I can't really say for sure what is going on without seeing more info,
but from my understanding of the code, it seems that you're calling
checkFinger() in a pretty quick loop, and that if it gets what it
thinks to be a positive reading it toggles the LED.  So if your sensor
was working, when you touched the lamp, the LED would flicker quickly.

So I think if your sensing isn't working right and thinks you're
touching the lamp, a quickly flickering LED is just what I'd expect.
I think what you need is something like:

int last_switch = 0; // global

// then in your check finger loop
if(GPIO3) {
  if(!last_switch) {
    toggleLed();
    last_switch = 1;
  }
} else {
  last_switch = 0;
}

I also wouldn't be surprised if there are hardware or firmware issues
with the sensing technique.  Have you seen
http://www.qprox.com/products/product_summary.html ?

-n.




On Wed, Jun 18, 2008 at 9:03 PM, mossy173 <mossy173@gmail.com> wrote:
>
> Enormous thanks to everyone for the help on the last project.  That's now
> done and working well, and I'm on to something bigger and just as
> inexplicably nonfunctional.  I have the PIC wired with a metal lamp between
> pins 3 and 4, and an LED between pin 0 and ground.  The idea here is to
> charge and discharge the body of the lamp very quickly, and if at any point
> discharging takes too long, that indicates human contact and accompanying
> increase in capacitance.  Instead, the LED just flickers very quickly and
> dimly regardless of input.  The wait time here is very high just to make
> sure that the lamp lights, which it fails to.  Any ideas??
>
> -Eli
>
>
> #include <htc.h>
> #define LED GPIO0
> #define OFF 0
> #define ON 1
> #define EMITTOR GPIO2
>
> void checkFinger(void);
> void init(void);
> void delay(int delay);
> void toggleLED(void);
>
> void main(void){
>        init();
>        LED = ON;
>        while(1){
>
>                checkFinger();
>
>
>        }
> }
> int z;
> void checkFinger(void){
>
>        EMITTOR = 1;
>
>        for (z = 0; z < 300; z++)
>                NOP();
>
>        if (GPIO3 == 1)
>                toggleLED();
>
>        EMITTOR = 0;
>        delay(200);
> }
>
> void toggleLED(void){
>        if (LED == ON)
>                LED = OFF;
>        else
>                LED = ON;
> }
>
> void init(void){
>     ANS3 = 0;
>     VRCON = 0;             //Turn Off Voltage Reference Peripheral
>     CMCON = 0x07;          //Turn Off Comparator Peripheral
>     TMR0 = 0;              //Clear Timer0
>
>     OPTION = 0x80;
>
>
>        TRIS3 = 1;
>        TRIS2 = 0;
>        TRIS0 = 0;
>
> //    INTCON = 0;
> /*      IOCB4 = 1;  //interrupt on change for pin 4 is on
>        IOCB = 0x00010000;
>        GPIE = 1;
>        T0IF = 0;
>        T0IE = 1; */
>
> }
>
> void delay(int delay){
>        int x, y;
>        for (x = 0; x< delay; x++){
>                for (y = 0; y<100; y++){
>                        NOP();
>                }
>        }
> }
> --
> View this message in context: http://www.nabble.com/newb%27s-capacitance-switch-implementation-tp17995271p17995271.html
> Sent from the PIC - [PIC] mailing list archive at Nabble.com.
>
> --
> http://www.piclist.com PIC/SX FAQ & list archive
> View/change your membership options at
> http://mailman.mit.edu/mailman/listinfo/piclist
>
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