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freedom
Joined: 10 Jul 2011
Posts: 54
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| Timing problem, Need help, please survive |
 Posted: Fri Aug 05, 2011 8:27 am |
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Hi there.
I am new in PIC programming.
I've made a project but do not working properly
When LED 1 is active, LED 2 is not On until the delay time is over.
But I need to turn on the LED2 before the delay time. How can I do this ?
Actually I want to keep on LED1 for three or five minutes/seconds and during this time I want to execute other instruction of my program.
I post here the code so that you can understand how much I know and what I want to do.
Need your help.
My code as follows:
| Code: |
#include <16F877A.H>
#fuses XT, NOWDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock = 4000000)
#include <flex_LCD420.c>
//===================================
void main()
{
// The lcd_init() function should always be called once,
// near the start of your program.
lcd_init();
// Clear the LCD.
printf(lcd_putc, "\f");
delay_ms(50);
printf(lcd_putc, "\f PIC Experiment");
printf(lcd_putc, "\n--------------------");
printf(lcd_putc, "\nBatch Total ");
while(1)
{
if (!input(pin_D0))
{output_high(pin_C0);
delay_ms(15000); // keep the LED1 on for this time
output_low(pin_C0);}
if (!input(pin_D1))
{output_high(pin_C1);} // to active another LED2
if (!input(pin_D2))
{output_low(pin_C1);}
}
} |
Last edited by freedom on Sun Aug 07, 2011 1:14 pm; edited 2 times in total |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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| timer ints are your friend |
| Posted: Fri Aug 05, 2011 9:47 am |
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So long as you are not going to do any RS-232 in software
you should investigate using timer #1 counting the master clock
and generating INTerrupts to decrement a 'tick' timer that will
tell you precisely when any amount of time has elapsed and
direct your LED actions with a simple flag var or state machine variable -
that is altered when the background timer count has elapsedl
Then you go about your business w/ using the delay function
which you rightly observe - locks you in place .... waiting. |
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freedom
Joined: 10 Jul 2011
Posts: 54
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| Posted: Fri Aug 05, 2011 10:07 am |
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Thnx a lot asmboy.
Would you like to provide code example regarding on my problem.
I don't know how to use timer.
Thanks to all and waiting for your reply. |
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asmboy
Joined: 20 Nov 2007
Posts: 2128
Location: albany ny
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| Posted: Fri Aug 05, 2011 12:08 pm |
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This is a quick combined hack from several other programs but it shows the basic ideas for a simple non interrupt way to do this. You can adjust the setup of timer0 to get a convenient 10ms or and many other tick granularities.
| Code: |
unsigned int16 MSecs=0;
// polled non interrupt way to get 1ms accuracy w/o using delay_ms
// part of your init
setup_timer_0 (RTCC_DIV_4 );
// at 4 mhz sec /tick we need to preload the counter with '6'
// to get the best 1msec /tick accuracy
//
// this will initiate the delay in millisecs you want
// call it like setdelay(1000) ; for 1 second delay etc
//
void setdelay(unsigned int16 howmanyms ){
msecs=howmanyms; // will cancel any partially completed delay too
set_timer0(6); // compensate to get pretty exact 1 msec
T0IF=0; // cancel OVF flag
}
void myeventhandler(void ){
// ** where you do your led on off logic or
// ** any other timer/delay , based event
// ** this is your state machine handler function
}
// this will implement a POLLED 1 ms 'tick' using timer 0
// with a max range of 65.535 seconds
// it is POLLED method in main
// add this section to your code
//
void main(void){
// your init code
while (1) // loop forever below here
// ** ----------------------
// your other code you want to loop thru and poll
// but note: any code execution that takes more than 1 msec
// will stretch your delay --
// ** ----------------------
// now the timer minder
//
if (MSecs && T0IF) {
set_timer0(6);
T0IF=0; // kill OVF flag
--MSecs; // 1 ms recurrent decrement
if ( !MSecs) myeventhandler();
}
}
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freedom
Joined: 10 Jul 2011
Posts: 54
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| Posted: Fri Aug 05, 2011 2:38 pm |
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Thnx a lot asmboy.
Sorry to say, still now I'm not clear. I've read CCS manual but I'm not really clear.
As I'm new in Programming PIC, so I've to disturb. Sorry for this.
If you see my code then you understand that first I turn on a LED and it will 'on' for mentioned time as i use delay_ms. But in this case other instruction doesn't execute until the delay time is over.
Hope, you would be kind enough to modify my code so that i can understand. |
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Ttelmah
Joined: 11 Mar 2010
Posts: 19546
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| Posted: Sat Aug 06, 2011 9:42 am |
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This is the point about 'single threaded' applications. The same would happen on a PC, if you used a delay like this. Basically while doing one job, the code waits for each thing in that job.
Asmboy, has posted a way round this.
This is not a CCS question. You need to go away, and do some basic learning about how to do a task like this, and then come back to ask about the details of how to do this in CCS (there are three basic ways, the polling method shown by Asmboy, using a 'tick' interrupt - this is how you would probably do it on a PC - , or using the RTOS).
This forum is for specific things to do with CCS, _not_ 'how to program'. You need to do some basic learning first.
Best Wishes |
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freedom
Joined: 10 Jul 2011
Posts: 54
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| Posted: Sat Aug 06, 2011 10:06 am |
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thanx Ttelmah
Sorry to say I'm very hopeless on your remark.
However, I'm in such place where is no teacher than can help me to understand. Only this forum and other internet based resources can help me.
As your attention, please remember a little example makes a man can solve a big problem.
I just expect a little example code that can help me to understand the procedure.
Hope you understand.
Thanks for reply |
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freedom
Joined: 10 Jul 2011
Posts: 54
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| Posted: Mon Aug 08, 2011 3:06 pm |
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| still now I'm waiting |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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