LCD problem

[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

[leonel]

In datasheet of 18F458 pag 23 section 3.0 (Reset) there´s a schematic. I did a little changes to use a switch and make a reset through a switch... It´s not the first time i'm using this circuit and in the others have been working!

[mister_e]

I still prefer the KISS engineering... but it's my own opinion.

how about something like that
<img src="http://www.picbasic.co.uk/forum/attachment.php?attachmentid=394&stc=1">
you can remove the toggle switch...

In fact to do ICSP i use the above in conjunction with a simple ICSP switcher like that
<img src=http://www.picbasic.co.uk/forum/attachment.php?attachmentid=163">
This allow me to do everything for developpement without install/remove the ICSP connector.

[Acetronics2]

Hi, leonel

Try a Schottky diode ( BAT 85 i.e. ) or Germanium diode ( OA ...) instead of the 1N4148 ... its leakage current will make your reset circuit work better !!!

that's not very elegant ...but will work !!!

Alain

[leonel]

What i did and it works was putting a R=100K between pin 1 and ground, in conjunction with my circuit.
What's the "KISS engineering"?

[mister_e]

Well a pull;-down should be bellow 10K and will affect your current design.

KISS engineering... not meant to be ofendant by any way...of course
Keep It Simply Stupid Engineering.

That's my favorite method.

[Acetronics2]

Everything that avoids a floating pin condition works ....

as Ralf wrote : RTFM !!! ( for humour here ... but found at page 9 or 10 !!! )

Alain