nRF52840 SPI does not update register values in MAX30003 module

[Giovani_Giorgio]

Hi,

I want to communicate with MAX30003 ECG chip with my nRF52840 board.
I am able to read MAX30003 register values but I cannot write new values to the registers.
Not some specific register but all of them. So I must have done something wrong here...

For example when try to read the INFO register (address 0x0F) of the MAX30003 I get the correct value (chip ID) as I expect which is 0x5131C0 .

Then when I try to enable the ECG_EN bit of the CNFG_GEN register (with address 0x10), I send through SPI the following value:
0x080004( where 08 corresponds to the bit ECG_EN that I want to enable).
When I read back the value of this register I get the initial value (0x00000004) , before I changed it.

This happens with all registers...

here is what I get in the debugger

Here is my code for the spi

void spi_event_handler(nrf_drv_spi_evt_t const * p_event, void * p_context)
{
  switch(p_event->type){

    case NRF_DRV_SPI_EVENT_DONE:
    
        spi_xfer_done = true;
        break;
    default:
        NULL;
  }
}

// SPI Initialization
void spi_init(void){ 

    nrf_delay_ms(100); 

    nrf_drv_spi_config_t spi_config  = NRF_DRV_SPI_DEFAULT_CONFIG;   
    spi_config.ss_pin   =  SPI_CS_PN;  // NRF_DRV_SPI_PIN_NOT_USED;  
    spi_config.miso_pin = SPI_MISO_PN; 
    spi_config.mosi_pin = SPI_MOSI_PN; 
    spi_config.sck_pin  = SPI_SCK_PN;  
    spi_config.frequency = NRF_SPI_FREQ_250K;
    spi_config.bit_order = NRF_SPI_BIT_ORDER_MSB_FIRST;
    //spi_config.orc = 0xEE;
    spi_config.mode = NRF_SPI_MODE_0;
    APP_ERROR_CHECK(nrf_drv_spi_init(&m_spi, &spi_config, spi_event_handler, NULL));
}

here are the pin settings

//------SPI------
#define SPI_MOSI_PN    NRF_GPIO_PIN_MAP(0,20)     
#define SPI_SCK_PN     NRF_GPIO_PIN_MAP(0,13)      
#define SPI_CS_PN      NRF_GPIO_PIN_MAP(0,24)       
#define SPI_MISO_PN    NRF_GPIO_PIN_MAP(0,22) 

here are the functions for writing/reading to/from the MAX30003

// SPI read data.    Function returns a register's value in uint32_t form. It also saves the value in ECG_arrayRCV[]
uint32_t ECG_RD_reg(uint8_t reg){  
                      
     uint32_t reg_data = 0;
     uint8_t array_len = 4;

      spi_xfer_done = false;
      ECG_arrayTRF[0] = ((reg << 1) | SPI_RREG );     // prepare data for reception (register to be read + read bit)
      ECG_arrayTRF[1] = 0;
      ECG_arrayTRF[2] = 0;
      ECG_arrayTRF[3] = 0;

      NRF_LOG_INFO( "Send register Address + Read: 0x%02X%02X%02X%02X", ECG_arrayTRF[0], ECG_arrayTRF[1] ,ECG_arrayTRF[2] ,ECG_arrayTRF[3]);
 
      //err_code = nrf_drv_spi_transfer(&m_spi, array_tr, array_len, array_rcv, array_len);  
     err_code = nrf_drv_spi_transfer(&m_spi, ECG_arrayTRF, array_len, ECG_arrayRCV, array_len); 
     while(spi_xfer_done == false);
     APP_ERROR_CHECK(err_code);

