Oh, duh!  I'm sure that's it.  Thanks!

-----Original Message-----
From: pic microcontroller discussion list =
[mailto:PICLIST@MITVMA.MIT.EDU] On Behalf Of Jan-Erik Soderholm
Sent: Saturday, June 05, 2004 19:58
To: PICLIST@MITVMA.MIT.EDU
Subject: Re: [PIC:] How to read more than one A/D pin?

Lindy Mayfield wrote :

> Here is one thing that I am trying, that isn't working:
>
> 1)  Set TRISA so that AD0 and AD1 are inputs
> 2)  Set ANSEL so that they are both analog

> 3)  Delay for acquisition time
> 4)  Set ADCON0 bits to select AD0 for AD

I think 3) and 4) are in the wrong order.

> 5)  Start AD conversion (ADCON0/GO_DONE) and loop until done
> 6)  Output 2 bytes to RS232 at 9600 baud
> 7)  Set ADCON0 bits to select AD1 for AD

Acquisition is missing here.

> 8)  Start AD conversion (ADCON0/GO_DONE) and loop until done
> 9)  Output 2 bytes to RS232 at 9600 baud
> 10) Goto 3
>
> Is this correct what I am doing here?

No, acquisition should be done *after* the channel
is selected (or changed). That is the time when the external
voltage is "acquisitioned" (read into the internal capacitor
in the AD converter).

Jan-Erik.

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