Use timer interrupt for writing to display

1 files changed, 48 insertions, 14 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();
 }