Simulator stimuli is a way to write simple script files that can read or write any register or memory location at a given time during simulation. The stimuli file can be started any time during simulation, and will continue until the end of the file or when the simulator session ends.
Starting with Atmel Studio 6.1, the File Stimulator found in AVR Studio® 4 has been reintroduced. There were two stimuli variants in AVR Studio 4. This is the most recent one used in Simulator 2. The older one is not supported.
Features of the stimulator:
Timing is expressed in terms of delay instead of absolute cycle counter values
Any I/O register can be assigned to (stimulated), not only port registers
Individual bits in I/O registers can be stimulated using bitwise assignments
Directives increase flexibility
One stimuli file can open and execute another stimuli file