PIC Microcontoller Methods

Detecting the cause of a Startup

Forceing a hardware reset

Alice Campbell [acampbell at SCSENGINEERS.COM] says:

This one traps WDT, MCLR, Cold boot, warm boot, deliberate timeouts, sleep, and other things.

Reqires a flag register called mflag here. This router dumps all mystery states to the wmbt routine which initializes everything and puts selected registers on the rs232 output line for analysis.

;;
 org     0
 nop
;       goto    top
;       org     0x004
top
 call   init
 CLRF   PORTA
 CLRF   PORTC
 clrf   PORTB
;       clrf    mflag   ;for debugging purposes especially simulator
;parse the big guys
 btfsc   status,TO      ;status,4
 GOTO    TO1            ;to=1 wmbt or startup
 GOTO    TO0            ;to=0 wdt in sleep or wdt

TO0    btfss   status,PD      ;this actually is used
 goto    wmbt           ;to=0 pd=0 reset+clrwdt
 goto    wozat            ;to=0 pd=1 wdt

TO1    btfss   status,PD      ;hello? hello?
 goto    main            ;to=1 pd=1 powerup
 goto    wmbt            ;to=1 pd=0 sleeeeeeeep

;parse out the flags next
;sort of a state machine i guess
wotrst  btfsc   mflag,0         ;mclr+sleeping? not done, dump
        goto    wmbt;zzz           ;decrement lsb of sleep or
continue

t_6      btfsc   mflag,6         ;err goes to dump
        goto    wmbt            ;dont clear this in wmbt
t_7      btfsc   mflag,7         ;decrement sleep loop
        goto    woof
t_0      btfsc   mflag,0         ;main sleep
        goto    zzzz
t_2      btfsc   mflag,2          ; during readout
        goto    mopup            ;restore old address and goto
readlp
t_1      btfsc    mflag,1         ;flag for end of write loop
        goto    disp
t_4      btfsc   mflag,4                ;setup area
        goto    loopw
t_5     btfsc   mflag,5
        goto    loopw
dunno   goto    wmbt    ;dont know why were here

;))))))))main starts((((((((

See also:

• David A Cary refers to " /techref/microchip/codeflow.htm Up: PIC Microcontroller Program Flow Methods codeflow.htm" +

  .