1 files changed, 69 insertions, 0 deletions
diff --git a/ferment.c b/ferment.c
new file mode 100644
index 0000000..aba1916
--- /dev/null
+++ b/ferment.c
@@ -0,0 +1,69 @@
+#define F_CPU 1000000UL
+#include <stdint.h>
+#include <string.h>
+#include <avr/io.h>
+#include <avr/interrupt.h>
+#include <avr/sleep.h>
+#include <avr/pgmspace.h>
+#include <avr/eeprom.h>
+#include <util/delay.h>
+
+/* port D
+ *
+ *  4 1- (NMOS, inverted) 
+ *  5 1+ (PMOS)
+ *  6 2- (NMOS, inverted)
+ *  7 2+ (PMOS)
+ *
+ */
+
+#define D_1_MINUS	(1 << 4)
+#define D_1_PLUS	(1 << 5)
+#define D_2_MINUS	(1 << 6)
+#define D_2_PLUS	(1 << 7)
+
+/* Turns the H-bridge off, putting the output
+ * into high impedance mode. */
+static void bridge_off(void)
+{
+	PORTD |= D_1_MINUS | D_2_MINUS;
+	PORTD &= ~(D_1_PLUS | D_2_PLUS);
+}
+
+/* Turns the H-bridge on, setting 1+ 2- */
+static void bridge_on_a(void)
+{
+	bridge_off();
+	_delay_ms(100);
+	PORTD |= D_1_PLUS;
+	PORTD &= ~D_2_MINUS;
+}
+
+/* Turns the H-bridge on, setting 1- 2+ */
+static void bridge_on_b(void)
+{
+	bridge_off();
+	_delay_ms(100);
+	PORTD |= D_2_PLUS;
+	PORTD &= ~D_1_MINUS;
+}
+
+/* Initializes the output port needed for the H-bridge */
+static void bridge_init(void)
+{
+	bridge_off();
+	DDRD |= D_1_PLUS | D_1_MINUS | D_2_PLUS | D_2_MINUS;
+}
+
+int main()
+{
+	bridge_init();
+	/* simple demo, just flips polarity every now and then */
+	while (1) {
+		bridge_on_a();
+		_delay_ms(200);
+		bridge_on_b();
+		_delay_ms(200);
+	}
+}
+