Use PCM5102 with STM32

PCM5102 and STM32

Here are my tiny notes about the connection of PCM5102 DAC to STM32F401 Nucleo board.
I2S interface requires three wires to work:

• SCK is officially called as “continuous serial clock (SCK)”, but also you can found “bit clock” name. It is just the same clock as usual in the SPI interface.
• Word Select clock is used to select, which cannel is active now, 0 for left channel, 1 for right. It also called called “left-right clock (LRCLK)” or “frame sync (FS)”.
• Serial data - actual data.

CubeMX settings

Wiring diagram

My board has such pins:

| 3.3V | 3.3V on Nucleo board  |
| FLT  | Filter select, grounded: select normal latency, grounded  |
| DMP  | De-emphasis control, grounded(OFF)  |
| SCL  | System clock input, in datasheet SCK pin. System clock is internally generated, it should not be wired anywhere  |
| BCK  | Audio data bit clock input. In I2S terminology is equivalent to serial clock(SCK) I've connected it to `PB10 > I2S2_CK` |
| DIN  | Audio data input. This is Serial Data pin, I've connected it to `PC3 > I2S2_SD` |
| LCK  | Is LRCK in PCM5102 datasheet, which is Audio data word clock input. It is used to switch data for left and right channel. In I2S is I2SX_WS pin, means "Word Select" pin. Connect it to `PB12 > I2S2_WS` |
| FMT  | Audio Format Selection, we select I2S, so this should be grounded  |
| XMT  | In dataseet is XSMT, which is mute control, should be HIGH to unmute.  |

As we see, only three wires used for actual data transmission, others are miscellaneous.

Test code

Actual test code is quite simple, here we just put triangle wave to I2S via HAL_I2S_Transmit function.

const uint16_t triangle_wave[]  = {
0x400,0x800,0xc00,0x1000,0x1400,0x1800,0x1c00,0x2000,
0x2400,0x2800,0x2c00,0x3000,0x3400,0x3800,0x3c00,0x4000,
0x4400,0x4800,0x4c00,0x5000,0x5400,0x5800,0x5c00,0x6000,
0x6400,0x6800,0x6c00,0x7000,0x7400,0x7800,0x7c00,0x8000,
0x83ff,0x87ff,0x8bff,0x8fff,0x93ff,0x97ff,0x9bff,0x9fff,
0xa3ff,0xa7ff,0xabff,0xafff,0xb3ff,0xb7ff,0xbbff,0xbfff,
0xc3ff,0xc7ff,0xcbff,0xcfff,0xd3ff,0xd7ff,0xdbff,0xdfff,
0xe3ff,0xe7ff,0xebff,0xefff,0xf3ff,0xf7ff,0xfbff,0xffff,
0xfbff,0xf7ff,0xf3ff,0xefff,0xebff,0xe7ff,0xe3ff,0xdfff,
0xdbff,0xd7ff,0xd3ff,0xcfff,0xcbff,0xc7ff,0xc3ff,0xbfff,
0xbbff,0xb7ff,0xb3ff,0xafff,0xabff,0xa7ff,0xa3ff,0x9fff,
0x9bff,0x97ff,0x93ff,0x8fff,0x8bff,0x87ff,0x83ff,0x8000,
0x7c00,0x7800,0x7400,0x7000,0x6c00,0x6800,0x6400,0x6000,
0x5c00,0x5800,0x5400,0x5000,0x4c00,0x4800,0x4400,0x4000,
0x3c00,0x3800,0x3400,0x3000,0x2c00,0x2800,0x2400,0x2000,
0x1c00,0x1800,0x1400,0x1000,0xc00,0x800,0x400,0x0,
};

int main(void)
{
  HAL_Init();
  SystemClock_Config();
  MX_GPIO_Init();
  MX_I2S2_Init();
  MX_USART2_UART_Init();
  while (1)
  {

    /* Here is our actual code */
    HAL_I2S_Transmit(&hi2s2, triangle_wave, sizeof(triangle_wave)/sizeof(triangle_wave[0]), 1000);
  }
}

That is all, you should hear triangle wave in connected to PCM5102 module.