[time-nuts] Frequency counter questions

Bob kb8tq kb8tq at n1k.org
Wed Apr 26 06:59:55 EDT 2017


Hi

> On Apr 26, 2017, at 12:29 AM, Jerry Hancock <jerry at hanler.com> wrote:
> 
> Do typical  frequency counters start their gate in phase with the incoming signal?  I guess the 
> answer would be, "It depends."  I was just thinking about how I would program the STM32F7 
> counter I am designing.

Since they don’t start (or stop) the gate in any specific relation to the input signal, the trick is to
make sure you don’t get an extra count when the gate opens or closes. This is right back to the
edge triggered vs level triggered issue. It also gets indirectly into the rechecking process in the
MCU. Some of the “edge trigger” stuff is done in odd ways ….(= got two of the same after rechecking
into a shift register …).

Bob


> 
> btw, Gilbert, a local time-nut, sold me a 5335 today so I will be able to buiild one great one 
> out of the two I will have.
> 
> Jerry
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