IF...THEN inside a Loop

[Bill Legge]

Sorry - I made a silly mistake in the code I posted. The case where X=1 shows my error.

However, the real code that was/is causing trouble was for a larger range of X and included '>=', '<='.

My poor attempt to simplify the real problem failed!

I'll tidy up the real code and post it soonest.

Thanks for your input.

Regards Bill legge

[Bill Legge]

Sorry for my earlier muddled post. I've done some more work on the problem and have pinned down my difficulty.

I am compiling using PBPL and using a graphic LCD with 4 driver chips.
The GLCD is 240 pixels wide and I need to activate the Chip Selects as the display sweeps along:

0 to 63 CS1
64 to 127 CS2
128 to 191 CS3
192 to 239 CS4

The chip selects are connected to PORTB and my code is:

clear
DEFINE OSC 40	' Run on PIC18F8722, HSPPL
ADCON1	= $0F	' Set PortA to digital

TRISB=0               ' Make Port B outputs
PORTB=0	             ' clear the port

X	var	byte

Loop:
PORTB=$0		
for X = 0 to 239
	if X<64 then PORTB=$01
	if X>63 and X<128 then PORTB=$02
	if X>127 and X<192 then PORTB=$04
	if X>191 then PORTB=$08		
	pause 5
next X
goto Loop

If I compile using PBP it works properly and the chip selects turn on/off as X goes from 0 to 239.

If I compile using PBPL it does not work.

I need to use the LONG compilation. Any idea what is going wrong?

Regards Bill Legge

[Darrel Taylor]

Hi Bill,

No idea what's wrong at this point.
But I did run your program as is, no changes, on an 18F252.

Works the same with either PBPW or PBPL.

You can also do the same thing like this ...

for X = 0 to 239
  PORTB = DCD (X >> 6)
  pause 5
next X

Added:
So that it only affects those 4 pins, you could do this ...

PORTB = (PORTB & $F0) | DCD (X >> 6)

[mackrackit]

Silly question.
PM or MPASM ?
Or does it matter?

[Bill Legge]

I'm using MPASM because the PBP does not support the PIC18F8722

Regards Bill Legge

[Bill Legge]

Darrel T

Thanks very much for the code using DCD. It works fine with both PBP and PBPL.

I'd still like to find out why the IF...THEN won't work with PBPL?

Regards Bill Legge
In Australia