Add german documentation and matrix code

firmware/include/pentabug/matrix.h

@@ -0,0 +1,14 @@
+#ifndef MATRIX_H
+#define MATRIX_H 
+
+#include <stdint.h>
+
+void matrix_start(void);
+void matrix_stop(void);
+
+void matrix_show(void);
+void matrix_init(void);
+
+void matrix_set(uint8_t x, uint8_t y, uint8_t active);
+
+#endif /* MATRIX_H */

firmware/lib/matrix.c

@@ -0,0 +1,70 @@
+#include <pentabug/matrix.h>
+
+#include <pentabug/timer.h>
+#include <pentabug/hal.h>
+
+static uint8_t pixels[9];
+static uint8_t index;
+
+void matrix_init(void) {
+	DDRD |= (1 << 5) | (1 << 6) | (1 << 7);
+	DDRC |= (1 << 4) | (1 << 5);
+	DDRB |= 1 << 2;
+}
+
+static void move_line(uint8_t line) {
+	PORTD &= ~0xe0;
+	PORTD |= 1 << (line + 5);
+}
+
+static void write_line(uint8_t data[]) {
+	PORTC |= (1 << 5) | (1 << 4);
+	PORTB |= 1 << 2;
+
+	if(data[0]) {
+		PORTC &= ~(1 << 5);
+	}
+
+	if(data[1]) {
+		PORTC &= ~(1 << 4);
+	}
+
+	if(data[2]) {
+		PORTB &= ~(1 << 2);
+	}
+}
+
+static void matrix_int(void) {
+	++index;
+
+	if(index >= 3) {
+		index = 0;
+	}
+
+	move_line(index);
+	write_line(pixels + (index * 3));
+}
+
+void matrix_start(void) {
+	matrix_init();
+	start_timer(PRESCALE_64, 125, matrix_int);
+}
+
+void matrix_stop(void) {
+	stop_timer();
+}
+
+void matrix_show(void) {
+	uint8_t i;
+
+	for(i = 0; i < 3; ++i) {
+		move_line(i);
+		write_line(pixels + (i * 3));
+		wait_ms(3);
+	}
+}
+
+void matrix_set(uint8_t x, uint8_t y, uint8_t active) {
+	pixels[x*3+y] = active;
+}
+