c lib for max6675 circuit

max6675.c

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "max6675.h"

max6675 device;

void iniciaMAX6675(volatile unsigned char *port, const char so_mask, const char sck_mask, const char cs_mask)
{
  device.SPI_PIN_PORT = (unsigned char*) port;

  device.SO_PIN_MASK = so_mask;
  device.SCK_PIN_MASK = sck_mask;
  device.CS_PIN_MASK = cs_mask;

  setNthBit (device.SPI_PIN_PORT, device.CS_PIN_MASK, 1);
  setNthBit (device.SPI_PIN_PORT, device.SCK_PIN_MASK, 0);  
}

unsigned int readSPIMAX6675 ()
{
  unsigned int retval = 0;
  
  setNthBit (device.SPI_PIN_PORT, device.CS_PIN_MASK, 0);
  
  for(int i = 0; i < 16; i++)
    {
       setNthBit (device.SPI_PIN_PORT, device.SCK_PIN_MASK, 1);       
       setNthBit (device.SPI_PIN_PORT, device.SCK_PIN_MASK, 0);       
    
       retval <<=1;
          if(isNthBitSet(device.SPI_PIN_PORT, device.SO_PIN_MASK))
            retval |= 1;
    }
  
    setNthBit (device.SPI_PIN_PORT, device.CS_PIN_MASK, 1);
    
  return (retval);
}

void readTempMAX6675 (float* temp)
{
  *temp = (readTwelveBits (readSPIMAX6675 ()) / 4); 
}

unsigned int readTwelveBits(unsigned int raw_value)
{
    return(0x0FFF & (raw_value>>3));
}

unsigned char isNthBitSet(unsigned char *c, unsigned char n)
{
  const unsigned char mask[] = {1, 2, 4, 8, 16, 32, 64, 128};
  return (*c & mask[n]);
}

void setNthBit(unsigned char *c, unsigned char n ,unsigned char b)
{ 
  if(b)
    *c |= 1 << n;
  else
    *c &= ~(1 << n);
}

max6675.h

/* 
 * File:   max6675.h
 * Author: eduardo
 *
 * Created on November 15, 2016, 8:11 AM
 */

#ifndef MAX6675_H
#define	MAX6675_H

#ifdef	__cplusplus
extern "C" {
#endif

#define setValue(value, mask) (value << mask)
    
    typedef struct _max6675{
        unsigned char * SPI_PIN_PORT;
        
        unsigned char  SO_PIN_MASK;
        unsigned char  SCK_PIN_MASK;
        unsigned char  CS_PIN_MASK;
    }max6675;
    
    void iniciaMAX6675(volatile unsigned char *port, const char so_mask, const char sck_mask, const char cs_mask);
    unsigned int readSPIMAX6675();
    void readTempMAX6675(float *temp);
    unsigned int readTwelveBits(unsigned int raw_value);
    unsigned char isNthBitSet(unsigned char *c, unsigned char n);
    void setNthBit(unsigned char *c, unsigned char n ,unsigned char b);
    void delay(int value);

#ifdef	__cplusplus
}
#endif

#endif	/* MAX6675_H */

This is a C library for reading via SPI (bit banging) the MAX6675 ADC integrated circuit.

Designed to be unlinked from hardware. Implementation in 3 lines of code. The library do not initialize pin direction
Example:
void main(){
float temp;
/*Function call passing PORT pins and numeration of the respective SO, SCK, CS*/
iniciaMAX6675 (&PORTA,0,1,2);
while(true){readTempMAX6675 (&temp);}
}