Strange problem with an 18F4580 based project

[malc-c]

Darrel, just checked the hardware file and these are the settings

ASM 
  __CONFIG    _CONFIG1H, _OSC_HSPLL_1H
  __CONFIG    _CONFIG2L, _PWRT_ON_2L  
  __CONFIG    _CONFIG2H, _WDT_ON_2H & _WDTPS_512_2H
  __CONFIG    _CONFIG3H, _PBADEN_OFF_3H
  __CONFIG    _CONFIG4L, _LVP_OFF_4L & _XINST_OFF_4L
ENDASM

If I read that then the WDT is running, and as I've not inserted DEFINE NO_CLRWDT 1 into the code then I assume that PBP has automatically inserted the resets through the code automatically. However on checking the corresponding asm file there are just the following references to CLRWDT in that file (towards the beginning)

;---[Add an Interrupt Source to the user's list of INT Handlers]--------------
INT_Handler  macro  IntFlagReg, IntFlagBit, Label, Type, Reset
  list
    local AfterSave, AfterUser, NoInt
INT_Count += 1
PrList#v(INT_Count)R = IntFlagReg
PrList#v(INT_Count)B = IntFlagBit
PrList#v(INT_Count)Priority = Priority
        GetIntInfo   IntFlagReg, IntFlagBit
        if (Found == YES)
            btfss    INT_Enable_Reg, INT_Enable_Bit, 0  ; if INT is enabled
            goto   NoInt
            btfss    INT_Flag_Reg, INT_Flag_Bit, 0      ; and the Flag set?
            goto     NoInt
            if (Priority == H)
                bsf      _Serviced_H, 0
            else
                bsf      _Serviced_L, 0
            endif
            ifdef NO_CLRWDT
                if  (NO_CLRWDT != 1)
                    CLRWDT
                endif
            else
                CLRWDT
            endif
                
            if (Type == PBP)                         ; If INT handler is PBP
              if (Priority == H)
                ifdef ReEnterHPused
                    GetAddress21  AfterSave, RetAddrH  
                    L?GOTO  _SavePBP_H        ; Save PBP system Vars in HP INT
                else
    error "ReEnterPBP-18 must be INCLUDEd to use High Priority PBP interrupts"
                endif
              else ; Priority = L
                ifdef ReEnterLPused
                    GetAddress21  AfterSave, RetAddrL  
                    L?GOTO  _SavePBP_L        ; Save PBP system Vars in LP INT
                else
   error "ReEnterPBP-18LP must be INCLUDEd to use Low Priority PBP interrupts"
                endif
              endif
            endif

I've searched for info on using the watchdog timer and came across Mel's post in 2003 ??? which helps explain how PBP uses the timer... but still a bit confused given the complexity of our code

[Darrel Taylor]

To see where the CLRWDT instructions are inserted, you would have to look at the .LST file because they are part of the library, not the generated .ASM code.

The one's you found are part of DT_INTS, and as you can see they also respond to the NO_CLRWDT define.

The base period of the WDT on a 4580 is 4ms, and with a postscaler of 512 it will timeout after about 2 seconds.

Your main loop will take less than 2 seconds each time so a single CLEARWDT statement at the end of the loop just before GOTO Main should suffice, although it may be advantageous to put it in the area where it updates the heater drives just to be sure that is getting accomplished. But then if you turn off power to all 4 channels, you'll have to clear it somewhere else or it will reset every 2 seconds. You may just have to play with it and see what works best.

            IF ChannelPWR(pid_Channel) THEN
                HeaterDrives(pid_Channel) = pid_Out
                CLEARWDT
            ELSE
                HeaterDrives(pid_Channel) = 0
            ENDIF

HTH,

[malc-c]

The base period of the WDT on a 4580 is 4ms, and with a postscaler of 512 it will timeout after about 2 seconds.

Your main loop will take less than 2 seconds each time so a single CLEARWDT statement at the end of the loop just before GOTO Main should suffice,

Darrel,

I've added DEFINE NO_CLRWDT 1 at the start of the code along with other defines. Then added one CLEARWDT just before the GOTO MAIN -

Just before the main loop the code jumps to a simple section that displays the current version

about:
    LCDOUT $FE,2,"   Multi - Therm    "
lcdout $FE, $C0, "    Thermostat      "

lcdout $FE, $D4, " Firmware Ver 4.60  "
Pause 2000
LCDOUT $FE,1
goto main

No with the CLEARWDT inserted as suggested the code is constantly displaying the about screen. IE its constantly resetting which looking at the pause 2000 line in the about the same as the WDT.

So I commented out the GOTO About and the program ran fine, however if I jump to the main menu it quickly resets before you get chance to make any changes. So I guess I have to go through each section of the code to ensure that I insert enough CLEARWDT statements to allow the program to function, but not defeat the purpose of the WDT ?

[Darrel Taylor]

Yup, that's part of that "strategically" idea.

And now you will appreciate the idea of "Event Driven" software, instead of GOSUB somewhere then return when it's finished, whenever that is.

With event driven, everything keeps running, even if you're moving through menu's on an LCD.

Keep in mind that if your light bulb spark is causing a false button press and it's going off into one of those routines ... the WDT won't help unless that routine times out eventually because now you've added CLEARWDT's to it.

[malc-c]

Yup, that's part of that "strategically" idea.

And now you will appreciate the idea of "Event Driven" software, instead of GOSUB somewhere then return when it's finished, whenever that is.

With event driven, everything keeps running, even if you're moving through menu's on an LCD.

Keep in mind that if your light bulb spark is causing a false button press and it's going off into one of those routines ... the WDT won't help unless that routine times out eventually because now you've added CLEARWDT's to it.

Yeah, having to work through the sub-routines to add the CLEARWDT so that it doesn't reset, but then to add some form of time out routine so that if nothing is pressed it returns to the main menu.

I must admit my old brain finds it comfortable with the goto / gosub way of coding... the "if button pressed gosub xyz", and I wouldn't know how to re-work the code for event driven routines... still learning ! I'll keep plodding away through the code to insert the CLEARWDT hear and there, at least it will provide some form protection.