20.6.1 Entering External Programming Mode

The TPI must be enabled before external programming mode can be entered. The following procedure describes, how to enter the external programming mode after the TPI has been enabled:
  1. Make a request for enabling NVM programming by sending the NVM memory access key with the SKEY instruction.
  2. Poll the status of the NVMEN bit in TPISR until it has been set.

Refer to the Programming Interface description for more detailed information of enabling the TPI and programming the NVM.