Reset problem

[mischl]

you are really sure that is a reset and not a undebounced input which executes an unexpected part of the code?
how is the BROWN-OUT RESET configure?

good luck

[leonel]

Well, i think i solve my problem.
I have a 78L05 well regulated output with a 10nF ceramic capacitor between +5V and GND, also i also have flyback diodes across inductive loads.
What i did was to increase a little bit my MCLR pin with a diode. (likely the cause was the MCLR pin voltage decrease a little bit), I saw in datasheet and Voltage on MCLR with respect to VSS can go to +13.5V. Also, put a 10nF cap between Vss and GND (near my PIC).

[sayzer]

Here is something to add as a solution for those who still have reset problems.

1: Use 47K trimpot on MCLR pin.
2: Adjust the trimpot untill the resetting stops. Requires hard reset after each change.
3: Remove the trimpot, measure the resistance value, and use a resistor at the same value.
4: Done.

BOD_OFF did not work for me but a trimpot at MCLR pin solved the problem.

GoTo 1

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[Melanie]

I've never designed a circuit that, where MCLR required connecting, nailing it directly to Vdd was a problem (excluding of course ICSP applications). If you have got so much crap coming down your Supply line that trips out your PIC, then it's time you seriously thought about redesigning your Supply circuit. Because if you go and smooth-out MCLR on it's own, the rest of your PIC is still getting a rubbish supply... then that's going to affect Voltage References, Comparators, ADC's, the point at which your I/Os switch etc etc.

[Acetronics2]

Hi, Leonel

One simple solution is to bring the 5 v to the PIC ( only the PIC ...) through a diode ( Low drop Schottky if required ) and havind a BIG capacitor ( say 470 - 1000µF ) connected to the Cathode. This doesn't keep you from having the usual 10µF and .1µF decoupling caps.

This will filter spikes, and allow powering the PIC if supply voltage falls too low.

This also permits to shut down all peripheral components BEFORE the Pic goes to bed ... always having known peripheral states at power off.

Alain

Hi, Mel

When you design an Electronic Ignition or a High Voltage device from a battery , you DO NOT have the choice for a "nice and clean" supply !!! ...

[Melanie]

I disagree Alain

The electronics that you design-in between the PIC and the incomming Power Source, be it vehicular or Battery sourced always ensures the PICs supply is clean. If it's not, then you have a disaster waiting to happen - the TGV will derail, the Président de la République Française will resign, the Government will fall, the Guilotine will be taken out of storage and sharpened - and it will all be your fault.

[Acetronics2]

the Président de la République Française will resign, the Government will fall, .

Do you REALLY think it would be a disaster ???

It's evident you don't live here !!! And you do not know anything about Jacques ( Old friend of mine ... )

Alain

PS: aboard your car, you take a diesel generator for the electronics to work ??? ...