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Undesirable 68334 PortE power up glitch on pin PE6.

2003-01-16 by Daniel Cumming

Hello everyone,

We are using PortE to control some digital outputs in our device.  We have discovered a glitch on one of our digital outputs (the one controlled by PE6).  The following facts should help clarify:

1.  There is a ~250us space on PE6 which has weak internal pull-up on it (according to the manual).  The falling edge corresponds to the low to high transition of the reset line after power up.  
2.  The glitch happens before any code gets executed.
3.  The glitch does not appear on any of the lines PE1-3, also used for digital outputs.
4.  The glitch appears regardless of whether or not D8 is tied to ground with 10K to enable reset mode select to PortE.
5.  The PE6 pin directly feeds an AC logic gate.


thanks,

Daniel A. Cumming, B. Eng.
7300 Series Product Prime
Power Measurement
2195 Keating Cross Road
Saanichton, B.C., Canada
V8M 2A5
E-Mail: <mailto:daniel.cumming@...>
Website: <http://www.pwrm.com/>

ION(r)  smart energy everywhere(tm)

RE: [68300] Undesirable 68334 PortE power up glitch on pin PE6.

2003-01-16 by Melear Charles-rdph40

Daniel,
 
How long is this glitch?  Can you give me some type of rough drawing showing the glitch with respect to the release of reset?
 
Thanks,
 
Charlie

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-----Original Message-----
From: Daniel Cumming [mailto:Daniel.Cumming@...]
Sent: Thursday, January 16, 2003 4:03 PM
To: 68300@yahoogroups.com
Subject: [68300] Undesirable 68334 PortE power up glitch on pin PE6.

Hello everyone,

We are using PortE to control some digital outputs in our device.  We have discovered a glitch on one of our digital outputs (the one controlled by PE6).  The following facts should help clarify:

1.  There is a ~250us space on PE6 which has weak internal pull-up on it (according to the manual).  The falling edge corresponds to the low to high transition of the reset line after power up.  
2.  The glitch happens before any code gets executed.
3.  The glitch does not appear on any of the lines PE1-3, also used for digital outputs.
4.  The glitch appears regardless of whether or not D8 is tied to ground with 10K to enable reset mode select to PortE.
5.  The PE6 pin directly feeds an AC logic gate.

thanks,

Daniel A. Cumming, B. Eng.
7300 Series Product Prime
Power Measurement
2195 Keating Cross Road
Saanichton, B.C., Canada
V8M 2A5
E-Mail: <mailto:daniel.cumming@...>
Website: < http://www.pwrm.com/ <http://www.pwrm.com/> >

ION(r)  smart energy everywhere(tm)

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