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Diffstat (limited to 'usb-i2c-sl018/heartbeat.c')
-rw-r--r-- | usb-i2c-sl018/heartbeat.c | 68 |
1 files changed, 68 insertions, 0 deletions
diff --git a/usb-i2c-sl018/heartbeat.c b/usb-i2c-sl018/heartbeat.c new file mode 100644 index 0000000..6822320 --- /dev/null +++ b/usb-i2c-sl018/heartbeat.c @@ -0,0 +1,68 @@ +/* + * spreadspace avr utils + * + * + * Copyright (C) 2013 Christian Pointner <equinox@spreadspace.org> + * Othmar Gsenger <otti@wirdorange.org> + * + * This file is part of spreadspace avr utils. + * + * spreadspace avr utils is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * any later version. + * + * spreadspace avr utils is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with spreadspace avr utils. If not, see <http://www.gnu.org/licenses/>. + */ + +#include <avr/sfr_defs.h> +#include <avr/interrupt.h> + +#include "led.h" +#include "heartbeat.h" + +#define HEARTBEAT_DURATION 10 // *10 ms, duration of heartbeat pulse +#define HEARTBEAT_DELAY 200 // *10 ms, 1/heartbeat-frequency +uint8_t heartbeat_cnt = 0; +uint8_t heartbeat_flag; + +// while running this gets called every ~10ms +ISR(TIMER0_COMPA_vect) +{ + heartbeat_cnt++; + if(heartbeat_cnt == HEARTBEAT_DURATION) + heartbeat_flag = 0; + else if(heartbeat_cnt >= HEARTBEAT_DELAY) { + heartbeat_flag = 1; + heartbeat_cnt = 0; + } +} + +void init_heartbeat(void) +{ + led_off(); + heartbeat_cnt = 0; + heartbeat_flag = 1; + + // timer 2: ~10 ms, timebase for heartbeat signal + TCCR0A = 1<<WGM01; // OC0A and OC0B as normal output, WGM = 2 (CTC) + TCCR0B = 1<<CS02 | 1<<CS00; // Prescaler 1:1024 + OCR0A = 155; // (1+155)*1024 = 159744 -> ~10 ms @ 16 MHz + //OCR2A = 194; // (1+194)*1024 = 199680 -> ~10 ms @ 20 MHz + TCNT2 = 0; // reseting timer + TIMSK0 = 1<<OCIE0A; // enable Interrupt +} + +void handle_heartbeat(void) +{ + if(heartbeat_flag) + led_on(); + else + led_off(); +} |