Hey guys; I know I should know this from working with AVRs for so long, but I have never known?! I guess I just never had a reason to investigate it before; but the datasheet does not explain why.
When you select a clock source you also must select the startup time and such; for example on those fuse calculators; you can select like:
High Freq - Startup-Time 6CK + 4ms
High Freq - Startup Time 256CK + 2ms
and so on...
I always assumed thats just for allowing the power to even out and/or giving yourself a bit of time to enable other peripherals before the MCU starts or whatever; but I don't know forsure...
What is the purpose of selecting start-up times? And what are some examples of when to select XCK & Xms over say XCK & Xms?