Handle PWM on pin PD4, PD5 and PD7

src/common.h

@@ -3,11 +3,15 @@
 
 #include <stdarg.h>
 
-#define BIT(n)    (0x1U << (n))
-#define UNUSED(s) (void)(s)
+#define BIT(n)            (0x1U << (n))
+#define UNUSED(s)         (void)(s)
+#define MAX(a, b)         ((a) > (b) ? (a) : (b))
+#define MIN(a, b)         ((a) < (b) ? (a) : (b))
+#define CLAMP(n, hi, lo)  (MIN(hi, MAX(n, lo)))
 
 void Info(const char *fmt, ...);
 void Error(const char *fmt, ...);
+double Clamp(double n, double upper, double lower);
 
 #include <util/delay.h>
 #define Sleep(ms) _delay_ms(ms)