Pic12f675 + Pcf8574 + Lcd

[Bostjan]

Hello !

This is my first post here. I'm asking if it is possible to drive a standard 16x2 lcd via PCF8574 I2C I/O expander with PBP code directly.
I've done V and A meter with 2 channel ADC in PIC12F675 (0-50V, 0-5A) and I was thinking to output measured data on the LCD. The problem is the small number of I/O pins on the PicMicro. My idea is to use the I2C port expander. This type of controlling the LCD I saw on the net but was implemented in C programming language.
Any help will be apriciated !

[J. Mark Wolf]

I have used the PCB8574 extensively and I see no reason why it won't work.

It's a little convoluted and will be a little slow because you'll have to send an entire message to the PCF8574 just to wiggle one of it's output pins, etc.

You may want to consider the EDE702 chip, can't remember the supplier, do Google search) it's basically a smart LCD serial interface chip for just a few bucks. I think they're also available at JDR and/or Jameco.

[Acetronics2]

Hi, Bostian

No problem to do it ... a french speaking electronics magazine ( Elektor or Electronique pratique ...i'll look for, if you want ) has already published that idea ...

Just a bit boring sending bytes to the LCD, a bit slow also, but works perfectly.

Alain

PS: Note I2C LCDs are sold ready to use on the market ...

[Bostjan]

Thanks for your answers. I wish to use PCF because I have some. Can you give me some further info because I'm just trying to get into PicMicro programming. In short I'm a real beginner. I dont won't the finished code but just explanation in a few step by steb guide how to deal with my problem. I understend the operation with clasic conection LCD to PIC but I dont understend what data I have to send to PCF for making work the LCD. Please remember that I'm a begginer (mechanical engeneer) who wants to learn!

Thanks again for your help

[Acetronics2]

Hi, Bostjan

I Finally got it ...

Elektor magazine project 030060 ... see their site in the netherlands for an English version.

Alain

[Bostjan]

Thanks! I will look to this project.