PCM5122EVM-U: Trying to use the PCM5122EVM-U's I2C on the LattePanda with Linux

It could be a driver issue. How do I get these drivers to work on my Linux?

Hi Mir

I am not the right person for Linux driver issues. can you help with this Linux driver issue or should it go to Shenghao?

Regards,

Arash

Going to Shenghao would be great! Thanks!

Hi,

This sounds like a hardware issue and not a software issue to me. Can you check how your W1 and W2 headers are configured on your EVM?

It looks like the MC line is generated by the TAS1020, but if you are connected to your Linux computer, you can connect to the clock generated by the computer. Make sure your W1 and W2 are connected so your test points are SCL and SDA. Are you able to see any clock or data on these test points on a scope? 

Best,
Mir

I checked and I think the driver snd-soc-pcm512x-i2c.ko is the correct driver and I have it, so it could be a hardware issue. Maybe I have something wrong here. Could you check it out for me? Thanks 

And this is the site for the LattePanda layout... docs.lattepanda.com/.../

Hi,

Can you also try running "sudo i2cdetect -y 1"? The -r may not be right for an EVM. I recently ran into this issue with another board so maybe you can try that. And check all the pages of I2C busses - you can do sudo i2cdetect -l to list all the busses with addresses in use.

Also, can you use the 1.8V and GND provided by the lattepanda board next to the SDA and SCL lines for the pullup/down?

Best,
Mir

Hello. I'm using the sudo i2c detect command for each bus but I don't have the connection on any. I tried without the -r and I still don't have it. I can't see the "40:" row with that command and it'll say "Warning: Can't use SMBus Quick Write command, will skip some addresses". I'm also now using the 1.8V and GRND for the pullup and it's still not working.

Can you attach a schematic of how your EVM connections are laid out? I am having trouble following the picture. Also, could you try plugging in your SCL and SDA wires into the test points TP3 and TP4? 

Best,
Mir

Here is the diagram. I have also tried the TP3, TP4, and the W3 wedges for the SDA and SCL but it is still not working.

Hi,

Mir is out of office and will return on Monday to follow up with you.

Thanks,
Jeff McPherson

Hi,

Ok, first let's make sure your I2C lines are pulled to what your DVDD level is - from your diagram, I am guessing your DVDD is 3.3V, so your I2C needs to be at 3.3V. Also, can you try without the pull up resistors? Maybe they are limiting the current too much with the test boards. Just connecting SCL to SCL and SDA to SDA might help. 

Are you seeing any clock when you measure with a scope on the SCL line, or any data on SDA? Let me know.

Best,
Mir

I tried without the pullup resistors and only using 3.3V but it still didnt work. I didnt see anything on the oscilloscope.

Hi,

No clock on SCL or data on SDA? This may be an issue with your MCU - you should be able to turn on I2C communication which will enable the clock, as the DAC is an I2C "slave" where it needs to be provided a clock to communicate with the MCU. If you are still having problems with no clock/data from the MCU, I would suggest asking on the LattePanda forums for help there, and then I can help more with a script or configuration for your PCM5122. 

Best,
Mir