1 files changed, 93 insertions, 0 deletions
diff --git a/table-fan/fan.c b/table-fan/fan.c
new file mode 100644
index 0000000..daa33f4
--- /dev/null
+++ b/table-fan/fan.c
@@ -0,0 +1,93 @@
+/*
+ *  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 <stdio.h>
+
+
+#define PWM_VAL_MAX 160
+
+void fan_init(void)
+{
+      // timer for tacho
+  DDRD &= ~(1<<PD4);
+  PORTD |= (1<<PD4);
+  TCCR1B = 0; // make sure timer is stopped
+
+  TCCR1A = 0;
+  TCNT1 = 0;
+  TIMSK1 = (1<<ICIE1);
+
+  TCCR1B = (1<<CS12); // start timer
+
+      // PWM for speed control
+  DDRB |= (1<<PB6);
+  TCCR4B = 0; // make sure timer is stopped
+
+  TCCR4A = (1<<COM4B1) | (1<<PWM4B);
+  TCCR4D = (1<<WGM40);
+  TCNT4 = 0;
+  OCR4C = PWM_VAL_MAX;
+
+  OCR4B = PWM_VAL_MAX/2; // set duty cycle to 50:50
+  TCCR4B = (1<<CS41); // start timer
+}
+
+void fan_speed_set(uint8_t val)
+{
+  OCR4B = (val > PWM_VAL_MAX) ? PWM_VAL_MAX : val;
+}
+
+uint8_t fan_speed_get(void)
+{
+  return OCR4B;
+}
+
+void fan_speed_inc(void)
+{
+  if(OCR4B < PWM_VAL_MAX)
+    OCR4B++;
+}
+
+void fan_speed_dec(void)
+{
+  if(OCR4B > 0)
+    OCR4B--;
+}
+
+ISR(TIMER1_CAPT_vect)
+{
+  static uint16_t tacho_last_ts = 0;
+  uint16_t current = ICR1;
+  uint16_t diff = 0;
+  if(current > tacho_last_ts) {
+    diff = current - tacho_last_ts;
+  } else {
+    diff = (UINT16_MAX - tacho_last_ts) + current;
+  }
+  tacho_last_ts = current;
+
+  uint16_t rpm = 1875000 / diff;
+  printf("\rspeed: %6d rpm", rpm);
+}