You can use a retriggable one-shot trigger to do the job. Set the time
constant of the one-shot to something like 1.5us. Use the 1MHz clock to trig
this one-shot. When a clock pulse is missing it will fail to trig the
one-shot within 1.5us then the one-shot will give you a pulse output.

Hope this helps.

Raymond

-----Original Message-----
From: pic microcontroller discussion list
[mailto:PICLIST@MITVMA.MIT.EDU]On Behalf Of lu01ts@GMX.NET
Sent: January 20, 2002 5:00 PM
To: PICLIST@MITVMA.MIT.EDU
Subject: [EE]: Missing Pulse Detector


Hello Picsters,

I want to detect one or more missing pulses on a clock - line (1 MHz)!

My idea was to sample the clock - line using 2 Mhz and let a counter
be reset if both lines are high (puls detected). If the counter
reaches a specific value, then there must have been a pulse missing.

I'm sure you guys have several better ideas an I would be glad to
learn your tricks :-)

Greets,
       Michael

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