1 files changed, 105 insertions, 0 deletions
diff --git a/controller.c b/controller.c
new file mode 100644
index 0000000..29ac0ab
--- /dev/null
+++ b/controller.c
@@ -0,0 +1,105 @@
+#include <avr/io.h>
+#include <avr/interrupt.h>
+
+#include "controller.h"
+
+#include "bridge.h"
+
+static void adc_init(void)
+{
+	/* Configure the ADC */
+	ADMUX = (1 << REFS1) | (1 << REFS0);
+	/* select channel x (0 for now) */
+	ADMUX |= 0x0;
+	ADCSRA = (1 << ADEN) | (1 << ADIE)
+		| (1 << ADPS2) | (1 << ADPS1)
+		| (1 << ADPS0);
+}
+
+/* Initializes TIMER1 */
+static void timer_init(void)
+{
+	TCCR1B = (1 << WGM12) | (1 << CS12) | (1 << CS10);
+	OCR1A = 7200;
+	TIMSK|=(1<<OCIE1A);
+}
+
+static volatile char controller_in_init;
+static volatile char controller_active;
+static volatile long controller_target_temp;
+static volatile char controller_num_iterations;
+static volatile uint16_t controller_measured_temp;
+
+void controller_init(void)
+{
+	controller_active = 0;
+	controller_in_init = 1;
+
+	bridge_init();
+	adc_init();
+	timer_init();
+}
+
+int controller_set(long target)
+{
+	if (target < 50 || target > 974)
+		return 1;
+
+	controller_target_temp = target;
+	controller_num_iterations = 1;
+	controller_active = 1;
+	return 0;
+}
+
+long controller_get(void)
+{
+	return controller_measured_temp;
+}
+
+void controller_off(void)
+{
+	controller_active = 0;
+	bridge_off();
+}
+
+ISR(TIMER1_COMPA_vect)
+{
+	/* Start adc measurement */
+	ADCSRA |= (1<<ADSC);
+}
+
+ISR(ADC_vect) 
+{
+	if (controller_in_init) {
+		controller_measured_temp = ADCW;
+		controller_in_init = 0;
+	} else {
+		controller_measured_temp = (0.8 * controller_measured_temp)
+			                 + (0.2 * ADCW);
+	}
+
+	if (! controller_active)
+		return;
+
+	controller_num_iterations--;
+	if (controller_num_iterations)
+		return;
+
+	controller_num_iterations = 60;
+
+	if ((long)controller_measured_temp < controller_target_temp - 20) {
+		/* Cooling required */
+		bridge_on_cool();
+		return;
+	}
+
+	if ((long)controller_measured_temp > controller_target_temp + 20) {
+		/* Heating required */
+		bridge_on_heat();
+		return;
+	}
+
+	/* Temperature is roughly okay, turn bridge off until next
+	 * measurement. */
+	bridge_off();
+}