LCD Display not working - PIC heating...

[keithdoxey]

Still getting the same effect on my displays = first line, all pixels on; second line, all off - like picture in attachment in post #1.

Have you got a contrast pot connected and does the display change when you adjust it ?

[malc-c]

Also without a data sheet you're making life hard for yourself as you are assuming that they follow the Hitachi 44780 standard, and trust me there are some variations on that standard. I had some LCD's that required a dual rail supply for the contrast. I didn't get anything showing until I had -5v on the contrast pin !

The only way you are going to work out what is casuing the PIC to heat up is to pull everything off the breadboard and start again, and test at various stages, like connect up just the supply to the PIC and see if it heats up.. if it does then you need to check the supply to the PIC. I can't follow your threads above, but it seems like your using the PSU that powers the programmer - if so don't and try a seperate regulated 5v supply to the breadboard. The use of a 1amp 7805 regulator and a couple of 100uF capacitors will make a suitable supply for the test bed.

From experience I also find that strange things can happen if you use ICSP and leave it connected to the programmer after loading the HEX. You may even find that this is the cause, and would suggest you make up a simple header from 0.1" pitch header pins so that after programing the header can be removed. This way you can test the circuit correctly, and eliminate any possible causes.

[BobK]

Hi flotulopex,

Open the PBP manual to section 5.39 LCDOUT. One the third page of the LCDOUT explanation is a listing of the DEFINES for setting up a two line LCD display. On the following page is a sample of connecting a LCD to a 16F84A.

I think if you're getting "BLOCKS" to show on your display that the display is okay, it just needs a contrast adjustment. If your PIC is heating up, something has to be either inserted backwards in the breadboard or wired incorrectly. I've built the circuit in the manual and it worked!

It is very possible that your LCD may not be Hitachi 44780 compatible and it needs a different setup configuration.

We haven't heard anything on your level of experience with electronics. PICS do not have the power pins laid out like other ICs where their's are normally 14 or 16 for Vdd and 7 or 8 for Ground. Try sitting back and looking at everything you have hooked up and take your sketches or drawings and follow each and every little connection from point A to point B then check them all again. I can't believe you haven't gotten this problem resolved yet! It has to be something really simple!

We all gone thru this kind of stuff at one point or another so we understand what you might be experiencing. Be patient and you will find it.

BobK

[walphon1]

I had the exact same problem. I even went out and purchase a new LCD. PIC basic allows you define the pins in order to use the LCDout function. My mistake was that after checking the output in which I was using to communicate the LCD, I was getting nothing on porta.0 and porta.1. That is because this set up for analog input by default. I had to find out the hard way. I redefine my pin layout and I use other pins on the PIC and it works. I am 90% sure that is your problem. Hopes this is helpful.

[RUBiksCUbe]

I had almost the exact same problem but with an 18F252 and without the heating issue. It ended up being a bad LCD screen.

[flotulopex]

Helle Everyone,

Thank you for all your suggestions.

Let me give you these comments to your posts:

- Yes, the contrast works fine; but only on first line of the display - as long as I won't have find the specific data-sheet for this display, I'll have a doubt so I will buy a new one (already done yesterday - should arrive today);

- The first display I used must have had a problem - since I use my second one, the PIC is staying "cold";

- About the wiring which is very simple, I effectively started all over again with coloured wires to avoid any mistakes;

- I use ICSP and keep only the Vdd and GND pins connected after the programming operation - I have built the AN589 programmer and added a switch to connect/disconnet MCLR, DATA and CLOCK instead of removing wires each time (btw, how do you do this?);

- Yes, I used the example in the PBP manual and since it was not working, I found other examples such as Mikroelectronika and Chuck Hellebuyck's book;

- My knowledge in electronic is basic (I'm an electrician) and have been making lots of gadgets for years - I would not be able to develop a complicated circuit even if Ohm's law is not a problem to me - I mostly grab some peace of schematics from here and there and adapt them together.

I highly appreciate your help and I won't make you waste your time anymore until I am sure about the display I use. I cannot believe it still doesn't work after all your suggestions.