TLV320DAC3120: Tone Generator Issue

Hi Amine,

I would like to understand some things from your settings:
- Sine and Cosine operators must return its result in radians. I think your code do it like this, just want to make sure.
- You must write Hex values into device registers. (int) is taking data into hex 16bit values?
- On these lines you're not masking:
MATCH_Config[4][1] = (int) (((appData.MATCH.sine) >> 8)); //Reg 76 - SINE MSB
MATCH_Config[6][1] = (int) (((appData.MATCH.cosine) >> 8)); //Reg 78 - COSINE MSB
Don't you need to mask here too?

Is there a chance that you could read back these registers to verify the data you write?

Best regards,
-Ivan Salazar
Audio Applications Engineer - Low Power Audio & Actuators

Hi Ivan,

Thank You for your response!

I checked everything it seems fine, I fixed one of the problem which was not having a sine wave, it was due to the fact that I was choosing maximum volume, now that I control the volume it's working fine.

The issue that I still have is that the frequencies on the scope are wrong, I checked the values in I2C registers and they are calculated right and match the values and formulas in Datasheet, I even used values given in Datasheet (Table 5-18 page 37) for a 1Khz example but I get 1.7Khz, I have the same Fs=48Khz.

I configured Fs using values given in Table 5-23 page 47 of Datasheet for PLL_CLCKIN=2.048Mhz : {Register,Value}

        {0x04, 0x03}, //03 for internal generation using PPL_CLK 
        {0x05, 0x93}, // To configure PLL_CLK and sampling frequency see pages 46/47 of TLV320DAC3120 Datasheet
        {0x06, 0x0E},
        {0x07, 0x00},
        {0x08, 0x00},
        {0x0B, 0x82},
        {0x0C, 0x87},
        {0x0D, 0x00},
        {0x0E, 0x80}

 This is my code for beep generation, I used FFFFFF to have maximum beep length :

    uint8_t MATCH_Config[9][2]; //{Register address, Register value}
    appData.MATCH.sine = sinf((2 * M_PI * FHz) / (48000))*(pow(2, 15));
    appData.MATCH.cosine = (cosf(2 * M_PI * FHz / (48000))*(pow(2, 15)));
    /*
     * If a defined length for the matching beeps need to be defined use this
    appData.MATCH.cyclesNb = 349 * FHz;
    appData.MATCH.beepLength = (48000 * appData.MATCH.cyclesNb) / FHz;
     */
    appData.MATCH.volume = abs((volume * 0.63 - 63)); //Volume in DB for BEEP REG
    //appData.MATCH.volume = abs(((volume * 0.875 - 63.5)*2) - 48); // DAC VOLUME - 0 for test

    MATCH_Config[0][0] = 0x00; //Select page 0
    MATCH_Config[0][1] = 0x00;

    MATCH_Config[1][0] = 0x49;
    MATCH_Config[1][1] = 0xFF; //(((appData.MATCH.beepLength) >> 16) & 0xff) //Reg 73 - FOR DEFINED BEEPLENGTH
    MATCH_Config[2][0] = 0x4A;
    MATCH_Config[2][1] = 0xFF; //(((appData.MATCH.beepLength) >> 8) & 0xff); //Reg 74 - FOR DEFINED BEEPLENGTH
    MATCH_Config[3][0] = 0x4B;
    MATCH_Config[3][1] = 0xFF; //((appData.MATCH.beepLength) & 0xff); //Reg 75 - FOR DEFINED BEEPLENGTH
    MATCH_Config[4][0] = 0x4C;
    MATCH_Config[4][1] = ((appData.MATCH.sine) >> 8) & 0xff; //Reg 76 - SINE MSB
    MATCH_Config[5][0] = 0x4D;
    MATCH_Config[5][1] = (((appData.MATCH.sine)) & 0xff); //Reg 77 - SINE LSB
    MATCH_Config[6][0] = 0x4E;
    MATCH_Config[6][1] = (((appData.MATCH.cosine) >> 8)& 0xff); //Reg 78 - COSINE MSB
    MATCH_Config[7][0] = 0x4F;
    MATCH_Config[7][1] = (((appData.MATCH.cosine)) & 0xff); //Reg 79 - COSINE LSB

    //volume as described in Datasheet to make correspondance with binary value table (page 68 REG 65) 
    //MATCH_Config[8][0] = 0x41;
    //MATCH_Config[8][1] = appData.MATCH.volume; //Page 0 Reg 65
    MATCH_Config[8][0] = 0x47;
    MATCH_Config[8][1] = 0x80 + appData.MATCH.volume; //Page 0 Reg 71 0x80 (max volume for beep/volume of DAC controlled by slider)

    I2C_Transmit((sizeof (MATCH_Config) / 2), MATCH_Config);

Is there anything I am missing and that would make frequencies wrong?

Thank You !

Amine.

Amine,

I tried your beep settings with this script on a evaluation board:
w 30 49 00 09 60 10 b5 7e e7
w 30 41 00
w 30 47 80

I can see a correct waveform on my output.
Are you using the same overall settings for audio playback and beep? Audio playback is working fine?
Could you share the rest of your register settings to take a look?

Best regards,
-Ivan Salazar
Audio Applications Engineer - Low Power Audio & Actuators

Hi Ivan,

the wave form is fine but the sine wave's frequency doesn't seem to be correct.

Yes I keep the same overall settings to execute the beep code, I don't know what you mean by audio playback, you'll find the on-boot configuration here : https://codeshare.io/5XKeKz

Thank You!

Amine,

Clock setting registers seem to be fine for MCLK = 2.048MHz and Fs = 48kHz
The values from data sheet table 5-18 are not accurate for 1kHz tone.
The values you write are as follows?:
0x4C - 0x10
0x4D - 0xB5
0x4E - 0x7E
0x4F - 0xE8

A change in tone frequency should be related to the values you write into register 0x4C through 0x4F or the sampling frequency Fs.

Best regards,
-Ivan Salazar
Audio Applications Engineer - Low Power Audio & Actuators

Yes my code outputs those exact HEX values for 1Khz (sine/cosine), but the resulting sinewave is 1.58Khz instead of 1Khz, other frequencies are wrong too.

Is there anything wrong in my overall configuration? (that playback you were talking about?)

Using those values, do you get a 1Khz sinwave using TLV320DAC3120?

Thank You very much!

By playback I mean when you send audio to the I2S input of the device.
I have inspected your register settings and I couldn't find errors so far.
Yes, when I use 0x4C - 0x10, 0x4D - 0xB5, 0x4E - 0x7E, 0x4F - 0xE8 I get a 1kHz sine wave.
2.048MHz clock signal is coming into pin 8?
I'll keep trying to help you debug this issue.

Best regards,
-Ivan Salazar
Audio Applications Engineer - Low Power Audio & Actuators

Hi Ivan,

Thank you for your responses.

I checked the configuration and I can't see anything that would impact the beep generator's output frequency. I also tried with different board so it's not hardware.

I did take some measurements (ratio between real and expected frequency) and I get approximately the right frequency on the scope after including this factor before calculations:

Do you have any idea on what could be wrong here?

Thank You!