I recently completed my serial LCD project. It is based on 74HC595 shift register, and it requires 3 pins of microcontrollers to drive a HD44780 character LCD.

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Details are found here.
http://picboard.blogspot.com/2010/09/serial-lcd-for-low-pin-count-pic.html

 

Thats helpful.

 

Very nice writeup Raj.

Actually you can use your same code with a 74HC164 IC too.

Challenge question: How can you drive a switch matrix with your circuit?

Cheerful regards, Mike

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Both the Predko 2-pin interface and the K8LH novelty 1-pin serial interface can be used to drive a switch matrix (below).