8x8 Scrolling LED display (Simple example)

[gabi68]

Hi Ioannis,

No, I do not have all the parts to try it. That was the reason for using Proteus. I saw a post from you regarding ULN 2083. If I decided to use that instead ULN 2004 what else should I need to modify (software and hardware)?

Regards
Gabi

[wellyboot]

regarding ULN 2083. If I decided to use that instead ULN 2004 what else should I need to modify (software and hardware)?

Regards
Gabi

ULN2803 is an 8 channel transistor array (18pin package), and the ULN2004 is a 7 channel transistor array (16pin package)

The software remains the same, with the hardware you can lower the component count, by replacing 2 ULN2004 with 1 ULN2803

[gabi68]

Hi,

After 1 month I finally make that running - simulating properly in Proteus. My problem was that ULN2803. I didn't know that chip invert signal's. After I put some hex inverters 7404 everything running properly.
My question is:
in real life (I will build the real circuit) I need that inverters or everything will run normal without that?

Many thanks
Gabi

[Ioannis]

Instead of inverters, why don't you invert he data that you output from the PIC?

Ioannis

[Ioannis]

Instead of inverters, why don't you invert the data that you output from the PIC?

Ioannis

[gabi68]

Hi Ioannis,

I try to do that but, I failed. Can you show my how? On the other hand the question it is still: do I need that inverters in a real circuit?

Thank you for your time
Gabi

[Ioannis]

If your load needs an 1 and you send a 0 then it is obvious that you need an inverter.

But as I said, instead of 1, send 0 in software.

For example,

var_a=%10101010

var_1=var_a XOR %11111111

The result in var_a will be the complement of the initial value.

Ioannis

[wellyboot]

Hi all,
This update now scrolls temperature in degrees C & F,
with indication arrow to show increase or decrease in temperature
and scrolls 'wellyb00t' at every few minutes.
Works with PBP 2.60C & MPLABS v8.63