1 files changed, 82 insertions, 0 deletions
diff --git a/table-fan/rotary.c b/table-fan/rotary.c
new file mode 100644
index 0000000..beb95c1
--- /dev/null
+++ b/table-fan/rotary.c
@@ -0,0 +1,82 @@
+/*
+ *  spreadspace avr utils
+ *
+ *
+ *  Copyright (C) 2021 Christian Pointner <equinox@spreadspace.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 <avr/interrupt.h>
+
+#include "rotary.h"
+
+#define DEBOUNCE_MAX 100
+uint8_t last_stable = 0;
+
+static inline uint8_t get_current(void)
+{
+  return (PINB & ((1<<PB4) | (1<<PB5))) >> PB4;
+}
+
+void rotary_init(void)
+{
+  DDRB &= ~((1<<PB4) | (1<<PB5));
+  PORTB |= (1<<PB4) | (1<<PB5);
+  last_stable = get_current();
+}
+
+rotary_dir_t rotary_task(void)
+{
+  static uint8_t last = 0;
+  static uint8_t cnt = 0;
+
+  uint8_t current = get_current();
+  if(last == current)
+    cnt += (cnt < DEBOUNCE_MAX) ? 1 : 0;
+  else
+    cnt -= (cnt > 0) ? 1 : 0;
+  last = current;
+
+  if(cnt < DEBOUNCE_MAX)
+    return rotary_dir_none;
+  cnt = 0;
+
+  rotary_dir_t dir = rotary_dir_none;
+  if(last_stable != current) {
+    switch(last_stable) {
+    case 0:
+      if(current == 1) dir = rotary_dir_up;
+      if(current == 2) dir = rotary_dir_down;
+      break;
+    case 1:
+      if(current == 3) dir = rotary_dir_up;
+      if(current == 0) dir = rotary_dir_down;
+      break;
+    case 2:
+      if(current == 0) dir = rotary_dir_up;
+      if(current == 3) dir = rotary_dir_down;
+      break;
+    case 3:
+      if(current == 2) dir = rotary_dir_up;
+      if(current == 1) dir = rotary_dir_down;
+      break;
+    }
+  }
+  last_stable = current;
+  return dir;
+}