LCD problem

[Dwayne]

You say backlight LCD....

Try checking your current drain... How much current are you pulling with everything?

Reason why? I purchased a LCD from electroncs place...connected it up, and almost promptly overloaded my 7805 (which didn't have a heat sink on it). The current drain was 300+ mills just for the LCD!.... Needless to say, I switched LCD's. and only destroyed 2 7805's before I found out what was happening.

Could you be overloading your supply, and the supply shutting down? Can you verify that your 74HCT373, 74HCT245 are working, eventhough the LCD is dead?

Dwayne

[NavMicroSystems]

Allow some time for leonel to come back with some more details.

Or do you want to continue providing solutions he has got to find a matching problem to?

[leonel]

I'm back
My problem it´s that:
In the beginning of my project i had a problem wiht backlight but now it works putting My Vcc at +5V.
My ideia of putting two diodos at the end of my regulator it´s having my PIC with one isullated suplly, and the rest of my circuit with one different suplly. I'll have one independent +5V to the PIC...
If i put PIC, LCD, 373 with the same suplly it works, but if i put PIC, LCD, 373 and 245, this is all circuit with my output regulator it doesn´t work.
This morning i'll try doing more tests then at the end of the day i'll tell you more thinks...

Note: sometimes i don´t say too much because i don´t write very well in english.

[Melanie]

I've either been up too long, or in desperate need of some more coffee... just misread "two diodos " as something completely different!

As long as you have a common 0v, it shouldn't matter how many different supplies you have. Are you overloading your Regulator? When everything is connected (and not working) what is the +V on each device?

[leonel]

This morning i put 2 regulators, but the problem still happens.
I thing that i´m not overloading my regulator. I'm using 7805 that supports 1A.
With this morning tests i think that my problem it´s with my 74HCT245. And why? When i put 4.3V on my 74HCT245 i don´t have problems in the display. I see the datasheet and there´s a diference between 74HCT245 and 74HC245. For HC the condition is VI = GND to VCC For HCT the condition is VI = GND to VCC - 1.5 V. What´s this meaning? That i cannot put Vcc to +5V or my inputs/outputs have to be 5-1.5=3.5V????

Melanie said:
When everything is connected (and not working) what is the +V on each device?

In each device i have +4.9V.

[leonel]

As i said i'm giving more news...
I changed my 74HCT245 to 74HC245 and i have no problems... I don´t understand very well but it works!
Now i only have one problem
My MCLR has the circuit attached, but when i close my circuit almost the time doens't do the reset. But if i put my multimeter between pins 1 (MCLR-Vpp) and ground, to measure my voltage it works fine...
What probably it's happening??
What can i do?

Sorry to have strange questions and strange problems, but i'm new in this matter and i like to understand the problems.

[Dave]

leonel, With the diode in the direction that it is the Processor will never reset with the pushbutton. What is the reason for the diodes direction?

Dave Purola
N8NTA