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pic24FJ and wdt confused

 
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ciccioc74



Joined: 23 Mar 2010
Posts: 30

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pic24FJ and wdt confused
PostPosted: Thu Feb 11, 2021 12:50 pm     Reply with quote

Hi everyone. I am trying to set the wdt for PIC 24FJ1024GB610 with
Code:
#use delay(crystal=8000000,clock=32000000 )

I read the datasheet and the DS39697B but i just can't get it to work.
If I understand correctly I can enable WDT from HW or SW.
So if I write
Code:

#FUSES WDT_SW

and then
Code:

setup_wdt(WDT_ON |WDT_2S);

The PIC should restart every 2S unless I write
Code:
restart_wdt

if I want to use the wdt HW I enable
Code:
WDTCLK_31KHZ
#FUSES WDT
#FUSES WPOSTS12

So i should have a wdt every 2.048 sec
Where am I wrong?
Ttelmah



Joined: 11 Mar 2010
Posts: 19195

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PostPosted: Thu Feb 11, 2021 1:04 pm     Reply with quote

If that is the same as another chip that was posted recently, you don't
want to OR the entries for setup_wdt. Just use:


setup_wdt(WDT_2S);

and

setup_wdt(WDT_OFF); when you want to turn it off.

The value used for ON/OFF, is 0/1, and these are separate commands,
not values that can be OR'ed into the time,

They are careful to say when values can be ORed. This is not a place
where they can be.

The setup_wdt(WDT_2S); setting, automatically sets the clock and
postscaler. Then ON or OFF starts/stops it when needed. Using this
anywhere in the code results in the fuses being set to match this time.
ciccioc74



Joined: 23 Mar 2010
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PostPosted: Thu Feb 11, 2021 1:21 pm     Reply with quote

Thanks Ttelmah
I had already done this test but I do not reset the micro. With other PIC of this project no problem (18f and 32MX) but it doesn't work here.
CCS rev 5.071 with MPLAB
only
Code:
#FUSES CKSFSM                   //Clock Switching is enabled, fail Safe clock monitor is enabled
#FUSES BROWNOUT               //No brownout reset
#FUSES NOJTAG 
#use delay(crystal=8000000,clock=32000000 )
 


and in main:
Code:

setup_wdt(WDT_2S);
Ttelmah



Joined: 11 Mar 2010
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PostPosted: Fri Feb 12, 2021 1:54 am     Reply with quote

Add as a separate line:

setup_wdt(WDT_ON);

The point is that you can't 'OR' the operations as you are trying to do.
setup_wdt(WDT_2S);
makes the compiler setup the fuses for the required time.

Then:

setup_wdt(WDT_ON);

actually enables it,
and:

setup_wdt(WDT_OFF);

disables it.

They two things cannot be OR'ed together into one line. They have
to be separate lines.
ciccioc74



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PostPosted: Fri Feb 12, 2021 11:17 am     Reply with quote

I am only writing to communicate that I have not solved the problem with the WDT. I used a Work Around If i receive a data from slaves i reset a counter otherwise the counter increments every second
Code:
 if(contWDT_1>15 && contWDT_2>15 && contWDT_3>15 && contWDT_4>15){
             reset_cpu();
         }
Ttelmah



Joined: 11 Mar 2010
Posts: 19195

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PostPosted: Fri Feb 12, 2021 12:51 pm     Reply with quote

I have to ask a question. How are you testing this?.

You do realise that the watchdog does not work in an ICD?.

I just tried a test:
Code:

#include <24FJ1024GB610.h>
#device ICSP=1
#use delay(clock=32000000,crystal=8000000)

#FUSES WDT_SW                   //Watchdog timer available
#FUSES CKSFSM                   //Clock Switching is enabled, fail Safe clock monitor is enabled
#FUSES NOBROWNOUT               //No brownout reset
#FUSES NOJTAG                   //JTAG disabled

#PIN_SELECT U1TX=PIN_B0
#PIN_SELECT U1RX=PIN_B1
#use rs232(UART1, baud=9600, stream=SERIAL1, ERRORS)

void main()
{
   int8 reason;
   //Basic WDT test
   reason=restart_cause();
   
   //Start by printing a message on boot
   delay_ms(100);
   if (reason==RESTART_WATCHDOG)
      fprintf(SERIAL1,"Watchdog restart\n");
   else
      fprintf(SERIAL1,"Boot\n");
   setup_wdt(WDT_2S); //This actually sets the fuses for you

   while(TRUE)
   {
      delay_ms(2500);
      //If we get here the watchdog has not triggered.
      fprintf(SERIAL1,"No watchdog\n");     
   }
}


and it merrily prints:

Boot
Watchdog restart
Watchdog restart
....

I hadn't got 5.071, so used 5.072.
temtronic



Joined: 01 Jul 2010
Posts: 9081
Location: Greensville,Ontario

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PostPosted: Fri Feb 12, 2021 4:06 pm     Reply with quote

re:
Quote:
So i should have a wdt every 2.048 sec.

I was curious, looked at the datasheet.....well I think it's the right one...
LPRC is used during sleep and has a +-20% variation of the 31KHz clock.

So I sure hope he isn't counting on 2.048 seconds to be accurate.

Jay
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