     NRF_LOG_INFO( "Register Returns: 0x%02X%02X%02X%02X", ECG_arrayRCV[0], ECG_arrayRCV[1] ,ECG_arrayRCV[2] ,ECG_arrayRCV[3]);
    

     reg_data |= (uint32_t) (ECG_arrayRCV[0] << 24);     // build a uint32_t from the arrayRCV
     reg_data |= (uint32_t) (ECG_arrayRCV[1] << 16);     // ByteH is here, since MSB comes out first from the MAX30003 FIFO 
     reg_data |= (uint32_t) (ECG_arrayRCV[2] <<  8);     // ByteM
     reg_data |= (uint32_t) (ECG_arrayRCV[3] <<  0);     // ByteL

     return reg_data;
}

// SPI send data  
void ECG_WR_reg(uint8_t reg, uint32_t data){

  uint8_t array_dum[4] = {0};
  uint8_t array_len = 4;

  spi_xfer_done = false;
  ECG_arrayTRF[0] = ((reg << 1) & SPI_WREG);        // register to be written + write bit
  ECG_arrayTRF[1] = (uint8_t)((data & 0x00FF0000) >> 16);
  ECG_arrayTRF[2] = (uint8_t)((data & 0x0000FF00) >> 8);
  ECG_arrayTRF[3] = (uint8_t)((data & 0x000000FF) >> 0);

  NRF_LOG_INFO( "Send reg address + Write: 0x%02X%02X%02X%02X", ECG_arrayTRF[0], ECG_arrayTRF[1] ,ECG_arrayTRF[2] ,ECG_arrayTRF[3]);

  err_code = nrf_drv_spi_transfer(&m_spi, ECG_arrayTRF, 4, ECG_arrayRCV, 4);
  while(spi_xfer_done == false);
  APP_ERROR_CHECK(err_code);
}

and here is my main()

    uint32_t res = 0;
    NRF_LOG_INFO("HELLO");
    spi_init();    // Initialize SPI   
 
    NRF_LOG_INFO("ECG_INFO: 0x%08X", ECG_RD_reg(ECG_INFO));
  
   
      
    res = 0x080004;
    ECG_WR_reg(ECG_CNFG_GEN, res);    // Enable [ECG channel, DC Lead-Off Detect, Resistive Bias on Pos/Neg EI], R_bias = 100MU
    nrf_delay_ms(100);
    NRF_LOG_INFO("ECG_CNFG_GEN --> What I get: 0x%06X   ---  What I want: 0x%06X", ECG_RD_reg(ECG_CNFG_GEN), res);

Any ideas what I am doing wrong?

Thank you!

[azwin]

check the pin setting esp : #define SPI_MISO_PN    NRF_GPIO_PIN_MAP(0,22) . give any other pin number n check 

[harry4951]

Hardware: If you are using max30003wing breakout board, try to connect both breakout GNDs to the DK.

Software: I manage to read the data 0x080004 back using max30003wing breakout. I am using the following setup, the rest are the same.

#define SPI_INSTANCE 1 /**< SPI instance index. */
static const nrf_drv_spi_t m_spi = NRF_DRV_SPI_INSTANCE(SPI_INSTANCE); /**< SPI instance. */
static volatile bool spi_xfer_done; /**< Flag used to indicate that SPI instance completed the transfer. */

#define SPI_MISO_PIN NRF_GPIO_PIN_MAP(1, 8)
#define SPI_MOSI_PIN 30
#define SPI_SCK_PIN 31
#define SPI_SS_PIN NRF_GPIO_PIN_MAP(1, 7)

[rmptxf]

I'm also struggling with this sensor and using the wing breakout too.

Here I wasn't even able to get a valid chip id. That's at startup and not right after a chip reset.

Edit1: 

I was able to get a valid chip id, but after using a 1.8v VDD. And that's with the wing module, that is stated to work with 3.3v.

Edit2:

So, yes it turns out that a 1.8v VDD did it. Now it is working fine. Able to get the ecg samples on the fifo buffer.

There is an mbed based library for this sensor that would be good to check and port to the nRF SDKs: https://os.mbed.com/users/h_keyur/code/MAX_IOT_KIT/

[Giovani_Giorgio]

Hi,
what is wrong with pin (0,22)?

[Giovani_Giorgio]

Hi, no I am not using the max30003wing I am using my custom board with MAX300003 and nRF52840 chip
and I cannot modify the pins unfortunately