PIC 16F627A Programming problem

[mas]

I am using the chip pic 16f627a

setting PORTA to inputs & PORTB to outputs >>

bsf STATUS,PR0
movlw 0xFF
movwf TRISA
movlw 0x00
movwf TRISB
bcf STATUS,RP0

giving a high input to PORTA,0 >>

bsf PORTA,0
btfsc PORTA,0
******
$$$$$$

I used the btfsc(bit test skip if zero instruction) .. and the tested pin is set to '1' .. so the program shoudn't skip the ****** line


My problem is that the program skips the ****** instruction ,, and goes to the $$$$$$ instruction .. although the tested pin is set to high '1'

If any one knows where is the fault .. I am so gratefull

 

[eng1]

The pins of PORTA are configured as inputs.
Try this:

movlw 0x00
movwf TRISA

and see what happens.

 

[mas]

The pins of PORTA are configured as inputs.
Try this:

movlw 0x00
movwf TRISA

and see what happens.

Do you mean that if the pin is set to input .. Then I can't assign it to high or low ??

 

[TekNoir]

If I'm not mistaken, pins set as inputs have their bits set according to the incoming voltage level with VDD=Set and VSS=Unset. Don't forget to turn off the comparators to enable digital input.

 

[eng1]

Do you mean that if the pin is set to input .. Then I can't assign it to high or low ??

If you want to set or clear a bit of PORTA in software, that pin is an output by definition.

When a pin is configured as an input you can read its value, which depends on the applied voltage, as TekNoir said.

I guess you're trying to emulate a switch. If so, you configured PORTA correctly, but the last bsf instruction makes no sense.

 

[mas]

yes, I was trying to simulate

I will use a hardware circuit to test the program instead of the simulator

Thanks a lot guys

 

[eng1]

It is possible to apply a 'stimulus' with the simulator, but it's simple to add a switch with a pull-up resistor (external or internal) to your circuit.

Have fun