Pushbutton problems

[apl01]

Hi there,

i am wanting to perfrom rs232 comms with quite a few PICs. First of all since i am new to CCS i am constructing basic programs to help me get familiar with the syntax etc. My first program to blink an LED was no problem but now i want to use a pushbutton to turn on (when held) an LED on a 12F675. I have tried almost everything but still no luck the code i am using is:

#include <12F675.h>
#device ADC=10
#fuses INTRC_IO,NOWDT,NOPUT,NOPROTECT,NOCPD,NOMCLR
#use delay(clock=4000000)
#define GP0 PIN_A0
#define GP1 PIN_A1
#define GP2 PIN_A2
#define GP3 PIN_A3
#define GP4 PIN_A4
#define GP5 PIN_A5

void main()
{
while(1)
{
if ( input(GP1) )
output_high(GP2);

else
output_low(GP2);
}
}

i have tried variations to include if ( (input(PIN_A1) )==1) ans so on but all that happens is the LED remains on regardless of the state of the pushbutton.

Have i missed something?

[Ttelmah]

How is the 'pushbutton' connected?. To detect a switch, you normally need it to connect the button to 0v (say), and have a _pull up resistor_, so that the pin goes high when it is not pressed, and low when it is pressed. A button on it's own (without a resistor), can't (easily...) be detected. The PIC itself, has the ability to turn on internal 'resistors' for this type of operation. Unless there is something like this, to change the state of the pin, when the button is not pressed, the input, will pretty much stay at the state it was, when the button was pressed, and nothing will happen...
Look at the 'port_a_pullups' command, and wire your switch to 0v, then see what happens.

Best Wishes

[apl01]

Yes you are right, silly me. Thanks for your help.