TOGGLE will not go LOW

[SUNFLOWER]

I have been writing complicated code for years without any troubles. Now something simple will not compile correctly. TOGGLE will not toggle low but does toggle high. Everything else seems to work ok but I am worried about this instability -- Rebooting computer did not clear this issue. Ideas on what's going on here?

DEFINE LOADER_USED 1 ' Bootloader space
OSCCON = %01100000 ' Internal oscillator speed 4 MHz 18F4620

MAINLOOP:

' LOW PORTA.0
PAUSE 50
TOGGLE PORTA.0
PAUSE 50

GOTO MAINLOOP

[Normnet]

I have been writing complicated code for years without any troubles. Now something simple will not compile correctly. TOGGLE will not toggle low but does toggle high. Everything else seems to work ok but I am worried about this instability -- Rebooting computer did not clear this issue. Ideas on what's going on here?

DEFINE LOADER_USED 1 ' Bootloader space
OSCCON = %01100000 ' Internal oscillator speed 4 MHz 18F4620

MAINLOOP:

' LOW PORTA.0
PAUSE 50
TOGGLE PORTA.0
PAUSE 50

GOTO MAINLOOP

Does the alternate "Low PORTA.0" work?
Perhaps the pin cannot be driven low?

Norm

[mackrackit]

http://www.picbasic.co.uk/forum/showthread.php?t=561

[SUNFLOWER]

Thanks, I was not aware TOGGLE needs to read digital, so can not toggle while doing some ADC on higher ports of A.

ADCON1 = %00001111 ' Make AN0-AN12 digital

[AvionicsMaster1]

I'm betting if you had a resistor pulling the pin low, say a 10k, you'd see it going low. I'm not familiar with the 18f4620 but on a 12f683 it needs some kind of load to pull the pin low. Don't have to be alot but something.

[spcw1234]

Adding these 2 lines should allow you to drive the pin.

ADCON1=15 'Set all A/D pins digital
CMCON=7 'Turn off comparators

[richard]

before you go too far down the wrong road read this thread about pbp and latx

http://support.melabs.com/threads/99...using-lat-regs

[boroko]

Thanks. of course Darrel would be the one to find something that obscure. Bet there's a story and some lost hours on that one.
Mark

[Archangel]

I have experienced this probably 50% of the time I have attempted to use toggle, High & Low commands and as such do not even attempt to use them.
Is there a definite cause / effect or relationship to their failure to work and setting TRIS registers? Can anyone point to a paragraph in the manual?

[richard]

from the pbp3 manual for HIGH

HIGH Pin
Make the specified Pin high. Pin is automatically made an output. Pin may be a constant, 0-15, or a variable that contains a number 0-15 (e.g. B0) or a pin name (e.g. PORTA.0).
HIGH 0 ' Make Pin0 an output and set it high (~5 volts)
HIGH PORTA.0 ' Make PORTA, pin 0 an output and set it high (~5 volts)
led Var PORTB.0 ' Define LED pin
HIGH led ' Make LED pin an output and set it high (~5 volts)
Alternatively, if the pin is already an output, a much quicker and shorter way (from a generated code standpoint) to set it high would be:
PORTB.0 = 1 ' Set PORTB pin 0 high
Since this command automatically sets the data-direction of the pin it acts on, the Pin parameter should only be a PORT or GPIO register (or an alias to a PORT or GPIO register). If the command is directed to act upon a LAT output or a bit within a variable or SFR, it will attempt to set a data-direction register that doesn't exist. The result may be unexpected behavior since a bit is changed in a seemingly random memory location. This can be very difficult to debug.

its also mentioned for other commands

[Archangel]

Ok I did some testing and I found:
1. High & Low worked without Tris or Ports set or analog settings set to digital
2. Setting port to 1 and zero worked with Tris & Ports set without analog settings set to digital
3. Toggle would not work without setting the analog stuff to digital, but when properly set it did.
it otherwise would go high and stay high.

Test chip 16F690 on Microchip demo board
Interesting, Since Both posters are using portA in their examples I think some analog register is blocking it working.
Which is what Mackrackit alluded to in post #3, I found it interesting it did not affect #2 in my test.
HTH
JS