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Discussion Groups | Piclist | Re: 12F675 Startup Problems
A discussion group for the PICMicro microcontroller. Also called the Microchip PIC, this list is dedicated to the use and abuse of this fine, simple, microcontroller. Close to topic posts are welcome, ie. general electronics.
Re: 12F675 Startup Problems - starutopy - Dec 15 10:19:43 2007
Hi,
you may try to bypass VDD & VSS by an 100nF capacitor as close as
possible to pin 1 & 8. Then don't connect directly pin 1 to 4, but put
a resistor 100K from pin 1(VDD) to pin 4 (MCLR) and a capacitor 100nF
from pin 4 to pin 8 (VSS).
Best regards
--- In p...@yahoogroups.com, "kg4pid" wrote:
>
> I'm using a serial routine on a 12F675 and started by sending out the
> word "HELLO" over and over. Funny thing is while it's powered on I get
> nothing out, but the instant I remove power it sends out 10 or 11
> characters. The filter cap is powering it for that fraction of a
> second. The circuit is being powered by a 9V battery with a 78L05 to
> regulate it at 5V. My meter reads 4.99v at the pic chip. A logic probe
> connected to the output blinks the whole time it is powered up which
> should mean that its sending something. I had to include this bit of
> code at the very beginning before I got anything at all.
> call 0x3FF ; Retrieve Factory Calibration
> BANKSEL OSCCAL ; BANK1
> movwf OSCCAL
>
> Anyone have any ideas as to what might cause a problem like this?
>
> Thanks, Max
>
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you may try to bypass VDD & VSS by an 100nF capacitor as close as
possible to pin 1 & 8. Then don't connect directly pin 1 to 4, but put
a resistor 100K from pin 1(VDD) to pin 4 (MCLR) and a capacitor 100nF
from pin 4 to pin 8 (VSS).
Best regards
--- In p...@yahoogroups.com, "kg4pid"
>
> I'm using a serial routine on a 12F675 and started by sending out the
> word "HELLO" over and over. Funny thing is while it's powered on I get
> nothing out, but the instant I remove power it sends out 10 or 11
> characters. The filter cap is powering it for that fraction of a
> second. The circuit is being powered by a 9V battery with a 78L05 to
> regulate it at 5V. My meter reads 4.99v at the pic chip. A logic probe
> connected to the output blinks the whole time it is powered up which
> should mean that its sending something. I had to include this bit of
> code at the very beginning before I got anything at all.
> call 0x3FF ; Retrieve Factory Calibration
> BANKSEL OSCCAL ; BANK1
> movwf OSCCAL
>
> Anyone have any ideas as to what might cause a problem like this?
>
> Thanks, Max
>
to unsubscribe, go to http://www.yahoogroups.com and follow the instructions
(You need to be a member of piclist -- send a blank email to piclist-subscribe@yahoogroups.com )