一个低成本的低功耗时钟项目

void PortSetup () {  for (int p=0; p<4; p++) Digit[p]->DIR = 0xFF;       // All pins outputs  PORTE.DIR = PIN0_bm | PIN1_bm;                      // COMs outputs, PE0 and PE1  PORTF.DIR = PIN5_bm | PIN4_bm;                      // 1A, colon}

ISR(RTC_PIT_vect) {  static uint8_t cycles = 0;  static unsigned long halfsecs;  RTC.PITINTFLAGS = RTC_PI_bm;                        // Clear interrupt flag  // Toggle segments  for (int p=0; p<4; p++) Digit[p]->OUTTGL = 0xFF;    // Toggle all PORTA,B,C,D pins  PORTE.OUTTGL = PIN0_bm | PIN1_bm;                   // Toggle COMs, PE0 and PE1  PORTF.OUTTGL = PIN5_bm | PIN4_bm;                   // Toggle segment 1A, Colon
  cycles++;  if (cycles < 32) return;  cycles = 0;
  // Update time  halfsecs = (halfsecs+1) % 172800;                   // 24 hours  uint8_t ticks = halfsecs % 120;                     // Half-second ticks                   if (MinsButton()) halfsecs = ((halfsecs/7200)*60 + (halfsecs/120 + 1)%60)*120;  if (HoursButton()) halfsecs = halfsecs + 7200;
  if (MinsButton() || HoursButton() || ticks < 108) DisplayTime(halfsecs);  else if (ticks == 108) DisplayVoltage();  else if (ticks == 114) DisplayTemp();}

void DisplayTime (unsigned long halfsecs) {  uint8_t minutes = (halfsecs / 120) % 60;  #ifdef TWELVEHOUR  uint8_t hours = (halfsecs / 7200) % 12 + 1;  #else  uint8_t hours = (halfsecs / 7200) % 24;  #endif  Digit[0]->OUT = Char[hours/10];  Digit[1]->OUT = Char[hours%10];  Digit[2]->OUT = Char[minutes/10];  uint8_t units = Char[minutes%10];  Digit[3]->OUT = units;  uint8_t colon = (halfsecs & 1)<<4;                  // Toggle colon at 1Hz     PORTF.OUT = (units>>1 & PIN5_bm) | colon;}

void DisplayVoltage () {  ADC0.MUXPOS = ADC_MUXPOS_DACREF0_gc;                // Measure DACREF0  ADC0.CTRLA = ADC_ENABLE_bm;                         // Single, 12-bit, left adjusted  ADC0.COMMAND = ADC_STCONV_bm;                       // Start conversion  while (ADC0.COMMAND & ADC_STCONV_bm);               // Wait for completion  uint16_t adc_reading = ADC0.RES;                    // ADC conversion result  uint16_t voltage = adc_reading/50;  ADC0.CTRLA = 0;                                     // Disable ADC
  // Display it  Digit[0]->OUT = Char[Space];  Digit[1]->OUT = Char[voltage/10] | 0x80;            // Decimal point  Digit[2]->OUT = Char[voltage%10];  uint8_t units = Char[Vee];  Digit[3]->OUT = units;  PORTF.OUT = (units>>1 & PIN5_bm);                   // No colon}