[oopic] Re: A2D Troubles

--- In oopic@yahoogroups.com, "Fiebigc" <fiebigc@...> wrote:
>
> I'm relatively green with the OOPic and I'm trying my first A2D
> connection. I have the OOPic connected to an LCD that I've tested
> throughly that displays the values of the A2D. My problem is that it
> gives a nominal value for the voltage that fluctuates around 512. It
> does give meaningful values from 2.5v to 5v but nothing below that.
> Does anyone know what I'm doing wrong? Thanks.
>
> Here is my code snippet. I've left out the LCD stuff for brevity.
>
> Dim volt As New oA2D10
>
> Sub main()
>
> volt.IOLine = 1
> volt.Operate = 1
>
> do
> LCD.String = STR$(volt.Value) 'Outputs data to display on LCD
> OOPic.delay = 10
> Loop
>
> End Sub
>

What is driving the A2D input? There is a maximum driving impedance
of 2.5k ohms.

Is the signal ground from the input device tied to ground for the OOPic?

Try using a 10k pot with the ends tied to Vcc and Gnd through 220 ohm
resistors. Connect the wiper to the A/D input. The 220 ohm resistors
protect the OOPic in case the pin is accidentally configured as a
digital output and the pot is at an end position.

Richard

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