Can I multiplex the signals to keypad and LCD?

jake-XROV

HI, I'm trying to not buy a serial LCD as I've got a good Parallel one.
But I also needing to hook up a keypad and a temp sensor and relay
for a reflow oven I want to build. Any Ideas?
maybe a shift register? Thanks for any help.

Microcontrolled

If you want an easy but not as cheap fix you can try this:
www.sparkfun.com/commerce/product_info.php?products_id=258

I realize you are trying to cut down on I/O Pins?
If you are, you can try this:

www.parallax.com/Portals/0/Downloads/docs/cols/nv/vol1/col/nv43.pdf

If you don't already have something for the keypad, this will help out as well.

www.parallax.com/Portals/0/Downloads/docs/cols/nv/vol1/col/nv22.pdf

The complimetary I/O pins article was written in 1998 so that IC might not be availible anymore.
If you know how you could program an SX to convert parallel to serial for the keypad and for the LCD.

When you get your reflow oven done, post it on the Compleated Projects page. I would love to see it.

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Toys are microcontroled.
Robots are microcontroled.
I am microcontrolled.

vaclav_sal

You may have already tryed this - but most parallel LCD's will operate in "4 bit" mode thus "saving" 4 I/O pins.
·

Chris Savage

The following BS1 Applications Notes shows how to connect 4 push-button switches in parallel with the LCD data lines. The second link is to a Nuts & Volts article that shows how to connect a 4x4 keypad. I hope these help.

http://www.parallax.com/dl/appnt/stamps/bs1Appnotes.pdf

http://www.parallax.com/Portals/0/Downloads/docs/cols/nv/vol4/col/nv97.pdf

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
Chris Savage
Parallax Engineering