Bruce Griffiths wrote:
Bruce Griffiths wrote:
Magnus Danielson wrote:
Fellow time-nuts,
To support the kind of burst measurements I am playing around with
it would be good to be able to generate bursts of transitions rather
than even clocks. Depending on the counter it may be simple (say
using a HP5372A) or a little more difficult (DTS 2070C).
Creating a burst of 10 kHz transitions for 10 or 100 ms should be
possible to do in the PIC code with some hacking.
Similarly creating a burst of 5 or 10 MHz clocks for 1 ms should not
be too hard by sniffing the clock after the input shaper and the
enable pulse from the PIC.
I thought I would bounce this and see if people have any ideas other
than mine... anyone else interest...
Cheers,
Magnus
Since an external gate is required to implement the 5/10MHz clock
burst it would be simpler to have a selectable pulse width for say
the PPS output and use this to gate either the 5MHz/10MHz or 10kHz as
required.
Bruce
A simple external circuit accomplish this would use an octal gated D
flipflop (74AC377) plus a quad NOR gate (74AC02).
For a 100ms burst every second connect 10PPS to the enable input of
the 377, clock the 377 with the 10MHz signal, wire the 377 as a 2 bit
gated shift register with the shift register input connected to PPS
and use the output of the second stage of the shift register to gate
the 10MHz output using the NOR gate (remember to invert the shift
register output first).
Bruce
Correction: make that a 3 input NOR and use the output of both the first
and second stages of the 2 bit shift register to gate the clock.
BURST = SR(0)*/SR(1)*/CLK
If one wants a burst of 10kHz pulses, invert the 10KHz signal and use
this to clock the 2 bit gated shift register
Bruce
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