ATmega325P datasheet(293/364 Pages) ATMEL

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293

8023F–AVR–07/09

ATmega325P/3250P

25.8.4

PROG_COMMANDS (0x5)

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 (not always

required, see Table 25-17 below).

25.8.5

PROG_PAGELOAD (0x6)

The AVR specific public JTAG instruction to directly load the Flash data page via the JTAG port.

An 8-bit Flash Data Byte Register is selected as the Data Register. This is physically the 8 LSBs

of the Programming Command Register. The active states are the following:

• Shift-DR: The Flash Data Byte Register is shifted by the TCK input.

• Update-DR: The content of the Flash Data Byte Register is copied into a temporary register. A

write sequence is initiated that within 11 TCK cycles loads the content of the temporary

and the high byte for each new Update-DR state, starting with the low byte for the first Update-

DR encountered after entering the PROG_PAGELOAD command. The Program Counter is

pre-incremented before writing the low byte, except for the first written byte. This ensures that

the first data is written to the address set up by PROG_COMMANDS, and loading the last

location in the page buffer does not make the program counter increment into the next page.

25.8.6

PROG_PAGEREAD (0x7)

The AVR specific public JTAG instruction to directly capture the Flash content via the JTAG port.

An 8-bit Flash Data Byte Register is selected as the Data Register. This is physically the 8 LSBs

of the Programming Command Register. The active states are the following:

• Capture-DR: The content of the selected Flash byte is captured into the Flash Data Byte

new Capture-DR state, starting with the low byte for the first Capture-DR encountered after

entering the PROG_PAGEREAD command. The Program Counter is post-incremented after

reading each high byte, including the first read byte. This ensures that the first data is captured

from the first address set up by PROG_COMMANDS, and reading the last location in the page

makes the program counter increment into the next page.

• Shift-DR: The Flash Data Byte Register is shifted by the TCK input.

ATmega325P 데이터시트(PDF) 293 Page - ATMEL Corporation