Not as simple as having the pin A1 configured as output and set low? 
Always see 0V that way ;-)

Rolf

fred jones wrote:
> Thanks for the reply.  I understand this.  Sorry if I didn't make it clear.  
> In order for this to work, as I understand it, there should be a high on the 
> A1 PIC pin and when the button is pressed, the PIC should see it go low and 
> then take A0 low in code.  The problem is that I can't get 5V on the A1 
> line, it stays low no matter what I've tried as previously explained.  I 
> figured putting a 10K pullup resistor to 5V on the A1 pin would give me a 
> constant 5V on the A1 pin until the button is pressed but still it doesn't 
> give me 5V on the A1 pic pin.
> Thanks,
> FJ
>
>
> From: Kevin Timmerman <lists@pcmx.net>
> Reply-To: "Microcontroller discussion list - Public." <piclist@mit.edu>
> To: "Microcontroller discussion list - Public." <piclist@mit.edu>
> Subject: Re: [PIC] one button on/off circuit problem
> Date: Mon, 11 Jun 2007 22:30:57 -0400
>
> A.1 is an input to the PIC so it can read the switch state.
>
> To turn power off, set A.0 low.
>
>
> At 09:46 PM 6/11/2007, you wrote:
>  >Hi all,
>  >I need to ask for help on something cause I obviously don't know what I'm
>  >doing ;-)
>  >
>  >I took this circuit here:
>  >http://www.pic101.com/pushpush.gif
>  >And I replaced the pass transistor with a P channel FET.  I can get it to
>  >turn on and latch with taking the pic pin A0 high, However I can't turn it
>  >off by getting 5V on pin A1.  I put a 10K resistor on the A1 line to 5V 
> but
>  >don't get a high.  I tried it with the 4.7K from collector to Gate as 
> shown
>  >and without.  I tried a 1Mohm resistor from Gate to Source in place of the
>  >10K.  No difference in any case.  I can't see a 5V signal at A1.  Help 
> with
>  >what I'm doing wrong is greatly appreciated.
>  >Thanks,
>  >FJ
>  >
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