The MAX7219 tend to induce a lot of EMF interference, I used those in a project a couple of years ago and the multiplexing caused noise in the radios PLL/VCO system, despite a great deal of filtering being used, it was radiating from the led display cables !
The MAX7219 tend to induce a lot of EMF interference, I used those in a project a couple of years ago and the multiplexing caused noise in the radios PLL/VCO system, despite a great deal of filtering being used, it was radiating from the led display cables !
You can buy a 4-digit 14-segment LED with the 7219 built in... just sayin'.