4.9.10.5 Limitations of debugWIRE

The debugWIRE communication pin PC0 is physically located on the same pin as external NRESET. An external reset source is therefore not supported when the debugWIRE is enabled. The debugWIRE system accurately emulates all I/O functions when running at full speed, i.e., when the program in the CPU is running. When the CPU is stopped, care must be taken while accessing some of the I/O registers via the debugger (AVR Studio). A programmed DWEN fuse enables some parts of the clock system to be running in all sleep modes. This increases the power consumption while in sleep. Thus, the DWEN fuse must be disabled when the debugWIRE is not used.

The debugWIRE supports only two breakpoints in the ROM program memory areas.