Hi again

I was curious as to whether my choice of words might be understood

I also understand that it not actual programming that you need help on but the physical architecture of your proposed project for school, and that you may have run out of I/O pins. You could implement a port expander using a 74LS164 accessed serially that would give you 8 I/O's for every 2 used to control it.


You could consider making use of the hardware comms peripheral features that this chip has.

The difficulty is that your information is still far too vague, for me anyway. It would be useful to list which pins you have connected to what and how you are implementing your existing layout. And exactly what you want to add, ie I have three I/O pins left how can I add a 16 button keypad.

ie I have a printer connected to PORTA I have my LCD connected to PORTB I have my barcode reader connected to PORTC and my button connected to PORTD

Do you have a schematic you could post, or even a photo of your existing work in progress. Perhaps a photo of a quick pencil sketch, a picture speaks a thousand words in any language.


Duncan