Activating I2C1 in BBB Rev C

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1

Hi all,

I would like to use both I2C1 and I2C2 which are available in Beaglebone Black P9 connector. I could make I2C2 working. But so far I couldn’t make I2C1 working.

In /boot/uEnv.txt, I have not commented the line
cmdline=coherent_pool=1M net.ifnames=0 quiet cape_universal=enable

That means Universal cap is active.

So I cannot use the command

echo BB-I2C1 > /sys/devices/platform/bone_capemgr/slots

for enabling I2C1.

I would like to make Universal Cape enabled, other wise I will not be able to make the P9_14 and P9_16 as PWMs.

So my question is, is there anyway to enable I2C1, while Universal Cap is enabled?

I am using the latest debian image - bone-debian-8.7-lxqt-4gb-armhf-2017-03-19-4gb.img and BBB Rev C.

I have examined the am335x-boneblack.dts file (got from coverting /boot/dtbs/4.4.54-ti-r93/am335x-boneblack.dtb).

In this .dts file i2c1 portion is as shown below.

i2c@4802a000 {
compatible = “ti,omap4-i2c”;
#address-cells = <0x1>;
#size-cells = <0x0>;
ti,hwmods = “i2c2”;
reg = <0x4802a000 0x1000>;
interrupts = <0x47>;
status = “disabled”;
linux,phandle = <0xa0>;
phandle = <0xa0>;
};

pinmux_i2c2_pins {
pinctrl-single,pins = <0x178 0x33 0x17c 0x33>;
linux,phandle = <0x35>;
phandle = <0x35>;
};

I modified it as below.

i2c@4802a000 {
compatible = “ti,omap4-i2c”;
#address-cells = <0x1>;
#size-cells = <0x0>;
ti,hwmods = “i2c2”;
reg = <0x4802a000 0x1000>;
interrupts = <0x47>;
status = “okay”;
pinctrl-names = “default”;
pinctrl-0 = <0x35>;
clock-frequency = <0x61a80>;
linux,phandle = <0xa0>;
phandle = <0xa0>;
};

pinmux_i2c2_pins {
pinctrl-single,pins = <0x178 0x33 0x17c 0x33>;
linux,phandle = <0x35>;
phandle = <0x35>;
};

But still I2C1 is not working. Is my procedure right? Am I missing something?

Expecting Your fast reply.

Thanks in advance for the help.

Thanks & Regards,
Sajeevan.K

2

What I do is enable them using config-pin like so (pins p9-17 & p9-18 in the example):
sudo config-pin p9-17 i2c sudo config-pin p9-18 i2c
by default those are configured as gpio. This settings are lost when you restart, but you can autoexecute those commands every boot.

You can see how are configured (or check if the previos command worked) with the -q option:

config-pin -q p9-17

list available modes with -l:

config-pin -l p9-17

or get detailed info with -i:

config-pin -i p9-17

That’s what i am using for the moment, but I like to also know for a more correct/goodpractice/efficient/permanent/lowlevel/before-boot/devicetree/uboot way of setting those parameters.

Other thing: the latest images were updated check https://beagleboard.org/latest-images.
Also there are monthly and weekly releases: https://rcn-ee.net
You most probably need to update u-boot to go from bone-debian-8.7-lxqt-4gb-armhf-2017-03-19-4gb.img to the latest.

Regards,

3

overlays are the best permanent solution

4

Hi Jose Valenzuela San Juan,

Thank You very much.
Your suggestion solved my issue.

Earlier I tried something like this as per the following video for pwm enabling - https://www.youtube.com/watch?v=MT3wjlzQhNQ.

I tried

config-pin P9.17 i2c

config-pin P9.18 i2c

But that was not successful.

Now I got the correct solution

config-pin p9-17 i2c

config-pin p9-18 i2c

from You. Thank You.
If You provide some documents which describes this, that would be more appreciated.

Thanks & Regards,
Sajeevan.K

5

Good to know that the info was helpful.

That’s weird, the script is made so that its friendly with how you input the pin name: 917, p917, 9.17, 9-17, p9.17, P9-17 and so on, all work fine…

The documentation is in the github page of the universal device tree overlay and supporting scripts:
https://github.com/cdsteinkuehler/beaglebone-universal-io

regards,

6

I forgot to mention
I had the image version that you are using and after an apt-upgrade (from debian image - bone-debian-8.7-lxqt-4gb-armhf-2017-03-19-4gb.img and BBB Rev C. in july) config-pin stopped working.

https://groups.google.com/d/msg/beagleboard/AvRrv9aaFbw/Gfl-384BCAAJ

Flashing the latest images solved the problem.

One more thing. If you update to newer images, the way the overlays are loaded changed, so that video is now outdated.

https://forum.digikey.com/t/all-beaglebone-varients-u-boot-overlays/26
https://groups.google.com/d/msg/beagleboard/W0QPDee5u2s/Fl_LeVnmEgAJ

Regards,

7

Config-pin works fine though

8

Hi Jose Valenzuela San Juan,

Thank You very much for the information.

Based on Your mail, I tested again with

config-pin P9.17 i2c

config-pin P9.18 i2c

Now it is working.

I might not have tested it properly.

or I might have tested it, before doing modification in .dts file.

Thank You very much for giving me plenty of information.

Thanks & Regards,
Sajeevan.K

Thank

9

Hello,

Look here if you are wanting it to last past boot: https://github.com/adafruit/adafruit-beaglebone-io-python/blob/master/doc/run_config-pin_during_startup.md.

Enjoy,

Seth

P.S. This helped me keep my configuration after boot, i.e. after reboot or starting the machine.