How to read I2S configuration and print in UART using NRF52-DK ?

RE: How to read I2S configuration and print in UART using NRF52-DK ?

Cecil Benjamin L — Thu, 07 Jan 2021 13:52:22 GMT

As you said earlier it doesnt matter if the value sent has 0X00"24bits" or 0xFF"24bits" I had to process the data to store as you had suggested. And this works for me. Thanks for the help.

Printing the buffer data is relative slower than i2s buffer updates. So I used the raw data and stored directly it in a sd. It works fine.

RE: How to read I2S configuration and print in UART using NRF52-DK ?

Edvin — Tue, 24 Nov 2020 15:29:54 GMT

Did you try to check the bit and/or byte order of the data coming from the TLV? Bit byte swapping should be done similar to the way it is done in the snippet. And remember that your samples are 20 bit, so it looks like your example of 0xFD5A is missing 4 bits?

BR,

Edvin

RE: How to read I2S configuration and print in UART using NRF52-DK ?

Cecil Benjamin L — Tue, 24 Nov 2020 11:19:35 GMT

Analog mic -> ADC I2S out (TLV320ADC3100)-> I2S -> Raspberry Pi (RPi) (master)

Analog mic -> ADC I2S out (TLV320ADC3100)-> I2S -> nRF(master)

This is the experimental setup. The i2s clocks generated by RPi and by nRF are of same value. Adc configuration are also same.

I couldn't pinpoint the exact problem why nRF based implementation doesn't work.

RE: How to read I2S configuration and print in UART using NRF52-DK ?

Edvin — Tue, 24 Nov 2020 10:25:23 GMT

[quote user="Cecil Benjamin L"]I used the same I2S clock - BCLK, LRCK and I2C configuration for the ADC in Raspberry Pi. The experimental setup works in Raspberry Pi.[/quote]

I must say I am a bit confused.

Your setup is:

I2S microphone -> some device -> ADC -> I2S -> nRF?

Was this the same in your Raspberry Pi setup?

I2S microphone -> some device -> ADC -> I2S -> Raspberry Pi?

RE: How to read I2S configuration and print in UART using NRF52-DK ?

Cecil Benjamin L — Tue, 24 Nov 2020 10:00:11 GMT

My current nRF based experimental setup was replicated using Raspberry Pi few days back. I used the same I2S clock - BCLK, LRCK and I2C configuration for the ADC in Raspberry Pi. The experimental setup works in Raspberry Pi.

I plotted the raw data of nRF I2S SDIN in Matlab and also used audacity to convert the data to audio. Doesn't look like a sine wave at all.

I tired using a logic analyzer but seems like I2S decode in Picoscope doesn't help much.

RE: How to read I2S configuration and print in UART using NRF52-DK ?

Edvin — Tue, 24 Nov 2020 08:55:42 GMT

How do you confirm that the data is correct?

Did you look into the snippets I suggested in my first reply?

RE: How to read I2S configuration and print in UART using NRF52-DK ?

Cecil Benjamin L — Tue, 24 Nov 2020 08:28:15 GMT

Currently I am using printf(); statement to print the buffer values. I think i can solve this NRF log problem later. My problem is the I2S data stored can't be verified. I printed all the values and used audacity to convert the raw data to an audio file. It seems it is always noise. I am sure the ADC configuration is correct because I am using exact setup using raspberry pi. Can you suggest on how I can handle the I2S data and confirm the received data is correct.

RE: How to read I2S configuration and print in UART using NRF52-DK ?

Edvin — Tue, 24 Nov 2020 08:22:59 GMT

I am not sure why it is stuck (?). Do you mean stuck, or actually struck?

What does it look like? does NRF_LOG_INFO(); never return? If so, is it the first call to NRF_LOG_INFO, or after a while?

Please note that NRF_LOG_INFO() doesn't print immediately to the log. The log is printed when NRF_LOG_PROCESS() is called later in your main loop.

