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PaulStoffregen / FreqCount

Measures the frequency of a signal by counting the number of pulses during a fixed time.
http://www.pjrc.com/teensy/td_libs_FreqCount.html
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Freq count t4 branch #12

Closed mjs513 closed 5 years ago

mjs513 commented 5 years ago

Evening Paul Sorry for all the confusion with the last PR. We were still making improvements to the FreqCount lib. @manitou changed the Qtimer cascade so only pin 9 is used: https://forum.pjrc.com/threads/54711-Teensy-4-0-First-Beta-Test?p=211019&viewfull=1#post211019. In lieu a spending a couple of hundred of dollars I picked up a Adafruit Si5351A Clock Generator Breakout Board(8KHz to 160MHz). Maybe not perfect but did the job. Note there are a couple of pages of discussion on pages 154-156 :)

Results of that testing: https://forum.pjrc.com/threads/54711-Teensy-4-0-First-Beta-Test?p=211087&viewfull=1#post211087. Off a few hundred counts at the higher frequencies but not bad comparison probably within the error of the clock generator and crystal on the Teensy. We figure 68Mhz is the max for the T4.

If you ever have a couple of minutes maybe you give it a go with a real frequency generator.

PaulStoffregen commented 5 years ago

is this ready to merge?

mjs513 commented 5 years ago

Morning Paul Yes sir it is. @manitou and I just posted some additional tests results.