.46-1) to root...
Configuring kmod-i2c-algo-bit.
Collected errors:
* satisfy_dependencies_for: Cannot satisfy the following dependencies for kmod-i2c-algo-bit:
* kernel (= 4.4.46-1-d0a487fc7d1c9f083b7de0fb8c2a7c07) *
Once these modules are installed we need to load them using the following commands:
omega2-ctrl gpiomux set i2c gpio
insmod i2c-algo-bit
insmod i2c-gpio
insmod i2c-gpio-custom bus0=1,5,4
with that you can now try the newly created /dev/i2c-1 device:
i2cdetect -y 1
And vola:
root@Omega-XXXX:~# i2cdetect -y 1
0 1 2 3 4 5 6 7 8 9 a b c d e f
00: -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: 20 -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
60: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
70: -- -- -- -- -- -- -- --
Anyhow to wrap things up you can do this setup automatically at bootup with the following init.d script. create using vi in /etc/init.d/I2Cbb
#!/bin/sh /etc/rc.common
# Creates bit-banged i2c-device /dev/i2c-1 on pins 5,4.
# NOTE: This hides /dev/i2c-0!
START=98
STOP=97
start() {
omega2-ctrl gpiomux set i2c gpio
insmod i2c-algo-bit
insmod i2c-gpio
insmod i2c-gpio-custom bus0=1,5,4
}
stop() {
rmmod i2c-gpio-custom
rmmod i2c-gpio
rmmod i2c-algo-bit
omega2-ctrl gpiomux set i2c i2c
}
restart()
{
stop
start
}
And another hour or so of frustration and rebooting reminded me again of missing the basics, do not forget to enable and make executable the script!
chmod 755 /etc/init.d/I2Cbb
/etc/init.d/I2Cbb enable
*** EDIT ***
On an final note, using bitbanged I2C allows you to set the Onion I2C bus clock speed (SCL). To do this add the extra parameter to the the init.d script
insmod i2c-gpio-custom bus0=1,5,4,x
where x is is number based on the following formula:
I2C speed (kHz) = 500 / x
Cheers,
UFD
