The OCR0x Registers are double buffered when using any of the Pulse Width Modulation (PWM) modes. For
the normal and Clear Timer on Compare (CTC) modes of operation, the double buffering is disabled. The
double buffering synchronizes the update of the OCR0x Compare Registers to either top or bottom of the
counting sequence. The synchronization prevents the occurrence of odd-length, non-symmetrical PWM pulses,
thereby making the output glitch-free.
The OCR0x Register access may seem complex, but this is not case. When the double buffering is enabled, the
CPU has access to the OCR0x Buffer Register, and if double buffering is disabled the CPU will access the
OCR0x directly.