Maybe modify the if statements a little.

if(0x00<=adc_result<0x0F)
becomes
if((0x00<=adc_result) and (adc_result <0x0F) )

Also, are you using signed byte values?  Is 0xFF a negativre value?

The //else comment is a bit confusing.  You do not have a "if, else if " set 
of statement,  You have two independent if statements.

Bill

----- Original Message ----- 
From: "Paul Duffy" <paulduffy@comcast.net>
To: "pic microcontroller discussion list" <PICLIST@mitvma.mit.edu>
Sent: Monday, January 16, 2006 4:35 PM
Subject: newbie question - basic logic and a/d converter


>I am working with the 16F684, using the BoostC compiler and the MPLAB IDE. 
>I am learning how to use the A/D converter.  For now, I am reading in a 
>voltage and turning on one bank of LEDs if it is less than a target value, 
>and the other bank of LEDs if it is greater than the target value.  Pretty 
>simple stuff.
>
> The first part of the code seems to work and is
>  int adc_result;                   //integer for storing 8 bit a/d result
>  void main()
>  {
>   cmcon0 = 7;                    //turn off analog comparators
>   ansel = 0b00001;             //select AN0 (pin 13, RA0) as A/D input
>   adcon0 = 0b00000001;     //turn on A/D, select RA0/AN0 as input, don't 
> start conversion
>   adcon1 = 0b00110000;     //select internal RC clock
>   intcon = 0;                      //turn off interrupts
>   t1con = 0;                       //turn off timer 1
>   porta = 0b111111;
>   portc = 0b111111;
>   trisa = 0b000001;             //set port a as output, except RA0
>   trisc = 0b000000;             //set port c as output
>
>   while(1)
>   {
>   delay_ms(500);                //delay between loops
>   set_bit(adcon0,1);            //start a/d conversion
>   while (!test_bit(adcon0,1)); //wait for completion
>   adc_result = adresh;         //store a/d result
> The following code works
> .
> .
> .
>  if(adc_result<0x0F)  //if a/d count is below F then
>    {
>    porta = 0xFF;    //turn on port a
>    portc = 0x00;    //turn off port c
>    }
>
>   if(0x0F<=adc_result) //if a/d count is above or equal to F then
>    {
>    porta = 0x00;    //turn off port a
>    portc = 0xFF;    //turn on port c
>    }
>
> but this code does not
>
>  if(0x00<=adc_result<0x0F)  //if a/d is below F then
>    {
>    porta = 0xFF;    //turn on port a
>    portc = 0x00;    //turn off port c
>    }
>   //else
>
>   if(0x0F<=adc_result<=0xFF) //if a/d is below F then
>    {
>    porta = 0x00;    //turn off port a
>    portc = 0xFF;    //turn on port c
>    }
>
> I'm sure I am overlooking something simple, but after a few hours of 
> experimenting, I am stuck.  I'd appreciate any help.
> Thanks.
> -- 
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist 

-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist