Part Project LM35 & 16F676

[pickit2]

As you may know the 16F676 is a pain to setup, so I will share the start of a project.
The rar file has Proton Basic files & Proteus DNS, so you can test setup before the build.
This is to monitor the output of a LM35 and Display the Temerature readings on a Lcd.

[frasenci]

Looks ok to me , and I would suggest you use another Voltage reference for using LM35

1.- LM35 out signal is only milivolts , for example 1000 mv or 1 v for 0-100 Degree Celsius diference.

2.- Connect Vref in PIC to an lower voltage so you can expand the scale

3.- This is easy to do with a voltage ladder of , let say 2 x 10 kohm resistors from 5V to ground and connecting Vref of Pic in the middle so Vref is 2.5V.  You must adjust your " PAYBACK " variable accordingly. And also configure ADCON0 register accordingly.

This will give you much more precisión in reading the temperature.

Greetings
Francisco

[jeanninemtv]

so you need a stable Vref...  better with a buffer opamp

[oldvan]

Older topic, but seemed incomplete so I'll add to it:

I'd suggest using a zener diode to create the reference voltage, so it will be stable even if power supply voltage isn't. 

Something like this:


Zener diodes are readily available at most 0.1V steps from 2 to 5.1 Volts.

[insane4evr]

Try an LM336x-2.5. It has tighter reference voltage tolerance and lower temperature drift. Just my 2 cents.

[bbarney]

Hey pickit, don't suppose you did a version of this with a 3 or 4 digit led display ?

[pickit2]

I did do, a (freq-counter or voltage) monitor for 6 digit 7seg display.
I will dig it out if you want.

[bbarney]

if you wouldn't mind,I had one made with a 16f690 but after getting bit by a bug I lost a lot of stuff and a bunch never worked after upgrading to the beta just 16f690 stuff and I did try the "Declare FLASH_CAPABLE = FALSE" trick that got the lcd to work but the code never ran right so I thought try leds again 

[babatundeawe]

try this from one of spency's tut
www.digital-diy.net