+ TCCR3A = ((0 << WGM31) | /* normal mode, OCR3A */
+ (0 << WGM30)); /* normal mode, OCR3A */
+ TCCR3B = ((0 << ICNC3) | /* no input capture noise canceler */
+ (0 << ICES3) | /* input capture on falling edge (don't care) */
+ (0 << WGM33) | /* normal mode, OCR3A */
+ (0 << WGM32) | /* normal mode, OCR3A */
+ (4 << CS30)); /* clk/256 from prescaler */
+
+ OCR3A = 1250; /* 8MHz clock */
+
+ TIMSK3 = (1 << OCIE3A); /* Interrupt on compare match */
+