As a followup.

This ridiculousness is due to the brownout reset.  If enabled, and set 
to 4.6V, it will never run on a 5V supply.  If disabled, or enabled and 
set to 4.3V or lower, it runs fine.

As far as I can tell this is another undocumented PIC hardware bug that 
has caused me to lose half a day and major frustration with a project on 
an aggressive timetable.

I welcome any explanation why a PIC running at +5V would ever be locked 
up due to brownout.  I can't fathom.

This experimentation was done using the config bits setting in the 
latest MPLAB.  The CCS compiler has nothing to do with it.

Argh.  Another reason I use AVRs for all new designs.

J




Jesse Lackey wrote:
> ....just a shout-out to see if I'm doing something dumb.
> 
> I have a design with the PIC18F6410, and I can get it to program, but 
> not start running.  At all, ever.  Not with xtal, or internal RC.
> 
> I haven't used the 6410 before, and it could be a problem with the CCS 
> compiler (my copy is 2 years old - the chip is supported, but that 
> doesn't mean it works).  CCS seems to be setting the config bits 
> properly.  I can check/set them in MPLAB.  No help.
> 
> The footprint and specs (as far as voltages / xtal go, anyway) look to 
> be the same as the 6520, which I have used in a half dozen designs.
> 
> I'm using MPLAB 8.3.  I have MCLR/ pulled up to +5V with a 10K.  The 
> xtal is a 10Mhz of the same type I've used in other designs.  At 
> power-on I can see the MCLR/ line rise as normal.  I have decoupling 
> caps on each pin that gets +5V.  The +5V line has a bulk 220uF cap, and 
> comes from a DC bench supply.
> 
> I can program it all I want, never starts running, no current draw.
> 
> I'm trying to use the 6410 to save $3 per chip for the production run, 
> but am about to drop $70 to digikey overnight more 6520s to save this 
> underfunded, poorly scheduled project.
> 
> Any advice appreciated.  I'm kind of losing my mind right now.
> 
> Thanks.
> J
> 
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