Atmel ATmega164P/V Manual De Usuario página 215

tracing into or stepping over functions, step out of functions, place the cursor
on a statement and
execute until the statement is reached, stop the execution, and reset the
execution target. In
addition, the user can have an unlimited number of code Break Points (using
the BREAK
instruction) and up to two data memory Break Points, alternatively combined
as a mask (range)
Break Point.
23.7 On-chip Debug Specific JTAG Instructions
The On-chip debug support is considered being private JTAG instructions, and
distributed within
ATMEL and to selected third party vendors only. Instruction opcodes are listed
for reference.
23.7.1 PRIVATE0; 0x8
Private JTAG instruction for accessing On-chip debug system.
23.7.2 PRIVATE1; 0x9
Private JTAG instruction for accessing On-chip debug system.
23.7.3 PRIVATE2; 0xA
Private JTAG instruction for accessing On-chip debug system.
23.7.4 PRIVATE3; 0xB
Private JTAG instruction for accessing On-chip debug system.
23.8 Using the JTAG Programming Capabilities
Programming of AVR parts via JTAG is performed via the 4-pin JTAG port,
TCK, TMS, TDI, and
TDO. These are the only pins that need to be controlled/observed to perform
JTAG programming
(in addition to power pins). It is not required to apply 12V externally. The
JTAGEN Fuse
must be programmed and the JTD bit in the MCUCR Register must be cleared
to enable the
JTAG Test Access Port.
The JTAG programming capability supports:
• Flash programming and verifying.
• EEPROM programming and verifying.
• Fuse programming and verifying.
• Lock bit programming and verifying.
The Lock bit security is exactly as in parallel programming mode. If the Lock
bits LB1 or LB2 are
programmed, the OCDEN Fuse cannot be programmed unless first doing a
chip erase. This is a
security feature that ensures no back-door exists for reading out the content of a
secured
device.
The details on programming through the JTAG interface and programming
specific JTAG