SOLVED - PIC seems to RESET unless I add a PAUSE in Mainloop

[Demon]

PIC 16F18877

#CONFIG
    __config _CONFIG1, _FEXTOSC_OFF & _RSTOSC_HFINT32 & _CLKOUTEN_OFF & _CSWEN_OFF & _FCMEN_ON
    __config _CONFIG2, _MCLRE_ON & _PWRTE_OFF & _LPBOREN_OFF & _BOREN_ON & _BORV_LO & _ZCD_OFF & _PPS1WAY_OFF & _STVREN_ON & _DEBUG_OFF
    __config _CONFIG3, _WDTCPS_WDTCPS_11 & _WDTE_ON & _WDTCWS_WDTCWS_7 & _WDTCCS_LFINTOSC
    __config _CONFIG4, _WRT_OFF & _SCANE_available & _LVP_OFF
    __config _CONFIG5, _CP_OFF & _CPD_OFF
#ENDCONFIG

DEFINE OSC 32

ANSELA = %00000000
ANSELB = %00000000
ANSELC = %00000000
ANSELD = %00000000
ANSELE = %00000000

TRISA = %00000000
TRISB = %00000000
TRISC = %00000000
TRISD = %00000000
TRISE = %00001000

LEDblink            var PORTD.0

    PAUSE 200
    LEDblink = 0

Mainloop:
    LEDblink = 1
'    PAUSE 1
    LEDblink = 0
'    PAUSE 1
  GOTO Mainloop
end

Any idea why it seems to reset unless I have a PAUSE 1 in Mainloop?

The trace is on LEDblink pin.




I had this PIC working a while ago. I don't see what I'm missing.

[Demon]

Yeah, had Port instead of Lat.

https://www.picbasic.co.uk/forum/sho...s-the-mainloop


I switched this to WDTE=OFF and it no longer resets.

(have some reading to do on WDTE)

[Ioannis]

Normally Watchdog is reset within the code PBP produces.

But why it does not in the case of 16F18877 seems strange. Maybe it is not controlled correctly?

Ioannis

[Demon]

I have no clue.

My PIC is either ON or OFF, I have no Sleep mode.

https://ww1.microchip.com/downloads/...Doc/31026a.pdf

During normal operation, a WDT time-out generates a device RESET. If the device is in SLEEP mode, a WDT time-out causes the device to wake-up and continue with normal operation, this is known as a WDT wake-up. The WDT can be permanently disabled by clearing the WDTE configuration bit.

[Ioannis]

What is the duration of this reset, if it is reset?

You may add a PAUSE 1000 at the beggining of the program and see if this duration is increased. This will confirm that PIC is indeed reseting.

Ioannis

[richard]

It is definitely a reset, a look at the lst file shows that the looped code segment has no pbp statements in it that generate a clwdt instruction

that loop does the the same thing for every pic chip i tried. its not really a practical loop more a curiosity

[Demon]

I was testing a new breadboard layout and PIC config; to make sure I had a heartbeat before piling more code.

[Ioannis]

Since on power up the SEN bit of the WDTCON0 register is at 0 (Watchdog disabled), why does that chip resets itself?

Ioannis

[HenrikOlsson]

Because if the WDTE bits in CONFIG3 is anything but 0b01 the SEN bit is ignored and the CONFIG block of the code contains _WDT_ON which, according to the .INFO file for the device means

 _WDTE_ON	    ;WDT enabled regardless of sleep; SWDTEN ignored

If you want software control of the WDT you could choose

_WDTE_SWDTEN	    ;WDT enabled/disabled by SWDTEN bit in WDTCON0

/Henrik.

[Ioannis]

But then I see no way that PBP is aware of that or can reset the WDT.

Ioannis

[Demon]

But then I see no way that PBP is aware of that or can reset the WDT.

Ioannis

I would guess by this bit?

When the WDTE bits of Configuration Words are set to ‘01’, the WDT is controlled by the SEN bit of the WDTCON0 register.

(p. 163 of datasheet)

[HenrikOlsson]

Basically the CONFIG settings allows you to force the WDT either on/off OR allow the program to turn it on/off at runtime.

As for resetting/clearing it, as long as you don't DEFINE NO_CLRWDT 1 PBP will clear/reset the WDT by inserting CLRWDT instructions into the code - it doesn't matter if the WDT is actually enabled, disabled, running or not. The instructions will be embedded in the assembly listing of the program. Unless, apparently, you do this kind of super tight loop.