PIC16F88 Interfacing with LED MATRIX

Thread Starter

Mohit Mayank

Joined Mar 3, 2015
Hi, I am trying to interface PIC16F88 with 8x8 LED MATRIX, using 4017 and ULN2803. My aim is to built a binary clock, and before directly jumping to hardware I thought of doing the simulation on Proteus 8.1 .
So I interfaced the components and wrote the Embedded C program for the binary clock and tried to run the simulation on my computer, which as you have already guessed, didn't worked.

The main problem is ULN2803, it is not sinking current(i.e. there is no current flow on the right side of ULN2803)

Can Anyone please look at my circuit and tell me whats the problem there.
Thank you.


Joined Jun 22, 2012
i dont use simulation software, i build circuits to work on PCBs, the ic doesn't have a power supply, so i cant see how it can work?


Joined Nov 30, 2010
The differences between simulating and real circuits seems so very strange!
A, "real" circuit does not need a, "respak-7" (because R1 to R8 take care of that) but the ULN package needs a ground.
In simulation, you have to add unnecessary resistors and the grounds are, "provided"?
I'm so old that this makes my head hurt.