Pot Commands

[ngeronikolos]

Hello boys&girls,

I was working using a potetiometer conecting to my PIC16F628 via a capasitor to the GND.I want to read the resistor of a potetiometer(700ohm) whick included in an pan&tilt mechanism.I want to translate that to degree and display that on the LCD.
I manage to do that but I have a problem translating the resistor-->degrees!!
Range: 0-360
Resistor : 0-700ohm


Any idea??

In adittion,if I use the internal oscillator of the 16f628 the pins15&16 goes to RA6&RA7 without any additional command?

Thanks
Nikos

[CocaColaKid]

The POT command works between 0-255 when properly scaled so :

x = POT Value * 141
degrees = (POT Value * 141 / 100) . (POT Value * 141 / 10)

This comes from 360º / 255 = 1.41...

In order for this to work properly you must make certain you scale the POT command so that it reaches 255 at the very end otherwise the numbers will be off.

[nomada]

Hi

In adition to what cocacolakid wrote and as in the PBP manual I think that using 700Ohm will be a pain in the ...

They suggest to use something between 5k to 50k, I've already tried it with 1k pot and the results were not good.

I think that one of the real experts ( Melanie, Darrel, Bruce ...) on this things had already wrote that the best results were achieved with pot greater than 5K. Run a search

regards

nomada

[mister_e]

i'm not an expert but it read the RC time so, it will be a perfect match of your resistor and your Capacitor.

The logic will say ===> lower resistor + Higer cap = Higher resistor + lower capacitor.

[ngeronikolos]

Thanks boys for your usefull information.

I will try to read the POT Value and as cocacolakid said the
degrees = (POT Value*141)/100
displaied on LCD.

Cocacolakid,A GUESTION?For POT Value max = 255 how I should find the scale?

Does anyone have an expirience using smaller R than the range of 5k-50k?
I am going to measure a POT = 700Ohm

Please any adittional information would be grate for me.

Regards
Nikos

[CocaColaKid]

Look up the POT command in the manual. It has a really good description for setting the scale.