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'POR bit?'
1998\07\30@023351 by Dr. Imre Bartfai

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Hi all,

I'm using a PIC 16C710/711. I implement the idea that the circuit does
some data collection, and after a MCLR reset the stored result will be
sent out. To distinguish between MCLR reset and POR one I was glad to see
the POR bit in the 8E register. I tried to use it but it does not seem to
work (I read it, if it is 0, I assume it is a POR reset AND I set it to 1.
This 1 should be reset only during POR. However, it is always re-set to
zero.)
Now I set a particular register to 5Ah as it is odd enough not to be set
accidentally, and I check that register whether it is 5Ah (-> MCLR) or not
(POR). However, I see, it is a Q&D solution.

Have you any experience with that POR bit? Do I something wrong?

Thanks in advance
Imre

1998\07\30@111908 by Peter L. Peres

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POR detects MCLR which is always asserted at power-up. If you assert MCLR,
POR will be cleared. More exactly, there is no such thing as a power on
without a MCLR assertion. It will not be cleared if the reset occurs due
to a watchdog timeout f. example.

Peter

1998\07\31@032141 by Dr. Imre Bartfai

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Hi all,

excuse you all, it was the manual wrong. On a particular side states, that
PCON register should have the address 8Eh generally. It is not true. On
the particular memory map one can see, that PCON is 8Eh only for
16C72/73/74. However, for the 16C710/711 (in my case) the address is 87h.
It is silly from Microchip as before the particular registers have all
their constant address.

POR does not detect MCLR; it detects really Power-on-Reset. So, after I
corrected my program, I can distinguish between Power-on and other type of
resets (e. g. MCLR). It is very fine as I collect some data beginning from
power-up, and I will show this data if the user ties MCLR to ground.
The following code snippet can show it:

       ...
       JNB     POR,:POR        ; if not set, then POR
       ...                     ; process collected data here
       BTFSS   POR             ; only for cleanlyness
:POR    BSF     POR             ; now WE set POR to mark it for the future
       ...

Remember, that POR EQU PCON.1   and  it resides in the bank#1, so RP0 is
to be set.

Thanks once again who wanted to help me.

Imre



On Thu, 30 Jul 1998, Peter L. Peres wrote:

> POR detects MCLR which is always asserted at power-up. If you assert MCLR,
> POR will be cleared. More exactly, there is no such thing as a power on
> without a MCLR assertion. It will not be cleared if the reset occurs due
> to a watchdog timeout f. example.
>
> Peter
>
>

1998\07\31@072655 by Peter L. Peres

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Sorry, I oopsed. I had assumed that you were talking about TO and PD, and
i was really tired. I'll censor my postings much better from now on ;)

Peter


'POR bit?'
1998\08\02@060532 by White Horse Design
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At 08:23 30/07/98 +0200, you wrote:
>
>I'm using a PIC 16C710/711. I implement the idea that the circuit does
>some data collection, and after a MCLR reset the stored result will be
>sent out. To distinguish between MCLR reset and POR one I was glad to see
>the POR bit in the 8E register. I tried to use it but it does not seem to
>work (I read it, if it is 0, I assume it is a POR reset AND I set it to 1.
>This 1 should be reset only during POR. However, it is always re-set to
>zero.)

Are you using an emulator?

The ICEPIC (which uses the Microchip bond out cpu's) does not emulate the
POR bit.

Regards

Adrian

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