1 files changed, 81 insertions, 0 deletions
diff --git a/tuer-rfid/limits.c b/tuer-rfid/limits.c
new file mode 100644
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--- /dev/null
+++ b/tuer-rfid/limits.c
@@ -0,0 +1,81 @@
+/*
+ *  spreadspace avr utils
+ *
+ *
+ *  Copyright (C) 2013-2014 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/io.h>
+#include "limits.h"
+#include <LUFA/Drivers/Peripheral/ADC.h>
+
+#define LIMITS_ADC_CHAN_NUM 8
+#define LIMITS_ADC_CHAN ADC_CHANNEL8
+
+#define LIMITS_RINGBUF_SIZE 5
+/* HINT: this is compared to a sliding sum not an average! */
+#define LIMITS_TH_CLOSE 800
+#define LIMITS_TH_OPEN 2700
+
+void limits_init(void)
+{
+  ADC_Init(ADC_FREE_RUNNING | ADC_PRESCALE_128);
+  ADC_SetupChannel(LIMITS_ADC_CHAN_NUM);
+  ADC_StartReading(ADC_REFERENCE_AVCC | ADC_RIGHT_ADJUSTED | LIMITS_ADC_CHAN);
+}
+
+static uint16_t sum = 0;
+
+void limits_task(void)
+{
+  static uint16_t r[LIMITS_RINGBUF_SIZE] = { 0 };
+  static uint8_t idx = 0;
+
+  if(ADC_IsReadingComplete()) {
+    r[idx] = ADC_GetResult();
+    idx = (idx + 1) % LIMITS_RINGBUF_SIZE;
+    cli();
+    sum = 0;
+    uint8_t i;
+    for(i=0; i<LIMITS_RINGBUF_SIZE; ++i) sum += r[i];
+    sei();
+  }
+}
+
+limits_t limits_get(void)
+{
+  if(sum < LIMITS_TH_CLOSE)
+    return close;
+
+  if(sum < LIMITS_TH_OPEN)
+   return moving;
+
+  return open;
+}
+
+const char* limits_to_string(limits_t limits)
+{
+  switch(limits) {
+    case moving: return "...";
+    case open: return "opened";
+    case close: return "closed";
+    case both: return "error";
+  }
+  return "invalid"; // gcc - shut the fuck up!!!
+}