From 9aa0db689fdd927433f61087eab1d30fb9f7133d Mon Sep 17 00:00:00 2001
From: Christian Pointner <equinox@spreadspace.org>
Date: Tue, 5 Feb 2013 01:37:22 +0000
Subject: added heartbeat

git-svn-id: https://svn.spreadspace.org/avr/trunk@116 aa12f405-d877-488e-9caf-2d797e2a1cc7
---
 usb-i2c-sl018/heartbeat.c | 68 +++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 68 insertions(+)
 create mode 100644 usb-i2c-sl018/heartbeat.c

(limited to 'usb-i2c-sl018/heartbeat.c')

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();
+}
-- 
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