Perhaps you can try to change:

#define NRF_LOG_DEFERRED 1
to
#define NRF_LOG_DEFERRED 0

in your sdk_config.h file. Does that help?

If not, can you replicate the issue in a project that doesn't require any external components other than the DK, and upload it here?

BR,

Edvin

RE: How to read I2S configuration and print in UART using NRF52-DK ?

Cecil Benjamin L — Mon, 23 Nov 2020 14:02:46 GMT

NRF_LOG_INFO("%3u: OK", m_blocks_transferred);

struck at above line.

The loop for (i = 0; i< I2S_DATA_BLOCK_WORDS; i++) doesn't finish because of this NRF_LOG problem.

RE: How to read I2S configuration and print in UART using NRF52-DK ?

Edvin — Mon, 23 Nov 2020 11:23:26 GMT

Hello Cecil,

where is NRF_LOG stuck in a loop problem? What do you mean by this? Do you mean that the logs doesn't print correctly, or that it prints forever in a loop, e.g. the loop:

for (i = 0; i< I2S_DATA_BLOCK_WORDS; i++)

loop doesn't finish?

BR,

Edvin

RE: How to read I2S configuration and print in UART using NRF52-DK ?

Cecil Benjamin L — Thu, 19 Nov 2020 12:50:43 GMT

Can you suggest a solution for NRF LOG struck in a loop problem. I am print the whole buffer in a loop.

static bool check_samples(uint32_t const * p_block)
{
    // [each data word contains two 16-bit samples]
    uint16_t i;
    for (i = 0; i < I2S_DATA_BLOCK_WORDS; ++i)
    {
        uint32_t const * p_word = &p_block[i];
        uint32_t sample_actual = *p_word;
        NRF_LOG_INFO("P_word: 0x%x ",sample_actual);
        //Process data for SD card storage/ Uart print
    }
    NRF_LOG_INFO("%3u: OK", m_blocks_transferred);
    return true;
}

RE: How to read I2S configuration and print in UART using NRF52-DK ?

Cecil Benjamin L — Thu, 19 Nov 2020 12:01:55 GMT

Sorry for a late response, rest of the sample values are correct. It doesnt matter if it is 0x000 or 0xFFF.

I want to know how the I2S data received from the microphone is stored in the buffer. ex. 0xFD5A from the mic dout will be stored as same as MSB of mic dout.....LSB of mic dout (0xFD5A) or LSB of mic dout .......MSB of mic dout (0x5AFD) in the I2S buffer.

RE: How to read I2S configuration and print in UART using NRF52-DK ?

Edvin — Fri, 06 Nov 2020 12:39:29 GMT

Sorry that this is a bit messy, but I also just read the messages that you sent me.

The I2S will store one sample in a buffer array. The buffer consists of 32 bit values. Try memsetting the buffer to either 0x00 or 0xFF (0x00000000 or 0xFFFFFFFF) before you sample, and see if it is more consistent.

If you either way have to process the data (stripping away the first 12 bits of each sample) does it matter that they in some cases are 0x000 and in some cases 0xFFF? Is the rest of the sample correct?

BR,

Edvin

RE: How to read I2S configuration and print in UART using NRF52-DK ?

Cecil Benjamin L — Fri, 06 Nov 2020 12:12:47 GMT

I am watching the m_buffer_rx[2][512], which is the NRF_I2S_DRV_Buffer for RX. I exported one set of the sample while debugging the project from the watch. I access the buffer from a pointer which is set to NULL each time after processing the buffer values. I am using the I2S code edited for 24-bit word length.

RE: How to read I2S configuration and print in UART using NRF52-DK ?

Edvin — Fri, 06 Nov 2020 11:47:41 GMT

How is the data in the 512_Samples.txt generated?

If the values are from the RAM, and not memset to 0x00000000 or 0xFFFFFFFF before it is sampled, it may be that the remaining bytes that are not written by the I2S are old (garbage) RAM values.

