Sorry for the follow-up

Does it sound like an obvious case of floating-pin-syndrome? I haven't yet
made sure all pins are going somewhere (testing incrementally is easier this
way), but is it still strange only pin RA4 has this problem?


In a faraway galaxy, Dennis Noordsij wrote on Sunday 14 October 2001 00:50 :
> Heips,
>
> I am using a PIC16F877 and am stuck with a strange problem, which I hope is
> due to a mistake on my part rather than a broken PIC.
>
> Summary:
>
>         bsf   STATUS, RP0       ; Use register bank number 1
>
>         movlw b'10000110'       ; Set port A as digital I/O
>         movwf ADCON1            ;  instead of ADC
>
>         movlw b'00000000'       ; All pins set to output
>         movwf TRISA             ;  on port A
>
>         movlw   H'FF'           ; Assert all pins
>         movwf PORTA             ; on port A
>
> I upload it to the chip using a bootloader and serial connection, and reset
> the circuit.
>
> All pins on port A now measure 5.00 volts between them and GND, EXCEPT for
> pin 4 (RA4/T0CKL), which measures something between 0.8 and 3.3 volts.
>
> Usually I would blame this on a connection problem somewhere, but now I am
> using a breadboard and the pin in question is not connected to anything
> (neither are the other port A pins).
>
> Maybe it has something to do with the timer associated with that pin? I
> have tried some different configurations, and each one got a different
> voltage, but never the normal +5V.
>
> What do I need to do (starting with the default startup configuration) in
> this case, using the PIC16F877 @ 4 MHz with a crystal oscillator using the
> following config word:
> _CP_OFF
> _WDT_OFF
> _BODEN_ON
> _PWRTE_ON
> _XT_OSC
> _WRT_ENABLE_ON
> _LVP_OFF
> _DEBUG_OFF
> _CPD_OFF
>
> Hope the chip is ok :-)
> Thanks for any pointers,
> Kinds regards
> Dennis Noordsij

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