I'm going to build a LED-Wall which i will control via 4 teensy micro controllers. Everywere I read the vertical number of my LEDs has to be a multiple of 8? Does it really have to be so?
Thank you
No.
The number 8 is the factor of number of output pins in a port of most digital electronics component (shifters, drivers etc) which assumes a output word to be 8 bits.
A port in a general purpose MCU or MPU will have 8 pins.
Thus the whole available pins can be utilised without wastage.
ATmega168P/328P in arduino, has 3 ports. PORTB, PORTC, and PORTD.