31.10.6 PROG_PAGEREAD (0x7)
The AVR specific public JTAG instruction to read one full Flash data page via the JTAG port. The 2056-bit Virtual Flash Page Read Register is selected as data register. This is a virtual scan chain with length equal to the number of bits in one Flash page plus 8. Internally the Shift Register is 8-bit. Unlike most JTAG instructions, the Capture-DR state is not used to transfer data to the Shift Register. The data are automatically transferred from the Flash page buffer byte by byte in the Shift-DR state by an internal state machine. This is the only active state:
- Shift-DR: Flash data are automatically read one byte at a time and shifted out on TDO by the TCK input. The TDI input is ignored.
Note: 1. The JTAG instruction PROG_PAGEREAD can only be used if the AVR device is the first
device in JTAG scan chain. If the AVR cannot be the first device in the scan chain, the
byte-wise programming algorithm must be used.