adc.c

nordic semiconductor

/*= adc.c =====================================================================
 *
 * Written by  Greg Hunter, University of Technology, Sydney, 2007 for sdcc compiler
 * See adc.h for details
 *
 *==============================================================================
*/

#include "regs24e1.h"
#include "adc.h"
#include "delay.h"

//********************************************************
// AdcInit
//  Initialise analog to digital converter
//  Converter is left in 10 bit mode, with channel 0 connected
//   and ready to start conversion.
//********************************************************
void AdcInit(void)
{
  ADCCON = 0X20;    // Channel 0, NDP = 1 (Power ON), ADCRUN = 0, EXTREF = 0 (internal reference of 1.22V)
  EXIF &= ~0x10;    // Clear end of conversion flag
}

//********************************************************
// AdcRead
//  Read adc using channel parameter, returning read value
//********************************************************
unsigned int AdcRead(unsigned char channel)
{
  unsigned int i;
//set channel
  ADCCON = 0x20 + channel;
//delay 5u
  Delay5us();
//start conversion
  ADCCON |= 0X80;
//delay 5u
  Delay5us();
//wait for end of conversion
  while((EXIF & 0X10) == 0) ;
//Clear end of conversion flag
  EXIF &= ~0x10;               
//read data
  i = (ADCDATAL & 0xC0) + (((unsigned int) ADCDATAH)<<8);
  return i;
}