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BROWNOUT on dsPIC 33J128GP802?

 
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leporid



Joined: 04 May 2010
Posts: 6

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BROWNOUT on dsPIC 33J128GP802?
PostPosted: Thu May 27, 2010 11:47 am     Reply with quote
I am getting a BROWNOUT reset code (=1) from reset_cause()
on a dsPIC 33J128GP802? after a few (varies) seconds of
normal operation. I can't find any info on BROWNOUT for
this chip, and BROWNOUT_ENABLE(FALSE) isn't accepted
by the compiler. The reset keeps repeating once it starts.

- Is there a BROWNOUT feature on this chip? If so,
how can I disable it?

- Is there any way this reset could be simulated by
some other problem?

The benefit of your experience would be much appreciated.
PCM programmer



Joined: 06 Sep 2003
Posts: 21708

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PostPosted: Thu May 27, 2010 12:14 pm     Reply with quote
I looked at the PIC data sheet. It doesn't appear that Brownout Reset
can be disabled on this chip. The Brownout feature is part of the
internal voltage regulator on the chip. The threshold voltage is 2.5 volts.

What if you actually are getting a Brownout reset ?

Read this section. Make sure you have this external capacitor
and that it's the correct type:
Quote:

2.3 Capacitor on Internal Voltage Regulator (VCAP/VDDCORE)


Also read this section (it's on the same page). Make sure you have
all the required bypass caps and bulk capacitors.
Quote:

2.2.1 TANK CAPACITORS


I think if you left off all these caps you might be getting a Brownout.

Also make sure your main power supply for the board is putting out the
correct voltage and can supply the required amount of current.
leporid



Joined: 04 May 2010
Posts: 6

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Brownout and VCAP/VDDCORE
PostPosted: Thu May 27, 2010 3:18 pm     Reply with quote
Great lead, and prompt response, thanks.

I looked up your references
and then learned that the board has a .01uF
cape on the VCAP/VDDCORE pin, not the 1-10
uF specified. I didn't design it, but I should have
checked it anyway. I was sure it was a coding
error that just looked like a brownout!

I think this problem will go away soon.

Smile
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