BeagleBone Blue cannot detect i2c devices

William_Vining · June 10, 2018, 3:58am

Hello,

I am trying to connect i2c devices to my beablebone blue, but they are not detected. I have tried four different devices, but none of them appear in the output from `i2cdetect -y -r 1’ Does anybody have any advice for things I can check to get this working?

Does the i2c connection on the board include pull-up resistors for sda/scl?

Thanks,
Will

honggang_wang · June 10, 2018, 8:07pm

Hi,

I have the same problem. hope somebody can help us out.

Best.

Honggang Wang.

在 2018年6月9日星期六 UTC-4下午11:58:19，William Vining写道：

Graham1 · June 11, 2018, 1:06am

I don’t have a BeagleBone Blue, but I would assume that the necessary pull up resistors for the I2C bus to function are NOT included on the Beaglebone board.
You need to supply them externally.

— Graham

William_Vining · June 12, 2018, 3:42pm

Okay, thanks for that info. I have tried with and without pull-ups, but no luck, so I don’t think that is the problem.

Will

Graham1 · June 12, 2018, 7:18pm

Did you try
i2cdetect -y -r 2

Is the I2C device powered by 3.3 Volts?

— Graham

William_Vining · June 13, 2018, 1:35pm

Graham,

The I2C device is powered by 3.3V, and I have verified that power is going to it (there is a 3.3V out pin sou you can chain devices together and that shows 3.3V when I measure it with a multi-meter).

i2cdetect -y -r 2 and 0 both show devices, but they are not the ones I am looking for (and are present when my external devices are disconnected).

Will

Graham1 · June 13, 2018, 2:47pm

I looked at the BB Blue Schematic, and there are 4.7K pull up resistors on the I2C-1 bus, which is the one pinned out to the external I2C connector.

So, your possibilities are that your part is wired wrong, the part is bad, or the device tree you are using is not set up right for I2C-1.

What do you see when you put an oscilloscope on SDA and SCL lines?

You can usually tell the difference between them with a scope, since SCL has consistent bursts of eight transistions, and the SDA is more random.

Do you have a known good I2C device of any kind that you can hook to the I2C-1 bus for testing.

— Graham

Johan_Lind · June 27, 2018, 7:11am

Have you enabled channel 1? By default only channel 0 and 2 are enabled.

Adding the line
uboot_overlay_addr4=/lib/firmware/BB-I2C1-00A0.dtbo
in /boot/uEnv.txt should do it (if you use a recent Debian that is).

honggang_wang · June 27, 2018, 2:49pm

Thank you Johan, you are right. After enabling channel 1, i2cdetect can now find my defice.

Best.

Honggang Wang.

William_Vining · June 29, 2018, 4:34pm

This doesn’t seem to have worked for me, did you do anything else to get it working, Honggang?

Thanks,
Will

RobertCNelson · June 29, 2018, 4:41pm

What does this script show:

sudo /opt/scripts/tools/version.sh

Regards,

William_Vining · June 29, 2018, 4:44pm

Hi, I made a really stupid mistake. After taking a step back to go through everything from the beginning I discovered I had connected my I2C devices to the CAN port and not the I2C port facepalm. With the device connected properly, I do not need the line in uEnv.txt to enable the bus, it appears to be enabled by default in the image I downloaded from the beablebone website a few weeks ago.

Thanks for everyone’s thoughtful help,
Will

gtirth · September 4, 2024, 10:15pm

Hello,

I have tried everything to troubleshoot I2C problems on beaglebone blue running debian 10 and 11 but nothing works.

The problem that I am having is I am trying to run neopixel driver by adafruit and joy featherwing but none of the devices are being detected.

Can someone please help?

Thanks

foxsquirrel · September 5, 2024, 12:05pm

I don’t have bb blue, however, when you connect the board are you able to see it using i2cdetect? That is a starting point. Also make sure you have the correct overlay installed if the i2c port you are using is not on by default.

gtirth · September 5, 2024, 3:28pm

I can’t detect any peripheral I2C device that I connect to I2C port on BB blue. I already have I2C bus up and running as when I do ls /dev/i2c* it gives me 3 buses. Do i still need to add any add on modules?

foxsquirrel · September 5, 2024, 6:43pm

@sudo i2cdetect -r -y <bus number>

i2cdetect -r -y 1

Post that from all the buses.

Do you now the hex address for the device you are using, if not try to find it.

gtirth · September 5, 2024, 7:33pm

Hello,

Here is the output from all buses.

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

debian@beaglebone:~$ sudo i2cdetect -y -r 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: -- -- -- -- -- -- -- --

debian@beaglebone:~$ sudo i2cdetect -y -r 2
     0  1  2  3  4  5  6  7  8  9  a  b  c  d  e  f
00:          -- -- -- -- -- -- -- -- -- -- -- -- -- 
10: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
20: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
30: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
40: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
50: -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- -- 
60: -- -- -- -- -- -- -- -- 68 -- -- -- -- -- -- -- 
70: -- -- -- -- -- -- 76 --

debian@beaglebone:~$ uname -a
Linux beaglebone 4.19.94-ti-r42 #1buster SMP PREEMPT Tue Mar 31 19:38:29 UTC 2020 armv7l GNU/Linux

gtirth · September 5, 2024, 7:33pm

The hex address is 0x49 for featherwing joy and 0x60 for neopixel led driver

foxsquirrel · September 6, 2024, 1:42am

You should see those values show up, I don’t see them.

Make sure your device is wired correctly.
2.Correct pins?
3.Look on the schematic for a CS (chip select) that will have to be pulled high for the device to work(may or may not use it).
Reverse the SDA and SCL
Do you need pull up resistors on the SoC, some have pull ups on the board others do not. If you do be careful about the bus voltage and use a 4.7k or so resistor to pull up each line.
Go back and probe each module until you see 49, when you get it you will be close to getting it up.

If that does not yield results then it might be an overlay issue, if that is the case some one that has the board will have to jump in and provide some guidance. Without the board it is hard to troubleshoot.

gtirth · September 6, 2024, 9:39pm

None of that helped.

And yeah that is the problem, i don’t see any of the values come up for whatever reason