STM32F746 cannot read level of audio input signal

[aciuf]

I would like to read the level of audio input signal to use like a vu-meter instead of use analog input.

This is my code but I read always 0dB on both channels.

void AUDIO_PLAYER_Init2()
{

/* Allocat mem for Smr */

pSmrPersistentMem = malloc(smr_persistent_mem_size); /* smr_persistent_mem_size 0x188 */

pSmrScratchMem = malloc(smr_scratch_mem_size); /* smr_scratch_mem_size 0xF04 */

if (BSP_AUDIO_IN_Init(INPUT_DEVICE_INPUT_LINE_1, 80, AUDIO_FREQUENCY_48K) != 0)

LCD_LOG_SetHeader((uint8_t *)"Audio SMR Application KO");

else

LCD_LOG_SetHeader((uint8_t *)"Audio SMR Application OK");

}

void Audio_Process2()
{

    int32_t error = SMR_ERROR_NONE;

    __HAL_RCC_CRC_CLK_ENABLE();

    CRC->CR = CRC_CR_RESET;

    error = smr_reset(pSmrPersistentMem, pSmrScratchMem);

    if (error != SMR_ERROR_NONE)

    {

        BSP_LCD_DisplayStringAt(10, 20, (uint8_t *)"--err0--", LEFT_MODE);

        return (AUDIO_ERROR_SMR);

    }

    smr_static_param.sampling_rate = 48000; /* only sampling rate supported */

    error = smr_setParam(&smr_static_param, pSmrPersistentMem);

    if (error != SMR_ERROR_NONE)

    {

       BSP_LCD_DisplayStringAt(10, 20, (uint8_t *)"--err1--", LEFT_MODE);

       return (AUDIO_ERROR_SMR);

    }

    smr_dynamic_param.enable = 1; /* SMR module enabler */

    smr_dynamic_param.averaging_time = AUDIO_CFG_SMR_AVGTIME_DEFAULT;

    smr_dynamic_param.filter_type = SMR_PREFILTER_AWEIGHTING;

    error = smr_setConfig(&smr_dynamic_param, pSmrPersistentMem);

    if (error != SMR_ERROR_NONE)

    {

        BSP_LCD_DisplayStringAt(10, 20, (uint8_t *)"--err2--", LEFT_MODE);

       return (AUDIO_ERROR_SMR);

    }

    error = smr_getConfig(&smr_dynamic_param, pSmrPersistentMem);

    if (error != SMR_ERROR_NONE)

    {

       BSP_LCD_DisplayStringAt(10, 20, (uint8_t *)"--err4--", LEFT_MODE);

       return AUDIO_ERROR_SMR;

   }

   BufferHandler.nb_bytes_per_Sample = 2; /* 16-bit */

   BufferHandler.nb_channels = 2; /* stereo */

   BufferHandler.data_ptr = PCM_Data_SMR;

   BufferHandler.buffer_size = 32/2; /* just half buffer is process (size per channel) */

   BufferHandler.mode = INTERLEAVED;

   BufferHandler.data_ptr = &BufferCtl.buff[AUDIO_OUT_BUFFER_SIZE /2];

   error = smr_process(pBufferHandler, pBufferHandler, pSmrPersistentMem);

   if (error != SMR_ERROR_NONE)

  {

     BSP_LCD_DisplayStringAt(10, 20, (uint8_t *)"--err5--", LEFT_MODE);

     return (AUDIO_ERROR_SMR);

  }

   error = smr_getConfig(&smr_dynamic_param, pSmrPersistentMem);

   if (error != SMR_ERROR_NONE)

   {

      BSP_LCD_DisplayStringAt(10, 20, (uint8_t *)"--err6--", LEFT_MODE);

      return AUDIO_ERROR_SMR;

   }

sprintf((char *)str_pwr, "Left mean power: %ld dB",(int32_t)((float)smr_dynamic_param.mean_level_left*0.25));

BSP_LCD_DisplayStringAt(CHAR(0), LINE(10), (uint8_t *)str_pwr, LEFT_MODE);

sprintf((char *)str_pwr, "Right mean power: %ld dB",(int32_t)((float)smr_dynamic_param.mean_level_right*0.25));

BSP_LCD_DisplayStringAt(CHAR(0), LINE(11), (uint8_t *)str_pwr, LEFT_MODE);

}

[Andrew Neil]

---

@aciuf wrote:

Now I see some correlation from input signal and dB print but still not correct

---

Again, what exactly does that mean??

Give some specific numbers!

Show the signal that you're applying. Show the results that you're getting. Explain why you think the results are "not correct".

