How to config the tdm port on nrf54lm20

[huma]

I want to try the tdm function on the nrf54lm20 dk.

But i have encountered problem in the first step.

I do not know how to add the tdm port and assign the pin.

Whin i enable the tdm in the device tree, there is nothin in this page.

only this code generated in the overlay files

I try to assign the pin:

But seems invalid...

Can you help me to pass the first step?

Thank you very much!

[huma]

Hello Håkon

No worries, you've already helped me a lot and thanks for that.

And thanks for your detailed explanation, which has been truly beneficial to me.

Håkon Alseth said:

However, if you switch to the 24 MHz clock source, you will be much closer to the wanted 44.1 kHz:

24000 / 44.1 = 17.007 (44.13 kHz)

I have read the page you shared to me and the datasheet of nRF54LM20A, if i change the "

mck-clock-source" to ACLK, seems it is the 24M? Do I understand correctly?

Håkon Alseth said:

The caveat at this time is that the zephyr driver does not support this clock source yet for the nRF54LM20, which I will report internally.

Or you mean that now i can not use ACLK as “mck-clock-source”？

There is still another question that confuses me, now we use I2S for TDM, does this mean that we cannot really use TDM format signals, for example, I don't think setting "i2s_cfg.channels" to a value greater than 2 is valid...

Thank you very much!

[Håkon Alseth]

Hello,

 

huma said:

I have read the page you shared to me and the datasheet of nRF54LM20A, if i change the "

mck-clock-source" to ACLK, seems it is the 24M? Do I understand correctly?

Yes, this shall change the clock source for MCK output, but I would recommend that you double-check the SCK/WS output to ensure that those are correct.

As mentioned, the driver is not fully supporting these features, it seems.

huma said:

There is still another question that confuses me, now we use I2S for TDM, does this mean that we cannot really use TDM format signals, for example, I don't think setting "i2s_cfg.channels" to a value greater than 2 is valid...

These two modes are not setting max_num_of_channels=2:

https://github.com/nrfconnect/sdk-zephyr/blob/main/drivers/i2s/i2s_nrf_tdm.c#L533-L546

 

ie. "I2S_FMT_DATA_FORMAT_PCM_SHORT" and "I2S_FMT_DATA_FORMAT_PCM_LONG".

This test sets up different modes and configurations, which could be beneficial for your use-case:

https://github.com/nrfconnect/sdk-zephyr/blob/main/tests/drivers/i2s/i2s_additional/src/main.c

 

Kind regards,

Håkon

[huma]

Hello Håkon

Thank you, i have to ask for help...

I modified your project, the wave(lrclk, bclk, data) looks good, but when i connect to a ex-codec(adau1761),  the sound is distortion(can distinguish sound, but with heavy distortion, like data misalignment). But the same voice data i played on nrf5340 audio DK is well.

And i have tried everything i can, but i can not find the problem, can you help me?

hello_world_i2s_lm20a_modified.zip

Thank you very much!

[Håkon Alseth]

Hello,

 

huma said:

I modified your project, the wave(lrclk, bclk, data) looks good, but when i connect to a ex-codec(adau1761),  the sound is distortion(can distinguish sound, but with heavy distortion, like data misalignment). But the same voice data i played on nrf5340 audio DK is well.

It hard for me to give a good indication, as I do not have the same setup as you.

How does the waveforms (logic trace) compare between the two setups? Is the working communication I2S or left/right justified?

 

Kind regards,

Håkon

[huma]

Hello Håkon

I understand, you have already help me a lot.

Thank you very much!

I will close this ticket.