Hey, all!
I am currently making a pulse oximetre that use arduino pro 328 (3.3V,8 MHz) with texas instrument's Analogue Front End chip AFE4490.
I am a problem with its SPI communication. So, when i plug the MOSI from arduino to the chip, it results nothing. But, when I unplug it, it results random number. So I concluded from that, I have no problem with the hardware.
But, I am confused why it still results zero, despite of input is available. I am suspecting there is something wrong with my code.
I am not good with finding error myself, perhaps, anyone here knows where is the problem from my following code?
#include <intrinsics.h>
#include <string.h>
#include "AFE4490.h"
#include <SPI.h>
/* Arduino Mega
//SPI connection
const int SOMI = 50; //data out connect to MISO
const int SIMO = 51; //data in connect to MOSI //butuh logic level converter
const int SCLK = 52;
const int SPISTE = 53; //butuh logic level converter
const int CLKOUT = 47;
const int AFEADCRDY = 48; //butuh logic l
evel converter
const int AFEPDNZ = 49;
*/
const int SOMI = 16; //data out connect to MISO
const int SIMO = 15; //data in connect to MOSI //butuh logic level converter
const int SCLK = 17;
const int SPISTE = 14; //butuh logic level converter
int count = 0;
//function declarations
//void AFE4490EnableInterrupt (void);
//void AFE4490DisableInterrupt (void);
void AFE4490Write (uint8_t address, uint32_t data);
uint32_t AFE4490Read (uint8_t address);
void SPIInit (void);
void setup()
{
Serial.begin(9600);
pinMode (SOMI,INPUT);
pinMode (SPISTE,OUTPUT);
pinMode (SCLK, INPUT);
pinMode (SIMO, OUTPUT);
//pinMode (CLKOUT, INPUT);
//pinMode (AFEADCRDY, OUTPUT);
//pinMode (AFEPDNZ, OUTPUT);
//digitalWrite (SPISTE, HIGH);
//digitalWrite (SCLK,HIGH);
//digitalWrite (SIMO, 0X00000000);
//digitalWrite (AFEPDNZ, HIGH);
AFE4490Init ();
//AFE4490DisableInterrupt();
for (int count= 0; count<60; count++)
{
Serial.println(count);
delay (1000);
Serial.print("Red Data:");
Serial.println(AFE4490Read(LED2VAL));
Serial.print("Red Ambient Data:");
Serial.println(AFE4490Read(ALED2VAL));
Serial.print("Red Different:");
Serial.println(AFE4490Read(LED2ABSVAL));
Serial.print("IR Data:");
Serial.println(AFE4490Read(LED1VAL));
Serial.print("IR Ambient:");
Serial.println(AFE4490Read(ALED1VAL));
Serial.print("IR Different:");
Serial.println(AFE4490Read(LED1ABSVAL));
}
//AFE4490EnableInterrupt ();
}
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////
void loop()
{
delay (1000);
}
/*
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////
void AFE4490EnableInterrupt (void)
{
digitalWrite(AFEADCRDY, HIGH);
}
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////
void AFE4490DisableInterrupt (void)
{
digitalWrite(AFEADCRDY,LOW);
}
*/
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////
void AFE4490Init (void)
{
Serial.println("AFE4490 Initialization Starts");
AFE4490Write(CONTROL0, 0x000000);
AFE4490Write(CONTROL1, 0x000101);
AFE4490Write(CONTROL2, 0x000000); // Disable crystal, we supply 8MHz directly
AFE4490Write(PRPCOUNT, 0X001F3F);
AFE4490Write(LED2STC, 0X001770); //timer control
AFE4490Write(LED2ENDC,0X001F3E); //timer control
