Use timer interrupt for writing to display

3 files changed, 160 insertions, 39 deletions

diff --git a/src/display.c b/src/display.c
index 5f2d7f3..5fccd50 100644
--- a/src/display.c
+++ b/src/display.c
@@ -1,3 +1,4 @@
+#include <avr/interrupt.h>
 #include <avr/io.h>
 #include <stdint.h>
 #include <util/delay.h>
@@ -12,30 +13,63 @@ const uint32_t digit_masks[] = {
     0b00010010, 0b00000010, 0b01111000, 0b00000000, 0b00010000,
 };
 
+void setup_display() {
+  TIMSK1 = 0;
+
+  // Set prescaler (Timer clock = F_CPU / 64)
+  // For 32768Hz -> 32768/64 = 512Hz
+  TCCR1B = (1 << CS11) | (1 << CS10) | (1 << WGM12) | (1 << WGM13);
+  TCCR1A = (1 << WGM11) | (1 << WGM10);
+
+  TCNT1 = 0; // Start counting from 0
+  OCR1A = 1; // 0-1 = 2 counts before timer interrupt (512/2 = 256Hz)
+  OCR1B = 0;
+
+  TIFR1 = (1 << OCF1A) | (1 << OCF1B) | (1 << TOV1); // Clear interrupt flags
+  TIMSK1 = (1 << OCIE1A); // Enable timer overflow interrupt
+
+  // Draw startup state
+  DDRA |= 0b11111111;
+  DDRB |= 0b11111111;
+  PORTA = (1 << PA7);
+  PORTB = (1 << PB2);
+}
+
 void write_digit(uint8_t digit) {
   if (digit > 9 || digit < 0)
     return;
   PORTA = digit_masks[digit];
 }
 
-void write_time(uint16_t hour, uint16_t minute) {
+void write_time(uint16_t hour, uint16_t minute, uint8_t mask) {
   uint8_t minute_digit1 = minute % 10;
-  uint8_t minute_digit2 = minute / 10;
+  uint8_t minute_digit2 = (minute / 10) % 10;
   // unsigned short hour_digit1 = hour % 10;
-  // unsigned short hour_digit2 = hour / 10;
+  // unsigned short hour_digit2 = (hour / 10) % 10;
+
+  // _delay_ms(4);
+  // Reset digit control pins
+  PORTA &= ~(1 << PA7); // minute digit 1
+  PORTB &= ~(1 << PB2); // minute digit 2
+  // _delay_ms(4);
 
+  // cli();
+  if (mask & 0b0001 || mask & 0b0100) {
 #ifdef STUBBED
-  printf("\r:: %d %d", minute_digit2, minute_digit1);
-  fflush(stdout);
+    printf(":: %d\n", minute_digit1);
+    fflush(stdout);
 #endif
+    write_digit(minute_digit1);
+    PORTA |= (1 << PA7);
+  }
 
-  write_digit(minute_digit1);
-  PORTA |= (1 << PA7);
-  _delay_ms(10);
-  PORTA &= ~(1 << PA7);
-
-  write_digit(minute_digit2);
-  PORTB |= (1 << PB2);
-  _delay_ms(10);
-  PORTB &= ~(1 << PB2);
+  if (mask & 0b0010 || mask & 0b1000) {
+#ifdef STUBBED
+    printf(":: %d\n", minute_digit2);
+    fflush(stdout);
+#endif
+    write_digit(minute_digit2);
+    PORTB |= (1 << PB2);
+  }
+  // sei();
 }
diff --git a/src/display.h b/src/display.h
index a2bbc79..167374a 100644
--- a/src/display.h
+++ b/src/display.h
@@ -2,8 +2,10 @@
 #define _LOADED_DISPLAY
 #include <stdint.h>
 
+void setup_display();
+
 void write_digit(uint8_t digit);
 
-void write_time(uint16_t hour, uint16_t minute);
+void write_time(uint16_t hour, uint16_t minute, uint8_t digit_mask);
 
 #endif
diff --git a/src/main.c b/src/main.c
index fd4a091..b3fa431 100644
--- a/src/main.c
+++ b/src/main.c
@@ -1,45 +1,130 @@
+#include <avr/interrupt.h>
 #include <avr/io.h>
-#include <avr/fuse.h>
+#include <stdbool.h>
 #include <stdint.h>
 #include <util/delay.h>
 
 #include "display.h"
 
-// Config for attiny84a + 32KHz crystal osc taken from https://github.com/ingepnet/breadboardwatch/blob/master/Makefile#L26
+// Config for attiny84a + external 32KHz crystal osc taken from
+// https://github.com/ingepnet/breadboardwatch/blob/master/Makefile#L26
+#include <avr/fuse.h>
 FUSES = {
-  .low = 0xe6,
-  .high = 0xd7,
-  .extended = 0xff,
+    .low = 0xe6,
+    .high = 0xd7,
+    .extended = 0xff,
 };
 
