B4R Question SPI Library

Sub Process_Globals
    'These global variables will be declared once when the application starts.
    'Public variables can be accessed from all modules.
    Public Serial1 As Serial
    Private D1 As D1Pins
    Private SCK As Pin
    Private SS As Pin
    Private MISO As Pin
'   
End Sub

Private Sub AppStart
    Serial1.Initialize(115200)
    Log("AppStart")
'   
    SCK.Initialize(D1.D5, SCK.MODE_OUTPUT)
    SS.Initialize(D1.D8, SS.MODE_OUTPUT)
    MISO.Initialize(D1.D6, MISO.MODE_INPUT)
    AddLooper("Looper1")
End Sub

Sub looper1
    SPI.adcSingleChannelRead(SS,??)
End Sub

/*
pins:
 cs=8
 sdo/rdy=12
 sck=13
*/

#include <SPI.h>

unsigned char sspin=8; //cs pin

union{
        int32_t value;
        uint8_t aa[4];
    } c ;
    

void setup(void){
pinMode(12,INPUT);  //to check ready pin
pinMode(sspin,OUTPUT);
digitalWrite(sspin,HIGH);//for single conversion
SPI.begin();
SPI.setBitOrder(MSBFIRST);
SPI.setDataMode(SPI_MODE3);
SPI.setClockDivider(SPI_CLOCK_DIV16);//max. speed of chip is 5 Mhz
Serial.begin(9600); 

}

void loop(void){
 
digitalWrite(sspin,LOW);

while(digitalRead(12)){
 
  digitalWrite(sspin,LOW);
                    
                    }
c.aa[2]=SPI.transfer(0x00);
c.aa[1]=SPI.transfer(0x00);
c.aa[0]=SPI.transfer(0x00);
c.aa[3]=0x00;
digitalWrite(sspin,HIGH);
//check if overflow has occured
if((c.aa[2]&(1<<6))|(c.aa[2]&(1<<7))){
  c.aa[2]&=~(1<<6);
  Serial.println(c.value);
}
//check if sign bit is affected. if so, since it is two's compliment,
// substract it from 2^N
else if(c.aa[2]&(1<<5)){
c.value=0x400000-c.value;
Serial.println(c.value);
}

else{
Serial.println(c.value);
}
  delay(10);

}

Public Sub MCP3551Read(clckSpeed As Int, chipSelectPin As Pin) As Long
    chipSelectPin.DigitalWrite(True)
    BeginTransaction(clckSpeed,MSBFIRST,SPI_MODE(3))
    chipSelectPin.DigitalWrite(False)
    Dim b(4) As Byte
    b(2) = Transfer(0x00)
    b(1) = Transfer(0x00)
    b(0) = Transfer(0x00)
    b(3) = 0x00
    chipSelectPin.DigitalWrite(True)
    Dim res As Long = 0
    EndTransaction
    Dim r As RandomAccessFile
    If UintToBoolean( Bit.Or( Bit.And(b(2),Bit.ShiftLeft(1,6)), Bit.And(b(2),Bit.ShiftLeft(1,7)) )) Then
        b(2) = Bit.And(b(2),Bit.Not(Bit.ShiftLeft(1,6)))
        Dim r As RandomAccessFile
        r.Initialize(b,True)
        res = r.ReadLong32(0)
    Else if UintToBoolean(Bit.And(b(2),Bit.ShiftLeft(1,5))) Then
        r.Initialize(b,True)
        res = r.ReadLong32(0)
        res = 0x400000-res
    End If
    Return res
End Sub

Public Sub UintToBoolean(u As UInt) As Boolean
    Return u<>0
End Sub