ATmega16 datasheet(273/315 Pages) ATMEL

273 / 315 page

273

ATmega16(L)

2466E–AVR–10/02

Figure 138. State Machine Sequence for Changing the Instruction Word

AVR_RESET ($C)

The AVR specific public JTAG instruction for setting the AVR device in the Reset mode

or taking the device out from the Reset Mode. The TAP controller is not reset by this

instruction. The one bit Reset Register is selected as Data Register. Note that the Reset

will be active as long as there is a logic “one” in the Reset Chain. The output from this

chain is not latched.

The active states are:

•

Shift-DR: The Reset Register is shifted by the TCK input.

PROG_ENABLE ($4)

The AVR specific public JTAG instruction for enabling programming via the JTAG port.

The 16-bit Programming Enable register is selected as Data Register. The active states

are the following:

•

Shift-DR: The programming enable signature is shifted into the Data Register.

•

Update-DR: The programming enable signature is compared to the correct value,

and Programming mode is entered if the signature is valid.

Test-Logic-Reset

Run-Test/Idle

Shift-DR

Exit1-DR

Pause-DR

Exit2-DR

Update-DR

Select-IR Scan

Capture-IR

Shift-IR

Exit1-IR

Pause-IR

Exit2-IR

Update-IR

Select-DR Scan

Capture-DR

ATMEGA16 Datasheet(PDF) 273 Page - ATMEL Corporation