22.3.1 Initialization and Disabling

To initialize the TCD:
  1. Configure the static registers to the desired functionality.
  2. Write desired initial values to the double-buffered registers.
  3. Ensure that the Enable Ready bit (ENRDY) in the Status register (TCD.STATUS) is set to '1'.
  4. Enable the TCD by writing a '1' to the ENABLE bit in the Control A register (TCD.CTRLA).
It is possible to disable the TCD in two different ways:
  1. By writing a '0' to ENABLE in TCD.CTRLA. This disables the TCD instantly when synchronized to the TCD core domain.
  2. By writing a '1' to the Disable at End of Cycle Strobe bit (DISEOC) in the Control E register (TCD.CTRLE). This disables the TCD at the end of the TCD cycle.

The bit fields in the TCD.CTRLA register are enable-protected, with exception of the ENABLE bit. They can only be written when ENABLE is written to '0' first.