ISP Programming with External Crystal

Question: If the chip is clocked by an external 32.768KHz crystal (on the same pins used for in-circuit programming), should it be disconnected during programming?

 

Answer:

Since the crystal is not used during programming, it does not need to be disconnected during the programming phase. Please refer to "using external crystal oscillator" section of AN2014 for more details on pin loading requirements during programming.