Good idea! I made something similar. I used a sound meter so all hardware could be fitted in a chest. I added this function to the doIndication ino file. Looking at it now together with Gra Afch’s solution, the bitshifts are very useless 😉
Not sure what the digitalWrite does though…
void allNixiesOff()
{
// This is quite simple - just put everything to NULL
digitalWrite(LEpin, LOW);
unsigned long Var32 = 0;
SPI.transfer(Var32>>24);
SPI.transfer(Var32>>16);
SPI.transfer(Var32>>8);
SPI.transfer(Var32);
SPI.transfer(Var32>>24);
SPI.transfer(Var32>>16);
SPI.transfer(Var32>>8);
SPI.transfer(Var32);
digitalWrite(LEpin, HIGH);
}