The 16-bit Timer/Counter has been updated and improved from previous versions of the 16-bit AVR Timer/Counter. This 16-bit Timer/Counter is fully compatible with the earlier version regarding:

The following control bits have changed name, but have same functionality and register location:

The following bits are added to the 16-bit Timer/Counter Control registers:

The 16-bit Timer/Counter has improvements that will affect the compatibility in some special cases.