speaker: Initial implementation

1 files changed, 49 insertions, 0 deletions

diff --git a/speaker.c b/speaker.c
new file mode 100644
index 0000000..d903c57
--- /dev/null
+++ b/speaker.c
@@ -0,0 +1,49 @@
+/*	speaker control, uses timer2
+ */
+
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <stdbool.h>
+
+#include "speaker.h"
+
+static bool value = false;
+
+static void speakerSet () {
+	if (value) {
+		PORTD = PORTD | (1 << PD6);
+	} else {
+		PORTD = PORTD & ~(1 << PD6);
+	}
+}
+
+ISR(TIMER2_OVF_vect) {
+	value = !value;
+	speakerSet ();
+}
+
+void speakerInit () {
+	/* set PD6 to output */
+	DDRD |= (1 << PD6);
+	/* value is false */
+	speakerSet ();
+}
+
+void speakerStart () {
+	/* reset timer value */
+	TCNT2 = 0;
+	/* set normal mode timer0 */
+	TCCR2A = 0;
+	/* enable overflow interrupt */
+	TIMSK2 = (1 << TOIE2);
+	/* io clock with 1024 prescaler */
+	TCCR2B = (TCCR2B & ~((1 << CS21)) | (1 << CS22) | (1 << CS20));
+}
+
+void speakerStop () {
+	/* zero clock source */
+	TCCR2B = 0;
+	value = false;
+	speakerSet ();
+}
+