thermocouple/firmware/main.c

#include <avr/io.h>
#include <avr/interrupt.h>
#include <avr/pgmspace.h>
#include <avr/eeprom.h>
#include <util/delay.h>
#include <util/atomic.h>
#include <stdio.h>

#include <usbdrv/usbdrv.h>

#include "main.h"
#include "display.h"
#include "spi.h"


static uint8_t newThermoData = 1;
static uint16_t thermoData[] = {1024, 814, 2475, 2243};
volatile uint16_t timer1_acc;

#define SOFTTIMERNUMS 4
uint16_t softtimer_last[SOFTTIMERNUMS];

void softtimer_reset(uint8_t timernum){
    softtimer_last[SOFTTIMERNUMS] = timer1_acc;
}

uint8_t softtimer(uint8_t timernum, uint16_t interval){
    uint16_t timer1_acc_tmp = timer1_acc;  // because of volatile
    if((uint16_t)(timer1_acc_tmp - (uint16_t)(softtimer_last[timernum]) >= interval )){
        softtimer_last[timernum] = timer1_acc_tmp;
        return(1);
    }
    return(0);
}

#define SOFTTIMER(n,a) if(softtimer((n),(a*4)))





void hardinit() {
  /* initializes the hardware */
  DDRB = _BV(1) | _BV(2) | _BV(0);
  DDRC = 0x3f;

  // no pullups; all digital outputs can take care of themselves
  PORTB = 0x00;
  PORTC = 0x00;
  PORTD = 0x00;

  // hardware pwm for brightness/contrast:
  TCCR1A = _BV(COM1A1) | _BV(COM1B1) | _BV(WGM10);
  TCCR1B = _BV(WGM12) | _BV(CS11); // clk/8 prescaler, 4kHz PWM-freq.

  OCR1A = 15; // contrast
  OCR1B = 50; // brightness
	
  // init LCD:
  lcd_init(1);
  lcd_clrscr(1);

  sei();
}

void softinit() {
  lcd_defchar(1, LCD_CHAR_HALFBAR, lcd_halfbar_char);
  lcd_defchar(1, LCD_CHAR_BAR, lcd_bar_char);
  lcd_defchar(1, LCD_CHAR_DEGREE,  lcd_degree_char);
}

usbMsgLen_t usbFunctionSetup(uchar data[8]) {
  usbRequest_t    *rq = (void *)data;
  static uchar    dataBuffer[4];

  if(rq->bRequest == 1){
    dataBuffer[0] = (thermoData [0] & 0xff00)>>8;
    dataBuffer[1] = thermoData [0] & 0x00ff;
    dataBuffer[2] = (thermoData [1] & 0xff00)>>8;
    dataBuffer[3] = thermoData [1] & 0x00ff;
    usbMsgPtr = dataBuffer;
    return 4;
  }

  if(rq->bRequest == 2){
    dataBuffer[0] = (thermoData [2] & 0xff00)>>8;
    dataBuffer[1] = thermoData [2] & 0x00ff;
    dataBuffer[2] = (thermoData [3] & 0xff00)>>8;
    dataBuffer[3] = thermoData [3] & 0x00ff;
    usbMsgPtr = dataBuffer;
    return 4;
  }

  return 0;
}

void updateDisplay() {
  if(newThermoData==1) {
    newThermoData = 0;
    
    char str[34];
    snprintf(str, 34, "%3d.%02d\x03  %3d.%02d\x03\n%3d.%02d\x03  %3d.%02d\x03", thermoData[0]/100, thermoData[0]%100,
	     thermoData[1]/100, thermoData[1]%100,
	     thermoData[2]/100, thermoData[2]%100,
	     thermoData[3]/100, thermoData[3]%100
	   );
    display_gotoyx(0,0);
    display_puts(str);
    display_update();
  }
}

int __attribute__((noreturn)) main(void) {
  int i=0;
  hardinit();
  softinit();
  usbInit();

  display_puts("Hallo, Welt!\n\n");
  display_update();

  
  for(;;){
    usbPoll();

    SOFTTIMER(1,100){
        updateDisplay();
    }

    thermoData[0]=thermoData[0]+5;
    thermoData[1]=thermoData[1]+15;
    thermoData[2]=thermoData[2]+7;
    thermoData[3]=thermoData[3]+18;
    i++; if(i%200 == 0) newThermoData = 1;
  }
}

/*
  ISR(TIMER1_OVF_vect, ISR_NAKED){
  asm volatile ("in %0, %1\n" : "=r" (sreg_store) : "I" (_SFR_IO_ADDR(SREG)));
  timer1_acc++;
  asm volatile ("out %1, %0\n" : "=r" (sreg_store) : "I" (_SFR_IO_ADDR(SREG)));
  reti();
  }*/
ISR(TIMER1_OVF_vect,ISR_NOBLOCK){
    uint16_t temp;
    temp=timer1_acc;
    temp++;
    ATOMIC_BLOCK(ATOMIC_FORCEON){ 
        timer1_acc=temp;
    }
    /* the ATOMIC is acutally only needed if timer1_acc is never read from an ISR, which
     * is probably the case.
     * ATOMIC_FORCEON: the ISR_NOBLOCK sets sei() a few cycles before.
     */
}