52 lines
1.5 KiB
C
52 lines
1.5 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 device specific portion of the timer interface defined in
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* ".../firmware/lib/timer.h" for the 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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#include <stdint.h>
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#include <avr/interrupt.h>
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#include <avr/io.h>
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#include "../../timer.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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static struct {
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volatile uint16_t counter;
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} milliseconds;
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// ----------------------------------------------------------------------------
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uint8_t timer__init(void) {
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OCR0A = 250; // (ticks (of hardware timer) 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_milliseconds(void) {
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return milliseconds.counter;
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}
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ISR(TIMER0_COMPA_vect) {
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milliseconds.counter++;
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}
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