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RandoSY / perfect-pic-plaground

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TLC5940: PIC resets after few seconds of operation #1

Closed GoogleCodeExporter closed 9 years ago

GoogleCodeExporter commented 9 years ago 
PIC runs fine for a few seconds but suddenly resets causing jittery colors. 

The PIC has been verified as resetting by monitoring RB4 with the logic 
analyzer. RB4 is toggled directly after the TRIS and PORT setting in main to 
indicate a start up has taken place.

Possible Causes Checked:
MCLR pulled high: no effect
1uF Cap on VDD to VSS: no effect

Original issue reported on code.google.com by m.kapusc...@gmail.com on 4 Jan 2012 at 2:24

Attachments:

GoogleCodeExporter commented 9 years ago 
The problem appears to be related to interference being introduced somewhere. 
When the circuit is powered from my ATX switched mode, and a load is suddenly 
applied to the 120vac power strip (such as the stoplight) the circuit 
occasionally turns off. My guess would be this is HF interference making its 
way through the PSU as I have applied > 100uF caps to the power rails with no 
success.

Original comment by m.kapusc...@gmail.com on 5 Jan 2012 at 8:27

GoogleCodeExporter commented 9 years ago 
I have not been able to replicate the problem; my circuit has been running 
without problems for at least 10 minutes. I don't have it on a power strip with 
other devices though. Try putting capacitors right next to every power pin of 
the PIC and the TLC5940.

If that still does not work, try putting a number of different sized capacitors 
(1uF, 10uF, 100uF) on the power rails, since at higher frequencies, capacitors 
turn into inductors, and the larger the capacitor, the sooner this happens.

Original comment by vogonpoe...@gmail.com on 6 Jan 2012 at 10:32

GoogleCodeExporter commented 9 years ago 
I threw a 2000uF cap on the power rails, and a 1uF cap across vdd/vss for both 
the pic and the tlc. However, I did find out that if I disconnected my laptop 
and the pickit from the circuit, it was fine. I am assuming that interference 
was being introduced through the pickit somehow which is weird because my 
laptop was running on battery at the time.

Original comment by m.kapusc...@gmail.com on 7 Jan 2012 at 8:41