I don't think I have a clear understanding of what you are doing, but let
me see if this is close.

It sounds like you need an interrupt service routine that hits every 10
milliseconds, that does

PORTB=PAT[i];

meanwhile, it also needs to increment i on every interrupt, and test
whether I is > 240, in which case it will do something else (what I am not
sure).

Setting up the timer will depend on your system, I'll leave that up to
you.  You'll have to enable the interrupts for that timer, and figure out
how to get it to interrupt every 10 ms.  You will probably have to stuff a
number into the timer counter register at the end of every interrupt
service routine to get this to work.  Considering there may be some
overhead due to the C compiler's context saving routine, I would simulate
this to make sure that you have the "magic numbers" correct.  I haven't
ever been able to calculate these to an accuracy that satisfied me.

I am assuming you are using Hitech C?

So your interrupt routine might look like this:


void interrupt int_handler(void){

if (TMR1IF){    // Test if it was a timer1 interrupt  (assuming you use
timer1)
        TMR1IF = 0;

        if(i++ > 240){
                i = 0;
        }

        PORTB=PAT[i];

        if(PORTB==0x55){
                .. whatever needs to be done here- I don't quite
understand  it.
        }

        TIMER1H = MAGIC_NUMBER_#1  // calculate these and then simulate
them to see if you have them right.
        TIMER1L = MAGIC_NUMBER_#2

}

Meanwhile your main program can be very trivial.  If you have nothing else
to do then it could even be:

main{
... Setup and initialization code

do{

}while(1);

}


-- Lawrence Lile






Andre Abelian <engelec@EARTHLINK.NET>
Sent by: pic microcontroller discussion list <PICLIST@MITVMA.MIT.EDU>
03/04/2003 06:54 PM
Please respond to pic microcontroller discussion list


        To:     PICLIST@MITVMA.MIT.EDU
        cc:
        Subject:        [PIC]: Generating 5 pulses at the same time


Hi to all,
Apologies if the tag isn't right for c code:

In this code I used 240 byte of data to be cycled
I need to make Rb1 high 8 time but duty cycle to be 3 times
Smaller then other pulses. Only RB1 needs to be like that
My question is how do I do that without interrupting main
Array my guess is I have to use interrupt in background
I think it called (ring loop)or some thing  any help
Will appreciate.

Andre




/*##################################################
# pic18f452:
# Hardware info:
# portb,0= will gen 16x8=128 pulses per rev
# portb,1= will gen 8 pulses per rev
# portb,2= will gen 4 pulses per rev
# portb,3= will gen 4 pulses per rev
# portb,4= will gen 4 pulses per rev
# cyl_1=0B00000001
# cyl_2=0B00000101
# cyl_3=0B00001001
# cyl_4=0B00001101
# cyl_5=0B00010001
# cyl_6=0B00010101
# cyl_7=0B00011001
# cyl_8=0B00011101
####################################################
*/
#include <pic18.h>
#include "delay.c"
#define PORTBIT(adr, bit)       ((unsigned)(&adr)*8+(bit))
#define XTAL_FREQ 4MHZ

static bit      led  @  PORTBIT(PORTB, 7);

// function decaration
void port_init(void);
void run();

// main program
void main(void)
{
    port_init();        // setup port
    run();
}

// main program
void run(){
unsigned char c;
unsigned char i=0;
unsigned char const
PAT[]={0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,

0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,

0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,
                           0B00000101,

0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,

0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,
                           0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,
                           0B00001001,

0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,

0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,
                           0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,
                           0B00001101,

0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,

0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,
                           0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,
                           0B00010001,

0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,

0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,
                           0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,
                           0B00010101,

0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,

0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,
                           0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,
                           0B00011001,

0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,

0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,
                           0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,
                           0B00011101,

0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,

0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,

0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x01,0x00,0x55};

for(c=0;c<240;c++){       // setup count 128
PORTB=PAT[i];            // read the table and display it
DelayBigMs(10);
if(PORTB==0x55){
break;} // see if it passed over 0x55 last array (not used)
i++;
}
}

// Port Init
void port_init(void){
    TRISB=0; // set portb output
         TRISA=0xFF; // set porta all input
         PORTB=0; // make sure all leds off
         }

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