How to write the long delay code ???

[engkiang]

Hi All,
I'm newbies on programming in PIC C, I'm looking some help on creating the code that looping two tasks where one task will be execute after 3 days, another one task will be execute after 3 hours. The ideal like below:

Loop3d:
Reach to 3 days?
no, go to Loop3d.
yes, set the portA to high.

Loop3h:
Reach 3 hours?
no, go to Loop3h
yes, set portA to low

go to Loop3d

Thanks.

[ABSF]

CODE: SELECT_ALL_CODE

Loop3d:
Reach to 3 days?
no, go to Loop3d.
yes, set the portA to high.

Loop3h:
Reach 3 hours?
no, go to Loop3h
yes, set portA to low

go to Loop3d


In that case you 3-hour delay would only be run after 3 days. Something is wrong in your flowchart. It should be like this

CODE: SELECT_ALL_CODE

Main():
call Loop3d
call Loop3h
Loop back to Main()

Loop3d:
Reach to 3 days?
no, go to Exit1
yes, set the portA to high.
Exit1: return to calling program

Loop3h:
Reach 3 hours?
no, go to Exit2
yes, set portA to low
Exit2:return to calling program

The best way to do long delay is to use a RTC (Real Time Clock)

Allen

[engkiang]

Thanks Allen.

Kindly describe on how to use the RTC for this type of delay. Any ideal code and information that related to this can be refer?
Thanks again.

[ABSF]

First you have to understand what is a real time clock. The easiest way is to download the datasheet of DS1307 from internet. Then learn how to interface it to your PIC. You can also refer to the cytron PR12 here:

http://www.cytron.com.my/viewProduct.php?pid=EAo4Mh0xEQsqEzAxLi8yKqD/6h4wOeifVdvOuCrCnwY=&store=

I am not telling you to make the clock but to refer to the schematics and sample code to understand how it works and how to make use of it in your project. This chip is very popular and is very small like LM555. To interface to MCU only needs 2 or 3 wires.

After reading if you still have any problem, you can always post your questions here.

Allen

[shahrul]

This is example code for DS1307.

On the example, have this code

CODE: SELECT_ALL_CODE

   if(sec%5==0) LCD_LIGHT=0;
   else LCD_LIGHT=1;


This is example to execute some instruction every 5 seconds. You must try yourself to do loop 3 hours or 3 days.