Hi all, how are you?

R37 does nothing - it should be removed.

Why? if this is the "bridge" to carrier the 12V to the segment of the display in order to turn off this completly, from the Port C.

I have a question: In the circuit provided by AK, the direction of the current goes into the pin of the micro? can this damage the micro? I say this, because the pin is a output.

Captura de pantalla 2016-02-21 22.02.48.png... this circuit doesnt works. I dont have idea whats happen. Just seems like if the display segments turn on almost all time and turn off when they want.

 

Hi all, how are you?



Why? if this is the "bridge" to carrier the 12V to the segment of the display in order to turn off this completly, from the Port C.

I have a question: In the circuit provided by AK, the direction of the current goes into the pin of the micro? can this damage the micro? I say this, because the pin is a output.

Captura de pantalla 2016-02-21 22.02.48.png... this circuit doesnt works. I dont have idea whats happen. Just seems like if the display segments turn on and off when they want.

R37 is not a bridge that carries 12 v to the segment.

Trace the path of current flow from the 12V rail, through the PNP (top to bottom), through the display, through the NPN (top to bottom) and down to ground.

The signal from PORT D and PORT C of the microcontroller to the transistors are mearly switching those transistors and add little to the current.


Read my earlier posts carefully. The problem is explained and solved in those posts. Essentially you are not understanding how a PNP transistor works and there is no way you can turn off a PNP connected to a 12V power with a 5v microncontroller. Therefore, the NPN is added to the BASE of THE PNP.

The second NPN is fine and can be switched perfectly fine by the microcontroller with no need for R37.

 

Ok, thanks

Essentially you are not understanding how a PNP transistor works and there is no way you can turn off a PNP connected to a 12V power with a 5v microncontroller

Yes, I undestand what are you saying in previous post... thats the reason why I'm putting one level shifter by each output of the micro (in the port c and the port d ) but I made the circuit and doesnt works.