The AVR specific public JTAG instruction for entering programming commands via the JTAG port. The 15-bit Programming Command Register is selected as data register. The active states are the following:
- Capture-DR: the result of the previous command is loaded into the data register.
- Shift-DR: the data register is shifted by the TCK input, shifting out the result of the previous command and shifting in the new command.
- Update-DR: the programming command is applied to the Flash inputs.
- Run-Test/Idle: one clock cycle is generated, executing the applied command.