i have a very simple question actually. Of 53 digital I/O pins on the mega are there any restrictions of using them? For example i have pins 50-53 reserved for SPI, a SD card reader to be precise, pins (2,3,4,5,11,12) for a LCD screen and pin 9 for a speaker. I know that pins 0,1 are for communication aswell as 14-21. But could pins 14-21 be used as normal I/O pins, since i will not be having a I2C or UART communication when the final program code works? Or am i obligated to use pins 22 to 49 for 11 sensors and 10 mosfets?