diff options
Diffstat (limited to 'timer.c')
| -rw-r--r-- | timer.c | 35 |
1 files changed, 23 insertions, 12 deletions
@@ -20,17 +20,31 @@ along with this program. If not, see <http://www.gnu.org/licenses/>. #include <stdint.h> #include "timer.h" + +// counter resolution 1ms volatile uint16_t timer_count = 0; -// Configure timer 0 to generate a timer overflow interrupt every -// 256*1024 clock cycles, or approx 61 Hz when using 16 MHz clock -// This demonstrates how to use interrupts to implement a simple -// inactivity timeout. void timer_init(void) { - TCCR0A = 0x00; + // Timer0 CTC mode + TCCR0A = 0x02; + +#if TIMER_PRESCALER == 1 + TCCR0B = 0x01; +#elif TIMER_PRESCALER == 8 + TCCR0B = 0x02; +#elif TIMER_PRESCALER == 64 + TCCR0B = 0x03; +#elif TIMER_PRESCALER == 256 + TCCR0B = 0x04; +#elif TIMER_PRESCALER == 1024 TCCR0B = 0x05; - TIMSK0 = (1<<TOIE0); +#else +# error "Timer prescaler value is NOT vaild." +#endif + + OCR0A = TIMER_RAW_TOP; + TIMSK0 = (1<<OCIE0A); } inline @@ -65,14 +79,11 @@ uint16_t timer_elapsed(uint16_t last) t = timer_count; SREG = sreg; - return TIMER_DIFF(t, last); + return TIMER_DIFF_MS(t, last); } -// This interrupt routine is run approx 61 times per second. -// A very simple inactivity timeout is implemented, where we -// will send a space character and print a message to the -// hid_listen debug message window. -ISR(TIMER0_OVF_vect) +// excecuted once per 1ms.(excess for just timer count?) +ISR(TIMER0_COMPA_vect) { timer_count++; } |