Generate a PWM signal for the display

Generate a variable duty cycle PWM signal for the dimmable display
backlight at a frequency of 1.25kHz.

For demo und testing purposes PD5 is currently fading between 0 and
100%.

firmware/src/main.c

@@ -0,0 +1,31 @@
+#define	F_CPU   8000000UL
+
+#include <avr/io.h>
+#include <util/delay.h>
+#include <stdbool.h>
+
+int main(void) {
+    // FastPWM: 1.25kHz
+    TCCR0A = (1 << WGM01) | (1 << WGM00) | (1 << COM0B1);
+    TCCR0B = (1 << CS01) | (1 << WGM02); // prescaler = 8;
+    OCR0A = 100;
+    OCR0B = 10;
+    DDRD |= (1 << PD5);
+
+    bool reverse = 0;
+
+    while (1) {
+        _delay_ms(1);
+
+        if (OCR0B > 100)
+            reverse = !reverse;
+
+        if (reverse)
+            OCR0B++;
+        else
+            if (OCR0B > 0)
+                OCR0B--;
+            else
+                reverse = !reverse;
+    }
+}