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!

[Håkon Alseth]

Hi,

 

The TDM can be sourced via two clocks, as shown here:

https://docs.nordicsemi.com/bundle/ps_nrf54LM20A/page/tdm.html#d1594e1438

 

44100 Hz is not exactly possible with these two clock sources, so you will have a bit of a miss, but 210 Hz off is a bit much.

I see that the example that I sent you is missing a crucial component, and that is starting the HFXO.

 

Could you try adding this function (and calling it) on boot?

https://github.com/nrfconnect/sdk-nrf/blob/main/samples/peripheral/radio_test/src/main.c#L28-L70

 

Similar to this (headers and all added for you):

/*
 * Copyright (c) 2012-2014 Wind River Systems, Inc.
 *
 * SPDX-License-Identifier: Apache-2.0
 */

#include <zephyr/kernel.h>
#include <zephyr/device.h>
#include <zephyr/drivers/i2s.h>
#include <zephyr/sys/iterable_sections.h>
#include <zephyr/drivers/clock_control.h>
#include <zephyr/drivers/clock_control/nrf_clock_control.h>
#if NRF54L_ERRATA_20_PRESENT
#include <hal/nrf_power.h>
#endif /* NRF54L_ERRATA_20_PRESENT */

#include <zephyr/logging/log.h>

#define LOG_MODULE_NAME i2s_test
LOG_MODULE_REGISTER(LOG_MODULE_NAME);

#define SAMPLE_NO 64
#define NUM_BLOCKS 4
#define BLOCK_SIZE (SAMPLE_NO * sizeof(int16_t))

K_MEM_SLAB_DEFINE(tx_mem_slab, BLOCK_SIZE, NUM_BLOCKS, 4);

const struct device *const i2s_dev = DEVICE_DT_GET(DT_ALIAS(i2s_node0));

/* Audio samples*/
static int16_t data[SAMPLE_NO];

static void clock_init(void)
{
	int err;
	int res;
	struct onoff_manager *clk_mgr;
	struct onoff_client clk_cli;

	clk_mgr = z_nrf_clock_control_get_onoff(CLOCK_CONTROL_NRF_SUBSYS_HF);
	if (!clk_mgr) {
		printk("Unable to get the Clock manager\n");
		return;
	}

	sys_notify_init_spinwait(&clk_cli.notify);

	err = onoff_request(clk_mgr, &clk_cli);
	if (err < 0) {
		printk("Clock request failed: %d\n", err);
		return;
	}

	do {
		err = sys_notify_fetch_result(&clk_cli.notify, &res);
		if (!err && res) {
			printk("Clock could not be started: %d\n", res);
			return;
		}
	} while (err);

#if NRF54L_ERRATA_20_PRESENT
	if (nrf54l_errata_20()) {
		nrf_power_task_trigger(NRF_POWER, NRF_POWER_TASK_CONSTLAT);
	}
#endif /* NRF54L_ERRATA_20_PRESENT */

#if defined(NRF54LM20A_ENGA_XXAA)
	/* MLTPAN-39 */
	nrf_clock_task_trigger(NRF_CLOCK, NRF_CLOCK_TASK_PLLSTART);
#endif /* defined(NRF54LM20A_ENGA_XXAA) */

	printk("Clock has started\n");
}

static int configure_stream(const struct device *dev_i2s, uint32_t frame_clk_freq)
{
	int err;
	struct i2s_config i2s_cfg;

	i2s_cfg.word_size = 16U;
	i2s_cfg.channels = 1U;
	i2s_cfg.format = I2S_FMT_DATA_FORMAT_I2S;
	i2s_cfg.frame_clk_freq = frame_clk_freq;
	i2s_cfg.block_size = BLOCK_SIZE;
	i2s_cfg.timeout = 1000;
	i2s_cfg.options = I2S_OPT_FRAME_CLK_SLAVE | I2S_OPT_BIT_CLK_SLAVE;

	i2s_cfg.mem_slab = &tx_mem_slab;
	err = i2s_configure(dev_i2s, I2S_DIR_TX, &i2s_cfg);
	if (err < 0) {
		LOG_ERR("Failed to configure I2S TX stream (%d)\n",
			 err);
		return err;
	}

	return 0;
}

static void fill_buf(int16_t *tx_block)
{
	memcpy(tx_block, data, sizeof(data));
}

int main(void)
{
	int err;
	int tx_idx;
	void *tx_block[NUM_BLOCKS];
	clock_init();
	LOG_INF("I2S Sample started");
	/* Fill with a fixed reckognizable pattern to make
	   any gaps apparent */
	memset(data, 0xAA, sizeof(data));

    if (!device_is_ready(i2s_dev)) {
		LOG_ERR("Device %s is not ready.", i2s_dev->name);
		return -EIO;
	}

	err = configure_stream(i2s_dev, 44100);
	if(err) {
		LOG_ERR("configure_stream() failed. (err %d)", err);
	}

	/* Prepare TX data blocks */
	for (tx_idx = 0; tx_idx < NUM_BLOCKS; tx_idx++) {
		err = k_mem_slab_alloc(&tx_mem_slab, &tx_block[tx_idx],
				       K_FOREVER);
		if(err) {
			LOG_ERR("k_mem_slab_alloc() failed. (err %d)", err);
		}
		fill_buf(tx_block[tx_idx]);
	}

	tx_idx = 0;

	/* Prefill TX queue */
	err = i2s_write(i2s_dev, tx_block[tx_idx++], BLOCK_SIZE);
	if(err) {
		LOG_ERR("i2s write() failed. (err %d)", err);
	}

	err = i2s_write(i2s_dev, tx_block[tx_idx++], BLOCK_SIZE);
	if(err) {
		LOG_ERR("i2s write() failed. (err %d)", err);
	}

	i2s_trigger(i2s_dev, I2S_DIR_TX, I2S_TRIGGER_START);

	/* Keep alternating between the two buffers */
	for(;;) {
		
		tx_idx = tx_idx & (NUM_BLOCKS-1);	
		err = i2s_write(i2s_dev, tx_block[tx_idx], BLOCK_SIZE);
		if(err) {
			LOG_ERR("i2s write() failed. (err %d)", err);
			return 1;
		}

		err = k_mem_slab_alloc(&tx_mem_slab, &tx_block[tx_idx],
				       K_FOREVER);
		if(err) {
			LOG_ERR("k_mem_slab_alloc() failed. (err %d)", err);
		}
		fill_buf(tx_block[tx_idx]);
		tx_idx++;
	}

	return 0;
}

 

Kind regards,

Håkon

[huma]

Hello Håkon

Thank you for your help.

I followed your advice and tried your code, add the clock_init.

But seem that the clock is worse...

44.1K

48K

Do you have any suggestions for this?

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.