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Christophe
Joined: 10 May 2005
Posts: 323
Location: Belgium
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| don't want the WATCHDOG to reset, but it does! |
 Posted: Mon Jun 27, 2005 7:46 am |
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| Code: | | #fuses XT, NOPUT,WDT, NOPROTECT, NOLVP, NOCPD, NOWRT, NOBROWNOUT |
| Code: |
//*********************************** Main ***********************************//
void main()
{
int8 i,temp;
int16 key;
int1 Pressed, Alles_los, signaal_gegeven = FALSE;
char buffer[9];
Zoemer_aan = TRUE;
setup_wdt(WDT_2304MS);
setup_adc_ports(NO_ANALOGS); // ADC UIT
setup_adc(ADC_OFF);
SETUP_TIMER_1(T1_DISABLED); // T1 uit
SETUP_TIMER_2(T2_DISABLED,0,1); // T2 uit
setup_psp(PSP_DISABLED); // PSP UIT
setup_comparator(NC_NC_NC_NC);// COMPARATOR UIT
setup_vref(FALSE);
enable_interrupts(INT_RDA);
enable_interrupts(INT_EXT);
enable_interrupts(GLOBAL);
output_High(BR_SLEEP);
output_high(E3_uit); // E3-Lijn op hoog plaatsen
output_low(BUZZ); // Buzz laag
//Batterijspanning controleren; indien te laag: niet opstarten.
do
{
Meet_Vbat(&Vbat);
restart_wdt();
if (Vbat < 3.5 && !signaal_gegeven)
{
//LOW_BAT_WARNING();
restart_wdt();
BUZZER();
signaal_gegeven = TRUE;
}
}
while (Vbat < 3.5 ); |
In main, I'm first checking the battery voltage; if it's too low, the pic just doesn't fire up. if it's good, the program begins to run.
Now I have touse the watchdog to get me out of sleep_mode. Because when the device is in sleep, the battery voltage also has to be monitored.
Now is on this code, the pic continuously reseting! I don't want that, I want it to buzz 1 time and stay looping until Vbat is good..
suggestions?
** Is there another way to wake up from sleep to check the battery voltage instead of the watchdog?
** The watchdog wakes the PIC up every 2300MS. How can I prolongue this time? If I want to check the battery voltage every minute for instance.
Many thanks |
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newguy
Joined: 24 Jun 2004
Posts: 1908
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Christophe
Joined: 10 May 2005
Posts: 323
Location: Belgium
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| Posted: Mon Jun 27, 2005 8:26 am |
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| I checked that; doesn't help me ... sorry, I don't understand why the PIC is reseting!? |
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Guest
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| Posted: Mon Jun 27, 2005 9:37 am |
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| setup_wdt(WDT_OFF); |
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Guest
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| Posted: Mon Jun 27, 2005 9:41 am |
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| you must wake up evey 2sek and reset wdt |
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treitmey
Joined: 23 Jan 2004
Posts: 1094
Location: Appleton,WI USA
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| Posted: Mon Jun 27, 2005 10:43 am |
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If you don't know why the PIC is reseting then use the restart_cause()
function at the START of main to print why. Use info from the header file for the chip to decrypt the number returned. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon Jun 27, 2005 11:57 am |
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Make a small test program to experiment with the Watchdog Timer
in Sleep mode, until you understand it completely.
If you still can't make it work, then post a small but complete
test program, including the #fuses, #include, and #use delay()
statements. |
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ckielstra
Joined: 18 Mar 2004
Posts: 3680
Location: The Netherlands
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| Posted: Mon Jun 27, 2005 2:00 pm |
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Just some thoughts:
1) You are restarting the watchdog after Meet_Vbat() and directly again before BUZZER(), so the second iteration has a total time of these two functions before restarting the watchdog again. How much time do the functions Meet_Vbat and BUZZER take together?
2) The CCS define WDT_2304MS gives the impression of being very accurate, but on most PIC devices the watchdog is specified with approximately a 50% margin. You didn't mention your processor type, but for example on the PIC16F688 the watchdog is typical 17ms, with a minimum of 10ms and a maximum of 30ms. Suppose your chip has the minimal value, then the watchdog doesn't trigger after 2304ms, but after 1280ms. Have you accounted for this? |
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newguy
Joined: 24 Jun 2004
Posts: 1908
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| Posted: Mon Jun 27, 2005 3:47 pm |
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| Christophe wrote: | | I checked that; doesn't help me ... sorry, I don't understand why the PIC is reseting!? |
The reason why it resets is that the PIC always, upon wakeup caused by the watchdog, starts the program anew. FROM THE BEGINNING.
