Doing SPI.Write from class constructor will brick Arduino Pro Micro
I had a small class to manage digpots (MPC410-10), and it all worked well. Until I’ve introduced write call in class constructor (now commented out). void DigPotUnitClass::Write(byte value) { digitalWrite(ChipSelectPin, LOW); SPI.transfer(B00010001); // This tells the chip to set the pot SPI.transfer(value); // This tells it the pot position digitalWrite(ChipSelectPin, HIGH); } DigPotUnitClass::DigPotUnitClass(byte chipSelectPin) { ChipSelectPin…