ATmega325PA Atmel Corporation, ATmega325PA Datasheet - Page 43

• Manufacturer Part Number: ATmega325PA
• Manufacturer: Atmel Corporation

10.10.7
8285D–AVR–06/11
JTAG Interface and On-chip Debug System
ATmega165A/PA/325A/PA/3250A/PA/645A/P/6450A/P
If the On-chip debug system is enabled by the OCDEN Fuse and the chip enter Power down or
Power save sleep mode, the main clock source remains enabled. In these sleep modes, this will
contribute significantly to the total current consumption. There are three alternative ways to
avoid this:
• Disable OCDEN Fuse.
• Disable JTAGEN Fuse.
• Write one to the JTD bit in MCUCR.
The TDO pin is left floating when the JTAG interface is enabled while the JTAG TAP controller is
not shifting data. If the hardware connected to the TDO pin does not pull up the logic level,
power consumption will increase. Note that the TDI pin for the next device in the scan chain con-
tains a pull-up that avoids this problem. Writing the JTD bit in the MCUCR register to one or
leaving the JTAG fuse unprogrammed disables the JTAG interface.
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