RE: How to read I2S configuration and print in UART using NRF52-DK ?

Cecil Benjamin L — Fri, 06 Nov 2020 10:42:36 GMT

Hello Edvin,

I have attached one set of I2S samples in a text file. Some times i get 0xFF'24bits data' other times it is 0x00'24bitdata'. I used only one mic through the left channel.devzone.nordicsemi.com/.../512_5F00_Samples.txt.

I still have a doubt is the data is stored as 0xFF"4bits as 0 ,20-bits data " or 0xFF"20-bits data, 4bits as 0"

Below is the snippet.

static bool check_samples(uint32_t const * p_block)
{
    // [each data word contains two 16-bit samples]
    uint16_t i;
    for (i = 0; i < I2S_DATA_BLOCK_WORDS; ++i)
    {
        uint32_t const * p_word = &p_block[i];
        uint32_t sample_actual = *p_word;
        NRF_LOG_INFO("P_word: 0x%x ",sample_actual);
        //Process data for SD card storage/ Uart print
    }
    NRF_LOG_INFO("%3u: OK", m_blocks_transferred);
    return true;
}

RE: How to read I2S configuration and print in UART using NRF52-DK ?

Edvin — Thu, 05 Nov 2020 13:37:48 GMT

Hello,

So you do receive values with 0xFF'24bit-value'?

If the external ADC is using a 20 bit I2S, you must use the 24 bit, in order to capture all of the data.

2. Have you tried to manage this? I guess you need to do some bit shifting in order to store this. I assume you want to store samples in whole bytes on the SD card. If each sample is 20 bits, and you store 8 samples, you have 160 bits=20 bytes. So perhaps you want to wait until you have 8 samples (you can use more/less samples, as long as it adds up to n*8 bits. 2 samples are sufficient, but you probably want to store up a decent amount of data before writing to the SD card.

// Let us say you stored 8 samples, and they are stored in uint32_t samples[0] -> samples[7]:
// The actual data are the last 5 bytes of the uint32_t sample[i]: sample[i] & 0x000FFFFF;

static void process_data(uint32_t samples[], uint8_t length, uint8_t processed_data[])
{
    memset(processed_data, 0x00, sizeof(processed_data); //sizeof(processed_data) should be 5/2*length.
    
    processed_data[0] |= (uint8_t)((samples[0] & 0x000FF000) >> 12);
    processed_data[1] |= (uint8_t)((samples[0] & 0x00000FF0) >>  4);
    processed_data[2] |= (uint8_t)((samples[0] & 0x0000000F) <<  4);
    processed_data[2] |= (uint8_t)((samples[1] & 0x000F0000) >> 16);
    processed_data[3] |= (uint8_t)((samples[1] & 0x0000FF00) >> 16);
    processed_data[4] |= (uint8_t)((samples[1] & 0x000000FF) <<  0);
    
    // At this point, the 2 first buffers (2*20 bits = 40 bits) are stored in the first 5 bytes (5*8bits = 40 bits)
    // transform this into a for loop to handle the entire length:
    
    for (uint8_t i=0; i<length/2; i++)
    {
        processed_data[2*i+0] |= (uint8_t)((samples[5*i+0] & 0x000FF000) >> 12);
        processed_data[2*i+1] |= (uint8_t)((samples[5*i+0] & 0x00000FF0) >>  4);
        processed_data[2*i+2] |= (uint8_t)((samples[5*i+0] & 0x0000000F) <<  4);
        processed_data[2*i+2] |= (uint8_t)((samples[5*i+1] & 0x000F0000) >> 16);
        processed_data[2*i+3] |= (uint8_t)((samples[5*i+1] & 0x0000FF00) >> 16);
        processed_data[2*i+4] |= (uint8_t)((samples[5*i+1] & 0x000000FF) <<  0);
    }
}

RTT print issue:

From where do you print this, and how do you attempt to print it? Can you show some snippets?

Best regards,

Edvin