Writing to the watchdog's registers requires extra care compared to writing other peripheral registers. For example, the TCNT and TCSR registers are both written using the Write Window A register. When writing this register the user should make sure to use a word transfer instead of a byte transfer even though the TCNT and TCSR registers are 8-bits each. The top 8-bits, bits 8 - 15, are what distinguish which register is written.