[aciuf]

So, ...

no signal -31dB

1.3Vrms  ->  -2dB

0.4Vrms -> -2dB

0.144Vrms -> -2dB

5mVrms -> -5dB

[aciuf]

The problem could be on the evaluation board because the line input is a mic input, so probably I saturate the input with my signal.

I will check tomorrow if this is true.

[aciuf]

I have modified the source WM8994.c to exclude the +30dB gain on input

Now the my signal does not saturate the input but still strange output:

input
   0dB  1.349Vrms   ->   on lcd read  -1dB
 -3dB   0.97Vrms    ->   on lcd read   -7dB
-10dB   0.43Vrms    ->   on lcd read -35dB

disconnected signal on lcd read -96dB

Do I have to apply a conversion to the smr_dynamic_param value ? because in the example there is a * 0.25.

    case INPUT_DEVICE_INPUT_LINE_1 :
    	BSP_LCD_DisplayStringAt(10, 80, (uint8_t *)"--INPUT_DEVICE_INPUT_LINE_1--", 0);

      /* IN1LN_TO_IN1L, IN1LP_TO_VMID, IN1RN_TO_IN1R, IN1RP_TO_VMID */
      // 0x0011 = 00010001
      //             |   +- IN1RN_TO_IN1R
      //             +-- IN1LN_TO_IN1L
      counter += CODEC_IO_Write(DeviceAddr, 0x28, 0x0011);

      /* Disable mute on IN1L_TO_MIXINL and +30dB on IN1L PGA output */
      //counter += CODEC_IO_Write(DeviceAddr, 0x29, 0x0035);
      // 0x0035 = 00110101
      //               |||
      //               +++  0dB
      //             + +30dB
      //            + unmute IN1L
      // 0x0025 = 001000101
      //               |||
      //               +++  0dB
      //             +-- 0dB
      //            +--- unmute IN1L
      counter += CODEC_IO_Write(DeviceAddr, 0x29, 0x0025);

      /* Disable mute on IN1R_TO_MIXINL, Gain = +30dB */
      counter += CODEC_IO_Write(DeviceAddr, 0x2A, 0x0025);

[aciuf]

If I multiply by 0.25

sprintf((char *)str_pwr, "Left mean power: %ld dB",(int32_t)((float)smr_dynamic_param.mean_level_left*0.25));

I can read after power on -87dB but after applying any signal and stopping it never goes back to -87 and stops at -24 as if the read buffer remains dirty.

Last version here:

#define AUDIO_OUT_BUFFER_SIZE                      3840 /* 480 * 2 (half + half) * 2 (stereo) * 2 (bytes x sample) */
//#define AUDIO_OUT_BUFFER_SIZE                       (24 * 1024)
//#define AUDIO_IN_BUFFER_SIZE                        (10 * 2304) /* buffer size in half-word */


void  AUDIO_PLAYER_Init2()
{
	int32_t error = SMR_ERROR_NONE;

	pSmrPersistentMem = malloc(smr_persistent_mem_size); /* smr_persistent_mem_size  0x188 */
	pSmrScratchMem = malloc(smr_scratch_mem_size);       /* smr_scratch_mem_size  0xF04 */


	if (BSP_AUDIO_IN_Init(INPUT_DEVICE_INPUT_LINE_1, 80, AUDIO_FREQUENCY_48K) != 0)
		LCD_LOG_SetHeader((uint8_t *)"Audio SMR Application KO");
	else
		LCD_LOG_SetHeader((uint8_t *)"Audio SMR Application OK");

	 __HAL_RCC_CRC_CLK_ENABLE();

	CRC->CR = CRC_CR_RESET;

	error = smr_reset(pSmrPersistentMem, pSmrScratchMem);
	if (error != SMR_ERROR_NONE)
	{
	 	BSP_LCD_DisplayStringAt(10, 20, (uint8_t *)"--smr_reset--", LEFT_MODE);
	    return (AUDIO_ERROR_SMR);
	}

	smr_static_param.sampling_rate = AUDIO_FREQUENCY_48K;   /* only sampling rate supported */

	error = smr_setParam(&smr_static_param, pSmrPersistentMem);
	if (error != SMR_ERROR_NONE)
	{
	   BSP_LCD_DisplayStringAt(10, 20, (uint8_t *)"--smr_setParam--", LEFT_MODE);
	   return (AUDIO_ERROR_SMR);
	}

	smr_dynamic_param.enable = 1;                        /* SMR module enabler */
	smr_dynamic_param.averaging_time = AUDIO_CFG_SMR_AVGTIME_DEFAULT;
	smr_dynamic_param.filter_type = SMR_PREFILTER_AWEIGHTING ; // SMR_PREFILTER_NONE;

