113 lines
3.6 KiB
C
113 lines
3.6 KiB
C
/* ----------------------------------------------------------------------------
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* Copyright (c) 2013 Ben Blazak <benblazak.dev@gmail.com>
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* Released under The MIT License (see "doc/licenses/MIT.md")
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* Project located at <https://github.com/benblazak/ergodox-firmware>
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* ------------------------------------------------------------------------- */
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/** description
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* Implements the timer interface defined in ".../firmware/lib/timer.h" for the
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* ATMega32U4
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*
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* See the accompanying '.md' file for further documentation.
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*
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* Notes:
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* - Not all of this code is device-specific, but the parts that aren't are
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* trivial enough that it's not worth separating them.
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*/
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#include <stdint.h>
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#include <avr/interrupt.h>
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#include <avr/io.h>
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#include "../../../../firmware/lib/data-types/list.h"
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#include "../event-list.h"
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// ----------------------------------------------------------------------------
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#if F_CPU != 16000000
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#error "Expecting different CPU frequency"
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#endif
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// ----------------------------------------------------------------------------
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/** variables/_cycles/description
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* The number of scan cycles since the timer was initialized (mod 2^16)
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*/
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static uint16_t _cycles;
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/** variables/_cycles__scheduled/description
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* A list of scheduled events, to be run in a given number of cycles
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*
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* After initialization, this should *only* be used as an argument to an
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* `event_list__...()` function.
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*/
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static list__list_t * _cycles__scheduled;
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/** variables/_milliseconds/description
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* The number of milliseconds since the timer was initialized (mod 2^16)
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*/
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static volatile uint16_t _milliseconds;
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/** variables/_milliseconds__scheduled/description
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* A list of scheduled events, to be run in a given number of milliseconds
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*
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* After initialization, this should *only* be used as an argument to an
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* `event_list__...()` function.
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*/
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static list__list_t * _milliseconds__scheduled;
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// ----------------------------------------------------------------------------
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uint8_t timer__init(void) {
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_cycles__scheduled = list__new();
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_milliseconds__scheduled = list__new();
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if (!_cycles__scheduled || !_milliseconds__scheduled) {
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list__free(_cycles__scheduled);
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list__free(_milliseconds__scheduled);
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return 1; // error
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}
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OCR0A = 250; // (ticks per millisecond)
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TCCR0A = 0b00000010; // (configure Timer/Counter 0)
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TCCR0B = 0b00000011; // (configure Timer/Counter 0)
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TIMSK0 = 0b00000010; // (enable interrupt vector)
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return 0; // success
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}
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uint16_t timer__get_cycles(void) {
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return _cycles;
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}
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uint16_t timer__get_milliseconds(void) {
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return _milliseconds;
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}
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uint8_t timer__schedule_cycles(uint16_t cycles, void(*function)(void)) {
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return event_list__append(_cycles__scheduled, cycles, function);
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}
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uint8_t timer__schedule_milliseconds( uint16_t milliseconds,
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void(*function)(void) ) {
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return event_list__append( _milliseconds__scheduled,
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milliseconds,
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function );
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}
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// ----------------------------------------------------------------------------
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void timer___tick_cycles (void) {
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_cycles++;
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event_list__tick(_cycles__scheduled);
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}
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// ----------------------------------------------------------------------------
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ISR(TIMER0_COMPA_vect) {
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_milliseconds++;
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event_list__tick(_milliseconds__scheduled);
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}
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