Need help with my bits

[shocks]

High Guys
Im not sure whats goin on.
In the code that follows Ive set the register 0x20 the name Phasereg.
I have an ISR for Timer 1. The ISR is meant to check the status of bits 1,2,3 in Phasereg.
I set the value of these bits to 1 in the main code and when I check, they are as i have set them, in the main code. However when the code throws the ISR, the value of the bits appears to have returned to Zero????

The idea behind the code is to tell the ISR which input C2,C3,C4 has lost its input, causing the ISR.


#include <16f877a.h>
#device ICD=TRUE
#fuses HS,NOLVP,NOWDT,PUT
#use delay(clock=20000000)
#use rs232 (DEBUGGER)
#define GREEN_LED PIN_A5
#define YELLOW_LED PIN_B4
#define RED_LED PIN_B5
#define PUSH_BUTTON PIN_A4
#define R_PHASE PIN_C2
#define S_PHASE PIN_C3
#define T_PHASE PIN_C4
#define OUT PIN_C5
#define Phasereg 0x20
#bit rphase=0x20.1
#bit sphase=0x20.2
#bit tphase=0x20.3
#int_timer1

timer1_isr()
{//char phase;
printf("int, Rphase=%u",rphase);
IF(rphase)
{output_LOW(RED_LED);
delay_ms(100);
output_high(RED_LED);
delay_ms(100);}
IF(sphase==1)
{output_LOW(GREEN_LED);
delay_ms(100);
output_high(GREEN_LED);
delay_ms(100);}
IF(tphase==1)
{output_LOW(YELLOW_LED);
delay_ms(100);
output_high(YELLOW_LED);
delay_ms(100);}
}

void main(){

WHILE(1){
output_high(GREEN_LED);
output_high(RED_LED);

setup_timer_1(T1_INTERNAL | T1_DIV_BY_8);
enable_interrupts(INT_TIMER1);
enable_interrupts(GLOBAL);
set_timer1(58661);
//rphase=1;
#asm
movlw 11111111
movwf 0x20
#endasm

//printf("int, Rphase=%u",rphase);

while(!input(R_PHASE));
set_timer1(58661);
sphase=1;
while(!input(S_PHASE));
set_timer1(58661);
tphase=1;
while(!input(T_PHASE));
disable_interrupts(GLOBAL);
(output_low(GREEN_LED));
//delay_ms(100);
}}


I would really appreciate help and/or advice

[PCM programmer]

[MikeW]

and of course, the last thing you want in an isr are delay_ms routines.

it is always best to just use the isr to set and clear semaphore flags, and let a routine in main turn leds on, and have delays.

Mike

[sjbaxter]

You also want to move the

[shocks]

Guys thanks much for the help.
PCM programmers reply is particularily helpful.

Your collective comments on the use of while loops and printf are quite correct. Rest assured Ionly use them for debugging. I find looped code is easier to debug when implemented with hardware.
The printf's give an indication of whats actually happening when used in conjunction with the monitor in debugger.

I dont have a big problem with time constraints in terms of signal input frequency (VLF), hence the ISR contains actual executable code with delays to flash LEDs.

In terms of your collective responses I would be grateful for any insightful code snippets, particularily from Simon.
Thanks once again

[sjbaxter]

First here is your code with a few corrections and improvements:

Note: there is nothing in you code that resets any of the *phase values to zero !!! so this is supposed to be a one-shot application ??

[shocks]

Simon
You're quite correct. Commenting would be better, bad habit on my behalf.
Im new to the forum so I need a small bit of grace.

The project is composed of a number of features, hence the code is written to become part of a bigger code.

The code posted, looks at pins C2 C3 C4 and tests for loss of voltage( ie zero) on a pin by waiting for the pin to go high for 11ms.
The inputs are 3 square waves with a 120 degree phase displacement. The frequency is 50 HZ same as your AC supply in UK.
The 11ms delay which is the count to ISR on T1, is 1 ms longer than half the cycle time.
I start the timer, wait for a high on the pin , if it goes high TI resets and looks at the next pin.
If not, the ISR is called the missing input identified and the relevant LED energised.

Thats all, in theory at least.

I appreciate your help.

Paul

[Neutone]

How about something simple