Comparing port bit

mtheriault2000 · Joined: 12 Oct 2005 Posts: 9

Hi

I'm trying to compare the polarity of a port pin and the bascic does'nt allow me to do it. I want th check if the port pin status as change

Dim Gear_previous As Bit
Gear_in Alias P0.4

gear_previous = gear_in
set gear_in

do
...
call gear_check()
loop

Sub Gear_check
If Gear_in <> Gear_previous
Then
Waitms 25
If Gear_in <> Gear_previous Then
Gear_previous = Gear_in
Call Position_
End If
End If
End Sub

Bascom give me an error on this line : If Gear_in <> Gear_previous

Whats wrong?

Martin

Vilko

My answer might be not correct, but

When compare is made and one of arguments in portpin you need to take in consideration this:

I think, that bascom does not read port in if statement. I think, that bascom supposes that the value of Px.y is that, last used when portpin was writen.

The best way to verify my opinion is to try. I am not able to do this now, because of my hardware is down.

Try this way:

Write to port:
P1 = 255
then push some bit of port1 down with a switch connected between pin and ground then

if P1 = 255 then
print "Vilko is right "
else
print "Vilko is wrong"
endif