[time-nuts] algorithms and hardware for comparing clock pulses

Jim Lux jimlux at earthlink.net
Tue Sep 22 00:52:17 UTC 2015


On 9/21/15 12:13 PM, Robert LaJeunesse wrote:
> The Teensy 3.1 (http://www.pjrc.com/store/teensy31.html ~$20) has a Flex Timer Module that appears to allow a single counter to be captured into independent registers from independent inputs. Not sure, but PJRC tends to run the clock fast (96MHz) so relative timing resolution should be much better than 0.1 microseconds.
>

A bit of googling:  FreqMeasure library for the Teensy can time stamp 
zero crossings on pin 3
Apparently, the code is there to use up to 4 pins, but it's not really 
set up for multiple pins.
It uses the hardware to capture, and then an ISR to unload the register 
and buffer them up.

It also works on Arduinos.


https://www.pjrc.com/teensy/td_libs_FreqMeasure.html

the diagram in the K20 manual shows a two stage D flip-flop synchronizer 
driven off the system clock, and then a simple rising/falling edge (or, 
really, a 0->1 or 1->0 transition detector, which then latches the counter.
(Figure 37-175 in the manual)

Is this "time-nuts" precision capable. I've not tried to drive an 
Arduino or teensy with an external clock, which I think might be a 
starting point.


> Bob LaJeunesse
>
>> Sent: Monday, September 21, 2015 at 1:45 PM
>> From: "Can Altineller" <altineller at gmail.com>
>> To: "Discussion of precise time and frequency measurement" <time-nuts at febo.com>
>> Subject: [time-nuts] algorithms and hardware for comparing clock pulses
>>
>>     Dear Time-nuts,
>>
>>   ...
>>     I probably need a hardware to measure the time pulses more precisely.
>>   ...
>>     Are there any solutions to this problem?
>>   ...
>>     Best Regards,
>>     Can Altineller
>> _______________________________________________
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
>




More information about the Time-nuts_lists.febo.com mailing list