LED dot matrix screen cathode can not switch triode, okay? What effect will it have?
Dot matrix screen, how many LED ah, say 16X16, there are 256 LED, assuming it all lit up, each LED current 10mA, voltage 1.5V, then let this lamp are all normal work, power is 256X1.5X0.01= nearly 4W, your IO microcontroller cannot provide such power
The control chip will burn out and the chip doesn't have enough current. Or not light, depending on whether he is working at high or low level.
You do not use the triode expansion flow, then can not afford to supply, that is, may not light, or will burn
