output_high automatically reverting on next output_high

[Daniel Hirschybar]

Hi All,

I am a beginner, and running into a seemingly simply issue:

The description:

I'm using a pic F877. If I set pin D2 HIGH, give it a delay of say 1 sec, and then set pin D3 HIGH, it will automatically turn pin D2 LOW or OFF without my specifying it.

Lets say I want to have 3 pins to remain HIGH permanently (or at least whenever I want them to remain on). This problem is ensuring that I can only have one pin high at a time.

Things I've tried:

#use standard_io(A-E) makes no difference.
SET_TRIS_A-E(0x00) makes no difference
ouput_d(0b00000100);
ouput_d(0b00001100);
Also does the same thing.

Anyway, any suggestions would be absolutely welcome! I am truly stumped.

Thanks in advance!

Daniel

Heres my current VERY SIMPLE TESTING PROGRAM:

#include <16F877.h>
#fuses XT,WDT,NOPROTECT

#use delay (clock=4000000)

main()
{
setup_wdt(WDT_2304MS); /*unneccessary - but here it is*/
output_high(PIN_D4);
delay_ms(250);
output_low(PIN_D4);

set_tris_d(0x00);
output_low(PIN_D2);
output_low(PIN_D3);
while (TRUE)
{
restart_wdt();
output_high(PIN_D2);
delay_ms(250);
output_high(PIN_D3);
delay_ms(250);
}
}






___________________________
This message was ported from CCS's old forum
Original Post ID: 13300

[PCM programmer]

:=Hi All,
:=
:=I am a beginner, and running into a seemingly simply issue:
:=
:=The description:
:=
:=I'm using a pic F877. If I set pin D2 HIGH, give it a delay of say 1 sec, and then set pin D3 HIGH, it will automatically turn pin D2 LOW or OFF without my specifying it.
------------------------------------------------------

1. What happens if you comment out all the Watchdog timer stuff.
(including changing the fuse to NOWDT) Does it still do this ?
I'm trying to find out if it's some problem with the ports, or
if it's caused by the WDT.

2. Also, you should add NOLVP to the end of your #fuses, unless
you know for certain that you're using low voltage programming.

3. What's your version of the compiler ? There once was a
problem with TRIS on ports D and E. See the following line
from the old CCS versions page:
3.052 SET_TRIS_D and E were broke in 3.050,3.051 now restored

4. Do have you anything connected to these Port D pins, such
as LEDs, without a series resistor ? (just wondering).
___________________________
This message was ported from CCS's old forum
Original Post ID: 13301

[Rainer]

Is the connection to the ground o.k.?
Is your power supply o.k.?
___________________________
This message was ported from CCS's old forum
Original Post ID: 13306