That's why, in my example, I look for the cause of the restart, and act accordingly.
Look again, read it, try to understand it. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon Jun 27, 2005 4:15 pm |
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| Quote: |
The reason why it resets is that the PIC always, upon wakeup caused by
the watchdog, starts the program anew. |
That's not true if the PIC is in sleep mode. From the 18F452 data
sheet, in the section on Special Features of the CPU/ Watchdog Timer:
| Quote: |
During normal operation, a WDT time-out generates a
device RESET (Watchdog Timer Reset). If the device is
in SLEEP mode, a WDT time-out causes the device to
wake-up and continue with normal operation (Watch-dog
Timer Wake-up). |
There are also lots of little "gotchas" in sleep mode wakeup
with regard to interrupts and the watchdog. That's why I asked
him to do a test program. From the data sheet:
| Quote: | To ensure that the WDT is cleared, a CLRWDT instruction
should be executed before a SLEEP instruction. |
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newguy
Joined: 24 Jun 2004
Posts: 1908
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| Posted: Mon Jun 27, 2005 4:24 pm |
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| PCM programmer wrote: | | Quote: |
The reason why it resets is that the PIC always, upon wakeup caused by
the watchdog, starts the program anew. |
That's not true if the PIC is in sleep mode. From the 18F452 data
sheet, in the section on Special Features of the CPU/ Watchdog Timer:
| Quote: |
During normal operation, a WDT time-out generates a
device RESET (Watchdog Timer Reset). If the device is
in SLEEP mode, a WDT time-out causes the device to
wake-up and continue with normal operation (Watch-dog
Timer Wake-up). |
There are also lots of little "gotchas" in sleep mode wakeup
with regard to interrupts and the watchdog. That's why I asked
him to do a test program. From the data sheet:
| Quote: | To ensure that the WDT is cleared, a CLRWDT instruction
should be executed before a SLEEP instruction. |
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PCM,
Then why does my little test program always do a fresh start every time the watchdog wakes it up?
To be honest, when I did that little test program (mainly as a learning exercise for myself), I couldn't figure out why the pic kept resetting, when the data sheet said that it shouldn't.
The only way I could get it to behave as it should (or as I thought it should) was to code the program the way I did. My conclusion was that the watchdog was doing a fresh restart every time. |
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sseidman
Joined: 14 Mar 2005
Posts: 159
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| Posted: Mon Jun 27, 2005 6:16 pm |
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| newguy wrote: |
Then why does my little test program always do a fresh start every time the watchdog wakes it up?
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Might be because you have no infinite loop at the end of your code if the battery voltage is good!
Scott |
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newguy
Joined: 24 Jun 2004
Posts: 1908
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| Posted: Mon Jun 27, 2005 7:36 pm |
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| sseidman wrote: | | newguy wrote: |
Then why does my little test program always do a fresh start every time the watchdog wakes it up?
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Might be because you have no infinite loop at the end of your code if the battery voltage is good!
Scott |
Scott,
You're confusing me with someone else. My code doesn't check for battery voltage, and it does have an infinite loop at the end of main.
A link to my code: http://www.ccsinfo.com/forum/viewtopic.php?t=22952&highlight=sleep
It goes to sleep, the watchdog wakes it up, and it starts fresh with every watchdog timeout.
I'd like to know what I'm missing. |
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PCM programmer
Joined: 06 Sep 2003
Posts: 21708
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| Posted: Mon Jun 27, 2005 7:57 pm |
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Here is a demo program for wake-up from Sleep by the watchdog timer.
I tested this with PCH vs. 3.188 on a PicDem2-Plus board.
It displays the following output in the terminal window:
| Quote: |
Start
Sleep
Wake up
Sleep
Wake up
Sleep
Wake up
etc. |
| Code: | #include <18F452.H>
#fuses XT, WDT, NOPROTECT, BROWNOUT, PUT, NOLVP
#use delay(clock = 4000000, restart_wdt)
#use rs232(baud=9600, xmit=PIN_C6, rcv=PIN_C7, restart_wdt, ERRORS)
void main()
{
printf("Start\n\r");
while(1)
{
printf("Sleep\n\r");
restart_wdt();
sleep(); // Go to sleep and wait for WDT to wake-up
printf("Wake up\n\r");
delay_ms(500);
}
} |
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newguy
Joined: 24 Jun 2004
Posts: 1908
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| Posted: Mon Jun 27, 2005 9:39 pm |
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PCM,
Thanks, that gives me a new approach to try.
-- Mark |
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