I have developed a custom ATMEL2560 PCB. I have D13 (pin 26 on uC) connected to a motorized door latch release. When I upload new code using the IDE or Visual Studio(with Visual Micro ext.), D13 goes active while upload occurs. Also pulses high 2 times when manually reset. I don't want the door latch to release when there is a power failure or reboot.
Could it be something to do with the ICSP? Not sure why as I'm not using D13 for ICSP - using D50-51 instead for ICSP. I'm flashed the Arduino bootstrap loaded by using a Genuine UNO as the programmer. I have no problems with uploading new code. My only problem is D13 becomes an active output - even when configured as an input.
Any suggestions on a root cause or clues toward finding a fix?