Using PIC as a Low Voltage Meter, need help

Hello everybody, I have used pics before and I am still green, I managed to create inputs and outputs ok, used some time delays, but i now have a need to create a PIC managed voltage meter in the range of 0 to 2 volts., also must have four places. I have seen PIC controlled LCD and LED displays. Iam open on either. I do have the schematic for a PIC16F877A but no code! Can any body help with the code to get this project underway?

Thanks in advance, I have tryed other forums with little to no responce, I am starting to believe that its not a easy task.

Hi Doable

I'm not sure if anyone could help without knowing details of your board. Maybe you'd like to consider posting the schematic of your board to get ideas flowing.

Thanks Jerson,

Heres the schematic of a PIC 16F876A with a LCD display showing 2 lines, able to output 2 voltages as i need.

This looks like what i need, i cant get any responce form the site that has posted this schematic!

Its a pleasure to get a responce to the question, thanks again Jerson.

Hi, Doable

I think a look to the SAMPLES folder of your PbP CD will show you how to deal with the PIC A/D converter ... and display the result.

search for "ADCin xxxxx.bas"

The link you gave only allows ( with buying the '876 ) a 0 - 7v range ... by changing the input divider ratio.

These examples are for '877 and '876 ... surprise !

Alain

Hello Alian,

I am using Microchip PICkit-2 and MPLAB, are the SAMPLES folders you speak of on those disk? If not wher can i get the sample folders of PbP CD?

Alain gave you the direction, to your legal obtained CD. Are a legal owner?

Ioannis

Hi, Ioannis

As those files are free to download for every one ... and considering our friend's profile ...

let's give this link without any indiscreet further question ...

http://www.melabs.com/resources/samples.htm

Alain

Okie-dokie Alain...

Ioannis

Thanks Alian for the information,

I dont want to sound stupid but i have little experance in the PIC world, but have a great thurst to learn. Now with the system i am using are the code examples compatable. I have done enough to have learned that even between different PIC the basic code changes, I dont understand Microchip's reason for that.

I will attemp to write to a PIC16F877A the sample code for the voltage meter, I am sure that i have more questions later on. Thanks again for helping with this!

Quote:

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Originally Posted by Acetronics

let's give this link without any indiscreet further question ...

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Probably never seen the 'little green book' either...

Hi, Ski

As Mel said ... let's be helpful, ... !!!

Alain

One thing you can do is to take away the resistor network on your analog inputs and just put a 1k in place of the 100k(for isolation and input protection). That resistor network is scaling a 0-70v input to a 0-5v in to the PIC.

Then connect a 2 volt source to AN3 to serve as the high voltage ref. To do this you need to set register bits PCFG3-0 to '0001'. This changes the range of the ADC to 0-2V, instaed of 0-5v. You could use a simple resistor divider like 3k/2k or a precision voltage reference like a LMV431 or even a zener diode.

Thanks Tim for the info, i will try that and let you know how it worked.