How to make Multiple Transmission and Single Receiver Using NRFx_SPIM Example for NRF52840-DK Board?

[rohit]

Hi,

I am Using NRF52840-DK Board. We are trying to transmit multiple data using NRFx_SPIM Example. for single reg read it is working fine.

please check below code is it correct or not?.

void MAX30003_Reg_Read(uint8_t Reg_address)
{
  nrfx_err_t err_code = 0;	
  uint32_t data=0xFF;
	//Prepare the tx buffer
  memset(SPI_TX_Buff, 0x00, sizeof(SPI_TX_Buff)); // Erases the buffer
  memset(SPI_RX_Buff, 0x00, sizeof(SPI_TX_Buff)); // Erases the buffer
  SPI_TX_Buff[0] = (Reg_address<<1) | 0x1; // should be SPI_TXBuff[0], I assume RREG = 0x1;
//Create the transfer descriptor
  nrfx_spim_xfer_desc_t xfer_desc4 = NRFX_SPIM_XFER_TRX(SPI_TX_Buff, sizeof(SPI_TX_Buff), SPI_RX_Buff, sizeof(SPI_TX_Buff));
	nrfx_spim_xfer_desc_t xfer_desc5 = NRFX_SPIM_XFER_TRX((data << 16), sizeof(data), SPI_RX_Buff, sizeof(data));
	nrfx_spim_xfer_desc_t xfer_desc6 = NRFX_SPIM_XFER_TRX((data << 8), sizeof(data), SPI_RX_Buff, sizeof(data));
	nrfx_spim_xfer_desc_t xfer_desc7 = NRFX_SPIM_XFER_TRX(data, sizeof(data), SPI_RX_Buff, sizeof(data));
//Initiate the transfer
  err_code = nrfx_spim_xfer(&spi, &xfer_desc4, 0);
	err_code = nrfx_spim_xfer(&spi, &xfer_desc5, 0);
	err_code = nrfx_spim_xfer(&spi, &xfer_desc6, 0);
	err_code = nrfx_spim_xfer(&spi, &xfer_desc7, 0);
  APP_ERROR_CHECK(err_code);
//  while (spi_xfer_done == true);
}

I am refer below code :

uint32_t MAX30003::readRegister(const Registers_e reg)
{
    uint32_t data = 0;
    
    m_cs = 0;
    m_spiBus.write((reg << 1) | 1);
    data |= (m_spiBus.write(0xFF) << 16);
    data |= (m_spiBus.write(0xFF) << 8);
    data |= m_spiBus.write(0xFF);
    m_cs = 1;
    
    return data;
}   

please help me for that. 

Thanks 

rohit

[Jørgen Holmefjord]

Hi,

You are over-complicating the transfer. Just create a large enough receive buffer and to the transfer and receive in a single operation.

Something like this should work:

uint8_t SPI_TX_Buff;
uint8_t SPI_RX_Buff[4];

uint32_t MAX30003_Reg_Read(uint8_t Reg_address)
{
  nrfx_err_t err_code = 0;	
  uint32_t data = 0;

  //Prepare the tx buffer
  memset(SPI_RX_Buff, 0x00, sizeof(SPI_RX_Buff)); // Erases the buffer
  SPI_TX_Buff = ((Reg_address << 1) | 0x01); 

  //Create the transfer descriptor
  nrfx_spim_xfer_desc_t xfer_desc = NRFX_SPIM_XFER_TRX(&SPI_TX_Buff, sizeof(SPI_TX_Buff), SPI_RX_Buff, sizeof(SPI_TX_Buff));

  //Initiate the transfer
  spi_xfer_done == false;
  err_code = nrfx_spim_xfer(&spi, &xfer_desc, 0);
  APP_ERROR_CHECK(err_code);
  
  while (spi_xfer_done == false);
  
  data |= (SPI_RX_Buff[1] << 16);
  data |= (SPI_RX_Buff[2] << 8);
  data |= SPI_RX_Buff[3];
  
  return data;
}

Best regards,
Jørgen

[rohit]

Hi,

Thanks for the suggestion,

This is work when I make below changes:

1) change condition from  while (spi_xfer_done == false)    to     while (spi_xfer_done == true);

2) SPI_TX_Buff = ((Reg_address << 1) | 0x01);  to   SPI_TX_Buff[0] = ((Reg_address << 1) | 0x01); 

May I know is it correct?

Thanks,

rohit

uint8_t MAX30003_Reg_Read(uint8_t Reg_address)
{
  nrfx_err_t err_code = 0;	
  uint32_t data;
  //Prepare the tx buffer
  memset(SPI_RX_Buff, 0x00, sizeof(SPI_RX_Buff)); // Erases the buffer
  SPI_TX_Buff[0] = ((Reg_address << 1) | 0x01); 
  //Create the transfer descriptor
  nrfx_spim_xfer_desc_t xfer_desc = NRFX_SPIM_XFER_TRX(&SPI_TX_Buff, sizeof(SPI_TX_Buff), SPI_RX_Buff, sizeof(SPI_TX_Buff));
  //Initiate the transfer
  spi_xfer_done == false;
  err_code = nrfx_spim_xfer(&spi, &xfer_desc, 0);
  APP_ERROR_CHECK(err_code);
  while (spi_xfer_done == true);
  data |= (SPI_RX_Buff[1] << 16);
  data |= (SPI_RX_Buff[2] << 8);
  data |= SPI_RX_Buff[3];
  return data;
}