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This is the price I pay for being greedy,

While working through the book exploring raspberry pi by Derek Malloy (an excellent book for understanding embedded Linux),

When I append

bcm2835.vc_i2c_override=1 to /boot/cmdline.txt using

sudo sh -c "echo bcm2835.vc_i2c_override=1 > /boot/cmdline.txt"

and append

dtparam=i2c_vc=on to /boot/config.txt using 

sudo sh -c "echo dtparam=i2c_vc=on > /boot/config.txt"

my RPI3 crashes upon reboot, meaning it goes into panic mode and none of the cores load.

reinstalling raspbian lite from debug fixes the problem short of being able to enable i2c-0, the i2c device used for RPI HATs.

uname -a tells me that I'm using 4.9.59-v7, I later tried this on 4.14.18-v7 resulting in the same behavior.

the i2c-1 device was/is available in /dev, I manually enabled this prior to attempting to enable i2c-0.

/boot/config.txt has dtparam=i2c_vc=on and dtparam=i2c_arm=on

/etc/modules contained i2c-dev and i2c-bcm2835

Any help or suggestions would be greatly appreciated.

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2 Answers 2

Reset to default
1

I2C bus 0 is not available for use on the Pi3B. It is used internally.

See https://www.raspberrypi.org/forums/viewtopic.php?f=44&t=138897&p=923243

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I was had luck enabling the 3rd & 4th i2c buses by adding the following in my /boot/config.txt (assumes i2c is enabled in raspi-config:

dtoverlay=i2c-gpio,bus=4,i2c_gpio_delay_us=1,i2c_gpio_sda=23,i2c_gpio_scl=24
dtoverlay=i2c-gpio,bus=3,i2c_gpio_delay_us=1,i2c_gpio_sda=17,i2c_gpio_scl=27

I did this to test that it would work first:

$ dtoverlay i2c-gpio bus=4 i2c_gpio_delay_us=1 i2c_gpio_sda=23 i2c_gpio_scl=24
$ tail /var/log/messages
...
Oct 18 06:25:12 test1 kernel: [  314.858994] i2c-gpio 4.i2c: using lines 23 (SDA) and 24 (SCL)
$ i2cdetect -l
i2c-1   i2c             bcm2835 (i2c@7e804000)                  I2C adapter
i2c-4   i2c             4.i2c                                   I2C adapter
$ i2cdetect -y 4
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- --
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- --
20: -- -- -- -- -- -- -- --
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  • 1
    This Answer is totally irrelevant - it only applies to the Pi4; which wasn't available when the Question was asked and i2c-0 STILL is unavailable on the Pi4.
    – Milliways
    Oct 18, 2020 at 5:53

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