AFE4490Write(LED2LEDSTC,0X001770); //timer control
AFE4490Write(LED2LEDENDC,0X001F3F); //timer control
AFE4490Write(ALED2STC, 0X000000); //timer control
AFE4490Write(ALED2ENDC, 0X0007CE); //timer control
AFE4490Write(LED2CONVST,0X000002); //timer control
AFE4490Write(LED2CONVEND, 0X0007CF); //timer control
AFE4490Write(ALED2CONVST, 0X0007D2); //timer control
AFE4490Write(ALED2CONVEND,0X000F9F); //timer control
AFE4490Write(LED1STC, 0X0007D0); //timer control
AFE4490Write(LED1ENDC, 0X000F9E); //timer control
AFE4490Write(LED1LEDSTC, 0X0007D0); //timer control
AFE4490Write(LED1LEDENDC, 0X000F9F); //timer control
AFE4490Write(ALED1STC, 0X000FA0); //timer control
AFE4490Write(ALED1ENDC, 0X00176E); //timer control
AFE4490Write(LED1CONVST, 0X000FA2); //timer control
AFE4490Write(LED1CONVEND, 0X00176F); //timer control
AFE4490Write(ALED1CONVST, 0X001772); //timer control
AFE4490Write(ALED1CONVEND, 0X001F3F); //timer control
AFE4490Write(ADCRSTCNT0, 0X000000); //timer control
AFE4490Write(ADCRSTENDCT0,0X000000); //timer control
AFE4490Write(ADCRSTCNT1, 0X0007D0); //timer control
AFE4490Write(ADCRSTENDCT1, 0X0007D0); //timer control
AFE4490Write(ADCRSTCNT2, 0X000FA0); //timer control
AFE4490Write(ADCRSTENDCT2, 0X000FA0); //timer control
AFE4490Write(ADCRSTCNT3, 0X001770); //timer control
AFE4490Write(ADCRSTENDCT3, 0X001770);
AFE4490Write(CONTROL2,0x020200); // Disable crystal, 0.5V TX_REF
AFE4490Write(LEDCNTRL,0x008080); // LED_RANGE=100mA, LED=50mA
AFE4490Write(CONTROL1,0x000103); // Timers ON, average 3 samples
AFE4490Write(CONTROL0,0x000001); // Switch to READ mode
delay(1000);
Serial.println("AFE4490 Initialization Done");
}
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////
void SPIInit (void)
{
SPI.setClockDivider (SPI_CLOCK_DIV128);
SPI.setDataMode (SPI_MODE0);
}
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////
void AFE4490Write (uint8_t address, uint32_t data)
{
if (digitalRead (SOMI) == HIGH)
{
Serial.println ("SOMI pin is connected!Writing register is proceeded!");
SPIInit();
SPI.begin();
digitalWrite (SPISTE, LOW);
SPI.transfer (address);
Serial.println (address);
SPI.transfer ((data>>16)&0XFF);
Serial.println ((data>>16)&0XFF);
SPI.transfer ((data>>8)&0XFF);
Serial.println ((data>>8)&0XFF);
SPI.transfer (data &0XFF);
Serial.println (data &0XFF);
digitalWrite (SPISTE, HIGH);
Serial.println("Writing Register Succeded!");
SPI.end();
}
else
{
Serial.println ("SOMI is not connected, please check the wire!");
}
}
/////////////////////////////////////////////////////////////////////////////////////////////////////////////////
uint32_t AFE4490Read (uint8_t address)
{
SPIInit();
uint32_t data = 0;
digitalWrite (SPISTE, LOW);
SPI.begin();
SPI.transfer (address);
Serial.print (address);
Serial.print (" ");
data |= (SPI.transfer (0) <<16);
Serial.print (data,BIN);
Serial.print (" ");
data |= (SPI.transfer (0) <<8);
Serial.print (data,BIN);
Serial.print (" ");
data |= SPI.transfer (0);
Serial.print (data,BIN);
Serial.print (" ");
digitalWrite (SPISTE, HIGH);
SPI.end();
return data;
}
Special thanks for Krupski, on helping me with the Read and Writing register 
Best Regards,
Stella