ESP32C3 > SPI > Single Transfer Mode

[BugSimpson]

I have another question about the SPI interface in single transfer mode.

You can fill the registers from SPI_W0_REG - SPI_W15_REG with data.

When I call my function, it sends the contents of SPI_W0_REG, but SPI_W1_REG is also filled with data.

How does it work that it also sends the second register?

Code: Untitled.c Select all

void spi_write_bytes( uint8_t *_data, uint8_t _length )

{

  if (_length > 64) 

  {

    _length = 64;

  }



  uint32_t words = (_length + 3) / 4;  //16 max

  uint32_t wordsBuf[16] = {0};

  uint8_t *bytesBuf = (uint8_t *)wordsBuf;



  for (uint8_t i = 0; i < _length; i++)

  {

    *bytesBuf++ = *_data++;

  }

  

  REG_WRITE( SPI_MS_DLEN_REG, ( 8 * _length ) -1 );



  for (uint8_t i = 0; i < words; i++)

  {

    REG_WRITE( SPI_Wn_REG( i ), wordsBuf[i] );

  }

  

  REG_SET_BIT( SPI_CMD_REG, SPI_UPDATE_bm );

  while ( REG_READ( SPI_CMD_REG ) & SPI_UPDATE_bm );



  REG_SET_BIT( SPI_CMD_REG, SPI_USR_bm );

  while ( REG_READ( SPI_CMD_REG ) & SPI_USR_bm );  



  spi_poll_trans_done_int();

}