-void setup_output(void) {
+void set_all_pins_output(void) {
   DDRA |= 0b11111111;
   DDRB |= 0b11111111;
 }
 
-int main(void) {
-  uint32_t count = 0;
-  uint8_t is_button_on = 0;
+void setup_rtc() {
+  // Set prescaler (Timer clock = F_CPU / 1024)
+  // For 32768Hz -> 32768/1024 = 32Hz
+  TCCR0B = (1 << CS02) | (1 << CS00) | (1 << WGM02);
+  TCCR0A = (1 << WGM01) | (1 << WGM00);
 
-  while (1) {
-    DDRB &= ~(1 << PB2);
-    is_button_on = (PINB & (1 << PB2)) > 0;
+  TCNT0 = 0;  // Start counting from 0
+  OCR0A = 31; // 0-31 = 32 counts before timer interrupt (1Hz)
+  OCR0B = 0;
+
+  // TIFR0 = (1 << TOV0);  // Clear interrupt flags
+  TIFR0 = (1 << OCF0A) | (1 << OCF0B) | (1 << TOV0); // Clear interrupt flags
+  // TIMSK0 = (1 << TOIE0); // Enable timer overflow interrupt
+  TIMSK0 = (1 << OCIE0A); // Enable timer overflow interrupt
+}
 
-    if (is_button_on) {
-      _delay_ms(30);
-      is_button_on = (PINB & (1 << PB2)) > 0;
-      if (is_button_on) {
-        setup_output();
-        PORTA |= 0b10000000;
-        _delay_ms(500);
-        continue;
-      }
+volatile uint8_t seconds = 10;
+volatile uint8_t minutes = 0;
+volatile uint8_t hours = 0;
+// Clock
+ISR(TIM0_COMPA_vect, ISR_FLATTEN) {
+  // if (true) {
+  //   OCR0A = 32;
+  // } else if (true) {
+  //   OCR0A = 31;
+  // } else {
+  //   OCR0A = 30;
+  // }
+
+  uint8_t s = seconds + 1;
+  seconds = s % 60;
+  if (s >= 60) {
+    uint8_t m = minutes + 1;
+    minutes = m % 60;
+    if (m >= 60) {
+      hours = (hours + 1) % 24;
     }
+  }
+}
+
+volatile static uint8_t digit_mask = 0b0001;
+// Display
+ISR(TIM1_COMPA_vect, ISR_FLATTEN) {
+  set_all_pins_output();
+  write_time(minutes, seconds, digit_mask);
+  if (seconds % 2) {
+    PORTA &= ~(1 << PA5);
+    PORTB &= ~(1 << PB3);
+  } else {
+    PORTA |= (1 << PA5);
+    PORTB |= (1 << PB3);
+  }
 
-    setup_output();
-    write_time(0, (count / 20) % 60);
+  digit_mask = digit_mask << 1;
+  if (digit_mask > 0b1000)
+    digit_mask = 0b0001;
+}
+
+#define IS_BUTTON_ON() ((PINA & (1 << PA0)) == 0)
+#define ENABLE_BUTTON() (DDRA &= ~(1 << PA0))
+
+int main(void) {
+  PRR = 0b0011; // Power reduction register. Shut down USI and ADC
+
+  setup_rtc();
+  setup_display();
+
+  sei();
 
-    count = (count + 1) % 100000;
+  set_all_pins_output();
+
+  while (1) {
+    // cli();
+    // set_all_pins_output();
+    // write_time(minutes, seconds, digit_mask);
+    // if (seconds % 2) {
+    //   PORTA &= ~(1 << PA5);
+    //   PORTB &= ~(1 << PB3);
+    // } else {
+    //   PORTA |= (1 << PA5);
+    //   PORTB |= (1 << PB3);
+    // }
+    // digit_mask = digit_mask << 1;
+    // if (digit_mask > 0b1000)
+    //   digit_mask = 0b0001;
+
+    // ENABLE_BUTTON();
+    // if (IS_BUTTON_ON()) {
+    //   cli();
+    //   ENABLE_BUTTON();
+    //   _delay_ms(25); // Debounced
+    //   if (IS_BUTTON_ON()) {
+    //     seconds += 1;
+    //     sei();
+    //     _delay_ms(50);
+    //     continue;
+    //   }
+    // }
+    // sei();
+
+#ifdef STUBBED
+    stub_run_timers();
+    _delay_ms(100);
+#endif
   }
+
   return 0;
 }