SPI communication between slave Arduino and Master Raspberry Pi

Projects Networking, Protocols, and Devices
6

Sorry for wasting your time.

I use the ESP32's API when I do SPI thingies.
I have some code here where I write 32 bits to the SPI bus, I doubt it will be of help but I post it just in case.

void fReadSPIdata16bits( spi_device_handle_t &h, int _address )
{
  uint8_t address = _address;
  esp_err_t intError;
  spi_transaction_t trans_desc;
  trans_desc = { };
  trans_desc.addr =  0;
  trans_desc.cmd = 0;
  trans_desc.flags = 0;
  trans_desc.length = (8 * 3); // total data bits
  trans_desc.tx_buffer = txData;
  trans_desc.rxlength = 8 * 2 ; // Number of bits NOT number of bytes
  trans_desc.rx_buffer = rxData;
  txData[0] = address | 0x80;
  intError = spi_device_transmit( h, &trans_desc);
  low = rxData[0]; high = rxData[1];
  //  if ( intError != 0 )
  //  {
  //    Serial.print( " WHO I am LSM9DS1. Transmitting error = ");
  //    Serial.println ( esp_err_to_name(intError) );
  //  }
} // void fSendSPI( uint8_t count, uint8_t address, uint8_t DataToSend)
////
int fWriteSPIdata8bits( spi_device_handle_t &h, int _address, int _sendData )
{
  uint8_t address =  _address;
  uint8_t sendData = _sendData;
  esp_err_t intError;
  spi_transaction_t trans_desc;
  trans_desc = { };
  trans_desc.addr =  0;
  trans_desc.cmd = 0;
  trans_desc.flags = 0;
  trans_desc.length = (8 * 2); // total data bits
  trans_desc.tx_buffer = txData;
  trans_desc.rxlength = 0 ; // Number of bits NOT number of bytes
  trans_desc.rx_buffer = NULL;
  txData[0] = address  & 0x7F;
  txData[1] = sendData;
  intError = spi_device_transmit( h, &trans_desc);
  //  //  if ( intError != 0 )
  //  //  {
  //  //    Serial.print( " LSM9DS1_REGISTER_CTRL_REG6_XL. Transmitting error = ");
  //  //    Serial.println ( esp_err_to_name(intError) );
  //  //  }
  return intError;
} // void fWriteSPIdata8bits(  spi_device_handle_t &h, uint8_t address, uint8_t sendData )
//
int fWriteSPIdata8bits2( spi_device_handle_t &h, int _sendData )
{
  rxData[0] = 0x00;
  // uint8_t address =  _address;
  uint8_t sendData = _sendData;
  esp_err_t intError;
  spi_transaction_t trans_desc;
  trans_desc = { };
  trans_desc.addr =  0;
  trans_desc.cmd = 0;
  trans_desc.flags = 0;
  trans_desc.length = (8 * 2); // total data bits
  trans_desc.tx_buffer = txData;
  trans_desc.rxlength = 8 ; // Number of bits NOT number of bytes
  trans_desc.rx_buffer = rxData;
  txData[0] = sendData;
  // txData[0] = address;
  // txData[1] = sendData;
  intError = spi_device_transmit( h, &trans_desc);
  if ( intError == 0 )
  {
    return rxData[0];
  }
  else
  {
  return intError;  
  }
} // void fWriteSPIdata8bits(  spi_device_handle_t &h, uint8_t address, uint8_t sendData )
////
int fWriteSPIdata32bits( spi_device_handle_t &h, int _sendData0, int _sendData1, int _sendData2, int _sendData3 )
{
  // uint8_t address =  _address;
  // uint8_t sendData = _sendData;
  esp_err_t intError;
  spi_transaction_t trans_desc;
  trans_desc = { };
  trans_desc.addr =  0;
  trans_desc.cmd = 0;
  trans_desc.flags = 0;
  trans_desc.length = (8 * 4); // total data bits
  trans_desc.tx_buffer = txData;
  trans_desc.rxlength = 0 ; // Number of bits NOT number of bytes
  trans_desc.rx_buffer = NULL;
  txData[0] = (uint8_t)_sendData0; // command bits
  txData[1] = (uint8_t)_sendData1; // lower bits
  txData[2] = (uint8_t)_sendData2; // higher bits
  txData[3] = (uint8_t)_sendData3; // address
  intError = spi_device_transmit( h, &trans_desc);
  return intError;
} // void fWriteSPIdata8bits(  spi_device_handle_t &h, uint8_t address, uint8_t sendData )
////
int fReadSPIdataXbits( spi_device_handle_t &h, int _readaddress, int *rxbuf, int rxlen )
{
  uint8_t address = _readaddress;
  int8_t rxBuf[rxlen] = {0};
  esp_err_t intError;
  spi_transaction_t trans_desc;
  trans_desc = { };
  trans_desc.addr =  0;
  trans_desc.cmd = 0;
  trans_desc.flags = 0;
  trans_desc.length = ( (8 * 1) + (8 * rxlen)); // total data bits
  trans_desc.tx_buffer = txData ;
  trans_desc.rxlength = 8 * rxlen ; // Number of bits NOT number of bytes
  trans_desc.rx_buffer = rxBuf;
  txData[0] = address;
  // txData[1] = 0x00;
  intError = spi_device_transmit( h, &trans_desc);
  for (int i = 0; i < rxlen; i++)
  {
    rxbuf[i] = rxBuf[i];
  }
 return intError;
} // int fReadSPIdataXbits( spi_device_handle_t &h, int _readaddress, int *rxbuf, int rxlen )