Help With I2C on Turbot

[DuaneAugust]

I am trying to get an I2C sensor to work with my MinnowBoard Turbot (single ethernet; firmware version 0.99). I am running Debian Linux (Stretch) installed on an SD card. The sensor I am trying to use is this D-A converter:

https://www.adafruit.com/product/1083

The sensor address is 1001000 = 72 = 0x48. Clock and data lines are connected to pins 13 and 15.

Here is some relevant information:

dadamia@Minnow-1:~$ lsmod | grep i2c i2c_i801 24576 0 i2c_smbus 16384 1 i2c_i801 i2c_algo_bit 16384 2 igb,i915 i2c_designware_platform 16384 0 i2c_designware_core 20480 1 i2c_designware_platform dadamia@Minnow-1:~$

dadamia@Minnow-1:~$ ls /sys/class/i2c-adapter i2c-0 i2c-1 i2c-10 i2c-2 i2c-3 i2c-4 i2c-5 i2c-6 i2c-7 i2c-8 i2c-9 dadamia@Minnow-1:~$ ls /sys/class/i2c-adapter/i2c-0 delete_device firmware_node name power uevent device i2c-MSFT8000:00 new_device subsystem dadamia@Minnow-1:~$ ls /sys/class/i2c-adapter/i2c-1 delete_device firmware_node new_device subsystem device name power uevent dadamia@Minnow-1:~$ ls /sys/class/i2c-adapter/i2c-2 delete_device firmware_node new_device subsystem device name power uevent dadamia@Minnow-1:~$ ls /sys/class/i2c-adapter/i2c-3 delete_device device name new_device power subsystem uevent dadamia@Minnow-1:~$

(Results for i2c-4 through i2c-10 are the same as for i2c-3.)

According to the tutorial at

https://minnowboard.org/tutorials/connecting-device-sensor-low-speed-expansion-lse-header

I should see a response from the "i2cdetect -r" command.

root@Minnow-1:/home/dadamia# i2cdetect -r 0 Error: Could not open file /dev/i2c-0' or/dev/i2c/0': No such file or directory

Same result for numbers 1 - 10. There are no files of that sort in my /dev directory. How are these files created?

What am I missing here?

[naikrovek]

those are virtual files (they don't actually exist on disk) and only show up when the proper kernel drivers are loaded. it looks like you have at least some i2c modules loaded, though.

this is just a small bit of info for you -- I don't know how to fix that myself, aside from compiling a custom kernel with the required drivers included. there may be a way to turn on those devices either in the BIOS or via configuration in Linux.

[DuaneAugust]

It looks like I need a kernel module called i2c-bcm2708, which is not in the Debian repository. There are about a million articles on the Internet explaining how to install this on a Raspberry Pi, but I can't find a version for Debian Linux on a MinnowBoard.

The source code is on GigHub here (second item):

https://github.com/bootc/linux/tree/8002705053f49235f3b530f3a998aa75dd1f33a7/drivers/i2c

I'm new to GitHub. Do I just download the whole directory and run the makefile? Does anyone have a pre-compiled i2c-bcm2708 for Debian Linux?

[naikrovek]

That's the module you would use if you were using a raspberry pi. So that's not what you need.

I don't know exactly what you need, but that's isn't it.

[DuaneAugust]

You are right. For Debian I needed to do the following.

1. Install packages libi2c-dev and i2c-tools. Both are in the normal Debian repository.

2. Install the i2c-dev driver by running (as root) "modprobe i2c-dev". This created i2c-0 through i2c-10 in /dev.

After doing that, the "i2cdetect -r 0" command ran and found my i2c device.

I have a lot more work to do to get my device to work, but at least I am through the first 3 steps of the tutorial at

https://minnowboard.org/tutorials/connecting-device-sensor-low-speed-expansion-lse-header