	error = smr_setConfig(&smr_dynamic_param, pSmrPersistentMem);
	if (error != SMR_ERROR_NONE)
	{
		BSP_LCD_DisplayStringAt(10, 20, (uint8_t *)"--smr_setConfig--", LEFT_MODE);
	    return (AUDIO_ERROR_SMR);
	}
	BufferHandler.nb_bytes_per_Sample = 2;			/* 16-bit */
	BufferHandler.nb_channels = 2; 					/* stereo */
	//BufferHandler.data_ptr = PCM_Data_SMR;
	//BufferHandler.buffer_size = 32/2; 		/* just half buffer is process (size per channel) */
	BufferHandler.buffer_size = AUDIO_OUT_BUFFER_SIZE/(2*4);
	BufferHandler.mode = INTERLEAVED;

	BufferCtl.state = BUFFER_OFFSET_NONE;

	error = BSP_AUDIO_IN_Record(&BufferCtl.buff[0], AUDIO_OUT_BUFFER_SIZE/2);
	if (error > 0)
	{
		    BSP_LCD_DisplayStringAt(10, 20, (uint8_t *)"--BSP_AUDIO_IN_Record-", LEFT_MODE);
	        return (AUDIO_ERROR_SMR);
	}
}

void Audio_Process2()
{
	int32_t error = SMR_ERROR_NONE;

	if (BufferCtl.state == BUFFER_OFFSET_HALF)
	{
		BufferHandler.data_ptr = &BufferCtl.buff[0];

		error = smr_process(pBufferHandler, pBufferHandler, pSmrPersistentMem);
		if (error != SMR_ERROR_NONE)
		{
			BSP_LCD_DisplayStringAt(10, 20, (uint8_t *)"--smr_process--", LEFT_MODE);
			return (AUDIO_ERROR_SMR);
		}
	    error = smr_getConfig(&smr_dynamic_param, pSmrPersistentMem);
	    if (error != SMR_ERROR_NONE)
	    {
	    	BSP_LCD_DisplayStringAt(10, 20, (uint8_t *)"--smr_getConfig--", LEFT_MODE);
	        return AUDIO_ERROR_SMR;
	    }
	    sprintf((char *)str_pwr, "Left mean power:  %ld dB",(int32_t)((float)smr_dynamic_param.mean_level_left*0.25));
	    BSP_LCD_DisplayStringAt(10, 100, (uint8_t *)str_pwr, LEFT_MODE);
	    sprintf((char *)str_pwr, "Right mean power:  %ld dB",(int32_t)((float)smr_dynamic_param.mean_level_right*0.25));
	    BSP_LCD_DisplayStringAt(10, 120, (uint8_t *)str_pwr, LEFT_MODE);


	    BufferCtl.state = BUFFER_OFFSET_NONE;
	}
	else if (BufferCtl.state == BUFFER_OFFSET_FULL)
	{
		BufferHandler.data_ptr = &BufferCtl.buff[AUDIO_OUT_BUFFER_SIZE /2];

		error = smr_process(pBufferHandler, pBufferHandler, pSmrPersistentMem);
		if (error != SMR_ERROR_NONE)
		{
			BSP_LCD_DisplayStringAt(10, 20, (uint8_t *)"--smr_process--", LEFT_MODE);
			return (AUDIO_ERROR_SMR);
		}
		error = smr_getConfig(&smr_dynamic_param, pSmrPersistentMem);
		if (error != SMR_ERROR_NONE)
		{
			BSP_LCD_DisplayStringAt(10, 20, (uint8_t *)"--smr_getConfig--", LEFT_MODE);
			return AUDIO_ERROR_SMR;
		}
		sprintf((char *)str_pwr, "Left mean power:  %ld dB",(int32_t)((float)smr_dynamic_param.mean_level_left*0.25));
		BSP_LCD_DisplayStringAt(10, 100, (uint8_t *)str_pwr, LEFT_MODE);
		sprintf((char *)str_pwr, "Right mean power:  %ld dB",(int32_t)((float)smr_dynamic_param.mean_level_right*0.25));
		BSP_LCD_DisplayStringAt(10, 120, (uint8_t *)str_pwr, LEFT_MODE);

		BufferCtl.state = BUFFER_OFFSET_NONE;
	}
	else
	{

	}
}

void BSP_AUDIO_IN_TransferComplete_CallBack(void)
{
	BufferCtl.state = BUFFER_OFFSET_FULL;
}

void BSP_AUDIO_IN_HalfTransfer_CallBack(void)
{
	BufferCtl.state = BUFFER_OFFSET_HALF;
}