sampling.c

Z8 64k microcontroller code for sampling an input signal using built-in ADC

#include <eZ8.h>
#include <stdio.h>
#include <sio.h>

#define ENABLE 0x80             // CEN
#define SAMPLING_PRD 1440      // quarter-second sampling rate

#pragma interrupt
void isrTimer1(void) {
  ACTL |= ENABLE;               // start a single-shot conversion
}

#pragma interrupt
void isrADC(void) {
  int val;

  val = ((int)ADHR << 2) | (ADLR >> 6);
  printf("%4.3f \n", val/512.0);
}

void InitADC(void) {
  PBAF = 0x01;                  // PB0 = ANA0
  ACTL = 0x00;                  // ANA0, single, int VRef
}

void InitTimer(void) {
  DI();
  T1CTL = (0x07 << 3) | 0x01;   // Cont mode, prescale 2^7=128
  T1H = 0x00; T1L = 0x01;       // T1 start = 0x0001
  T1RH = (SAMPLING_PRD >> 8);   // T1 reload value
  T1RL = (SAMPLING_PRD & 0xFF);
  SET_VECTOR(TIMER1,isrTimer1);
  SET_VECTOR(ADC,isrADC);
  IRQ0ENH |= 0x41;              // high priority timer1 & ADC int
  IRQ0ENL |= 0x41;
  IRQ0 &= ~0x41;                // clr timer1 & ADC int flag
  EI();
  T1CTL |= 0x80;                // Enable timer1
}

void main(void) {
  init_uart(_UART0, _DEFFREQ, _DEFBAUD);
  printf("Press any key to start sampling\n");
  getch();
  InitADC();
  InitTimer();
}