SPI Data Mode for AFE4490

Mohammad,

SPI mode 0 should work.

Thanks for the verification on that. I'm currently trying to debug some SPI communication issues. Would be so kind to tell me if the read and write functions I am using below look correct?

void RegisterWrite (uint8_t address, uint32_t data)
{
    digitalWrite (SPISTE, LOW); // enables device
    SPI.transfer (address); //sends register address
    SPI.transfer ((data >> 16) & 0xFF); // top 8 bits
    SPI.transfer ((data >> 8) & 0xFF); //middle 8 bits
    SPI.transfer (data & 0xFF); //bottom 8 bits    
    digitalWrite (SPISTE, HIGH); // disables device
}

uint32_t RegisterRead (uint8_t address)
{       
    uint32_t data=0;
    digitalWrite (SPISTE, LOW); // enables device
    SPI.transfer (address); // sends register address
    data |= (SPI.transfer (0)<<16); // reading the top 8 bits of data
    data |= (SPI.transfer (0)<<8); // reading the middle 8 bits of data
    data |= SPI.transfer (0); // reading the bottom 8 bits of data
    digitalWrite (SPISTE, HIGH); // disables device
    return data; // return the read 24 bits of data
}

SPI.transfer and digitalWrite are from the Arduino library.

http://arduino.cc/en/Reference/SPITransfer

http://arduino.cc/en/Reference/digitalWrite

The code snippet you provided seems valid.

Can you post your AFE4490 driver code API for the Arduino Platform?

Hi Praveen,

I'm still working on the driver code. I was testing to see if I could read and write to the registers using the above functions and wanted to double check. The good news is that I am able to get the LEDs on the DCM03 to light up so far!

Ok, I'm simply trying to write to some registers and read the values back. Here's my result. Any ideas why the register values are read incorrectly?

void setup() is only run once. void loop() runs repeatedly and produces the console output shown.

Btw, the LEDs do not light up.

Code Below

#include <intrinsics.h>
#include <string.h>
#include <SPI.h>
#include "AFE4490.h"

const int SCLK = 13;
const int SOMI = 12;
const int SIMO = 11;
const int SPISTE = 10;
const int ADC_RDY = 9;

void AFE4490Initialize (void);
void RegisterWrite (uint8_t address, uint32_t data);
uint32_t RegisterRead (uint8_t address);

void setup()
{
   Serial.begin(9600);
    
   SPI.begin();
   pinMode (SOMI, INPUT);
   pinMode (SPISTE, OUTPUT);
   pinMode (SCLK, OUTPUT);
   pinMode (SIMO, OUTPUT);
   pinMode (ADC_RDY, INPUT);
   
   SPI.setClockDivider (SPI_CLOCK_DIV128); //Divides 8 MHZ clock by 128 = 62.5 KHz
   SPI.setDataMode (SPI_MODE0);
   SPI.setBitOrder (MSBFIRST);
 
   AFE4490Initialize(); //Function used for initializing the AFE4490
   
}

void loop()
{
  RegisterWrite(CONTROL0, 0x000001); //SPI_Read Enable
  Serial.println(RegisterRead(LEDCNTRL), HEX);
  Serial.println(RegisterRead(TIAGAIN), HEX);
  Serial.println(RegisterRead(TIA_AMB_GAIN), HEX);
  Serial.println("\n");
  delay(1000);
}

////////////////////Functions Below/////////////////////////

void AFE4490Initialize (void)
{
    Serial.println("Initializing \n");
    RegisterWrite(CONTROL0, 0x000008); //SW_RST
    RegisterWrite(LEDCNTRL, 0x11414);
    RegisterWrite(TIAGAIN,0x008002);
    RegisterWrite(TIA_AMB_GAIN,0x004404);
    Serial.println("Initialization Complete. \n");
}

void RegisterWrite(uint8_t address, uint32_t data)
{
    digitalWrite (SPISTE, LOW); // enable device
    SPI.transfer (address); // send address to device
    SPI.transfer ((data >> 16) & 0xFF); // writing top 8 bits
    SPI.transfer ((data >> 8) & 0xFF); // writing middle 8 bits
    SPI.transfer (data & 0xFF); // writing bottom 8 bits    
    digitalWrite (SPISTE, HIGH); // disables device
}

uint32_t RegisterRead(uint8_t address)
{       
    uint32_t data=0;
    digitalWrite (SPISTE, LOW); // enables device
    SPI.transfer (address); // sends address to device
    data |= (SPI.transfer (0)<<16); // reading top 8 bits data
    data |= (SPI.transfer (0)<<8); // reading middle 8 bits  data
    data |= SPI.transfer (0); // reading bottom 8 bits data
    digitalWrite (SPISTE, HIGH); // disables device
    return data; // returns with 24 bits of read data
}

Console Output Below

Initializing

Initialization Complete.

1414
FFFF8002
4404


1414
FFFF8002
4404


1414
FFFF8002
4404

Thanks!

Any help or suggestions on this issue? thanks.

Mohammad,

Clearly 16 bits (lower 2 bytes) are being written and read correctly.

When register reads returns unsigned 32-bit data with MSB = 0, then where does the MSB 'FF' in "FFFF8002" come from?

Can you check the size of uint32_t? It seems like it is type defined to 16-bits.

Also capture the SPI waveforms on the oscilloscope and check if the SPI writes and reads are as expected.

Hello Praveen,

Thanks for your response.

sizeof(uint32_t)=4

Also, here are some screen caps of the output of my usb logic analyzer. I set the trigger on the rising edge of the clock.

Hello Mohammad,

Pleas let me know if you were able to resolve this issue.

Regards.

Praveen.

Hi Praveen,

Yes, it seems like I resolved it. For reading the registers properly, I had to send an additional dummy byte first in order to get the full 24 bits in return. I also ended up using the 'long' dataype instead.

Thanks.

Mohammad,

Good to know that you have resolved it.

If you have made the driver code working, please publish the basic driver code and its related documentation in the forum so that it will be useful to other community users who are also using the AFE44xx with the Arduino platform.

Best Regards.