nRF54LM20B I2S DAC (MAX98357A) support – feasibility, sample application, and overlay file

[Subhiksha]

Hello Nordic Team,

We are trying to test an I2S DAC (MAX98357A) with the nRF54LM20B EVK. Could you confirm if this is supported and which sample application is recommended for a simple I2S audio test?

Also, we tried the audio_codec sample (NCS v3.3.0), but it does not include a board overlay for nRF54LM20B—could you please share a reference overlay or confirm support?

Regards,

Subhiksha

[Subhiksha]

Hi Maria,

Thank you for your response.

May I know which sample application you have taken and built it?

Here I'm attaching the overlay file which i have been using.

/ {
	aliases {
		i2s-node0 = &tdm;
	};
};

&pinctrl {
	tdm_default_alt: tdm_default_alt {
		group1 {
			psels = <NRF_PSEL(TDM_SCK_M, 1,10)>,
				    <NRF_PSEL(TDM_FSYNC_M, 0, 7)>,
				    <NRF_PSEL(TDM_SDOUT, 1, 12)>;  /* TDM_SDOUT shorted to TDM_SDIN */
		};
	};
};

&tdm {
	status = "okay";
	pinctrl-0 = <&tdm_default_alt>;
	pinctrl-names = "default";
};

Regards,

Subhiksha

[Maria Gilje]

Hi Subhiksha,

I used zephyr/samples/drivers/i2s/i2s_codec. I can see now that you wrote audio_codec, which I assume is the zephyr/samples/drivers/audio/codec sample. My apologies for the confusion. 

I am not able to reproduce the errors you showed in your screenshot with the audio/codec sample. Are you building another sample here? Or are you building your own application? 

Also, I note that your build target is the nrf54lm20dk/nrf54lm20/cpuapp/ns. Make sure that you have an .overlay for the build target you are using. 

Just to let you know, I will be away until Tuesday, but I'll follow up when I get back. 

Best regards,

Maria

[Subhiksha]

Hello Maria,

Thank you for your clarification.

We have tried building both samples:

• zephyr/samples/drivers/i2s/i2s_codec
• zephyr/samples/drivers/audio/codec

However, in both cases, we are still encountering build errors similar to the one shared earlier.

Additionally, we noticed that there is no default board-specific overlay file available for nrf54lm20dk/nrf54lm20/cpuapp/ns in these samples. So we created a custom overlay by referring to the nrf54lm20dk_nrf54lm20_common.dtsi file, but the issue persists.

We wanted to clarify:

• Did you use a default overlay (if available) for nRF54LM20B while testing?
• Or did you create a custom overlay manually for your setup?

If possible, could you please share a reference overlay or configuration that worked in your setup?

Please let us know if you need our overlay file or build logs—we can share them for further debugging.

Regards,
Subhiksha

[Maria Gilje]

Subhiksha said:

We wanted to clarify:

• Did you use a default overlay (if available) for nRF54LM20B while testing?
• Or did you create a custom overlay manually for your setup?

I created a custom overlay which I shared in this reply: 

Maria Gilje said:

I was able to successfully build the sample for nRF54LM20B with this .overlay, main.c, Kconfig, and .conf fragment: 

nrf54lm20dk_nrf54lm20b_cpuapp_ns.overlay

The _ns.overlay will only be used when building for the /ns target, and overlays without "_ns" will not be used when building for the /ns target. 

Subhiksha said:

Please let us know if you need our overlay file or build logs—we can share them for further debugging.

Yes, please share the full build logs (with Insert->Code) so I can analyse the full output you get. 

Best regards,

Maria