atmega323l ATMEL Corporation, atmega323l Datasheet - Page 163

• Manufacturer Part Number: atmega323l
• Description: Atmega323 8-bit Avr Microcontroller With 32k Bytes Of In-system Programmable Flash
• Manufacturer: ATMEL Corporation

Using the JTAG
Programming
Capabilities
Bibliography
1457G–AVR–09/03
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 MCUSR Register must
be cleared to enable the JTAG Test Access Port.
The JTAG programming capability supports:
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•
•
•
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.
A description of the programming specific JTAG instructions is given in “Programming
specific JTAG instructions” on page 202. The details on programming through the JTAG
interface is given in the section “Programming via the JTAG Interface” on page 202
For more information about general Boundary-Scan, the following literature can be
consulted:
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Flash programming and verifying
EEPROM programming and verifying
Fuse programming and verifying
Lock bit programming and verifying
IEEE: IEEE Std 1149.1-1990. IEEE Standard Test Access Port and Boundary-Scan
Architecture, IEEE, 1993
Colin Maunder: The Board Designers Guide to Testable Logic Circuits, Addison-
Wesley, 1992
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