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- #include <avr/io.h>
- #include <avr/interrupt.h>
- #include <stdint.h>
- #include "timer.h"
-
- 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;
- TCCR0B = 0x05;
- TIMSK0 = (1<<TOIE0);
- }
-
- inline
- void timer_clear(void)
- {
- uint8_t sreg = SREG;
- cli();
- timer_count = 0;
- SREG = sreg;
- }
-
- inline
- uint16_t timer_read(void)
- {
- uint16_t t;
-
- uint8_t sreg = SREG;
- cli();
- t = timer_count;
- SREG = sreg;
-
- return t;
- }
-
- inline
- uint16_t timer_elapsed(uint16_t last)
- {
- uint16_t t;
-
- uint8_t sreg = SREG;
- cli();
- t = timer_count;
- SREG = sreg;
-
- return TIMER_DIFF(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)
- {
- timer_count++;
- }
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