Newbie question about switch + led

[mradde]

start:
input porta.3   
low portc.0      
If porta.3 = 1 then led   ' when switch is pressed it goes to label "led" right?
goto start

led:
high portc.0    'here should the led light up?
pause 100
goto start
end

It happens NOTHING with this code.
If i change the value to "If porta.3 = 0 then led" the led always lights up except when switch is pressed down.
Any suggestions?

[mackrackit]

start:
input porta.3   
low portc.0      
If porta.3 = 1 then led   ' when switch is pressed it goes to label "led" right?
goto start

led:
high portc.0    'here should the led light up?
pause 100
goto start
end

It happens NOTHING with this code.
If i change the value to "If porta.3 = 0 then led" the led always lights up except when switch is pressed down.
Any suggestions?

How is everything connected?

[mradde]

It is the Low Pin Count Demo Board from PICkit2.
You can see schematic diagram in attached file!

[mackrackit]

Do you have JP5 connected?
Without JP5 connected you will get strange results.
With JP5 connected A3 will always be high, then when the button is pressed A3 will go low.

[Bill Legge]

I don't know what MCU chip you are using but if it has and A/D capability PORT A starts up in Analog mode. If this is the case you can fix the problem by:

1. Avoiding PORTA or

2. Looking up the A/D info in the MCU spec. This is often in the ADCON1 register and PORTA made digital by putting something like

ADCON1 = %00001111

near the beginning of your code. Good luck

Regards Bill Legge

[mackrackit]

I don't know what MCU chip you are using but if it has and A/D capability PORT A starts up in Analog mode. If this is the case you can fix the problem by:

The MCU should be a 16F690 ans A3 doubles as MCLR.

BTW.
How are the configs set ?