diff options
Diffstat (limited to 'src/display.cc')
-rw-r--r-- | src/display.cc | 64 |
1 files changed, 64 insertions, 0 deletions
diff --git a/src/display.cc b/src/display.cc new file mode 100644 index 0000000..e06f271 --- /dev/null +++ b/src/display.cc @@ -0,0 +1,64 @@ +#include <avr/io.h> +#include <avr/interrupt.h> +#include <avr/wdt.h> +#include <util/delay.h> +#include <stdlib.h> + +#include "display.h" + +Display display; + +extern volatile uint8_t disp[8]; + +void Display::turn_off() +{ + TIMSK0 &= ~_BV(TOIE0); + PORTB = 0; + PORTD = 0; +} + +void Display::turn_on() +{ + TIMSK0 |= _BV(TOIE0); +} + +/* + * Draws a single display column. This function should be called at least once + * per millisecond. + * + * Current configuration: + * Called every 256 microseconds. The whole display is refreshed every 2048us, + * giving a refresh rate of ~500Hz + */ +ISR(TIMER0_OVF_vect) +{ + static uint8_t active_col = 0; + static uint16_t scroll = 0; + static uint8_t disp_offset = 0; + + static uint8_t disp_buf[8]; + + uint8_t i; + + if (++scroll == 512) { + scroll = 0; + if (++disp_offset == sizeof(disp)) { + disp_offset = 0; + } + + for (i = 0; i < 8; i++) { + disp_buf[i] = ~disp[(disp_offset + i) % sizeof(disp)]; + } + } + + /* + * To avoid flickering, do not put any code (or expensive index + * calculations) between the following three lines. + */ + PORTB = 0; + PORTD = disp_buf[active_col]; + PORTB = _BV(active_col); + + if (++active_col == 8) + active_col = 0; +} |