EEVblog Electronics Community Forum
Electronics => Projects, Designs, and Technical Stuff => Topic started by: 0xFFF0 on November 14, 2022, 03:58:58 pm
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Is there a nice simple diy circuit (MCU?) to measure frequencies with an interpolator for finest resolutions?
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Like a vernier?
Use your input pulses to gate a higher frequency (precision) oscillator.
www.instructables.com/High-Resolution-Frequency-Counter/ (http://www.instructables.com/High-Resolution-Frequency-Counter/)
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For hobby applications the simplest is to use a TDC7201 and a microcontroller. With this a resolution of RMS 60ps is possible. Search this forum and visit the (German) site : http://www.mino-elektronik.de/ (http://www.mino-elektronik.de/) for schematics.
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The chip is quite interesting but hard to source.
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what frequncies Hz, MHz, GHz?? Idle curiosity Hz?
You might want to consider a low jitter clock mutiplier (digital PLL).
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What is the application where you want to use the frequency meter?
And what minimum resolution do you need?
Another solution to the vernier is to use a CTMU module of a PIC microcontroller. It is a module that charges a capacitor with a constant current for very small time intervals. By measuring the capacitor voltage with the ADC, the size of the time interval can be known. It can measure intervals with a resolution of 200ps.
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Isn't that all done by the 7200 chip?
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The chip is quite interesting but hard to source.
https://www.mouser.de/c/?series=TDC7201 (https://www.mouser.de/c/?series=TDC7201) 1925 in stock 4,17 € each.
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Without TDC: https://www.eevblog.com/forum/projects/8-11-digits-reciprocal-frequency-counter-0-1-hz-150-mhz/msg3386880/#msg3386880 (https://www.eevblog.com/forum/projects/8-11-digits-reciprocal-frequency-counter-0-1-hz-150-mhz/msg3386880/#msg3386880)
(PCB available, G431: https://lcsc.com/product-detail/Microcontroller-Units-MCUs-MPUs-SOCs_STMicroelectronics-STM32G431KBT6_C529357.html (https://lcsc.com/product-detail/Microcontroller-Units-MCUs-MPUs-SOCs_STMicroelectronics-STM32G431KBT6_C529357.html))
or reduced functions a little bit cheaper by using RP2040 picoboard (coming at end of 2022-11).
Or you use AS6501 in LQFP48: https://www.mouser.de/ProductDetail/ScioSense/AS6501-FLQM?qs=%252BEew9%252B0nqrAbCpBiX0DUew%3D%3D (https://www.mouser.de/ProductDetail/ScioSense/AS6501-FLQM?qs=%252BEew9%252B0nqrAbCpBiX0DUew%3D%3D)
Attention: TDCs need some extra logic to synchronize start-stop-signals.
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Pretty impressive project. But that's beyond my capabilities at the moment.
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You'd better tell us what do you want.
what frequncies Hz, MHz, GHz?? Idle curiosity Hz?
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You can get the idea here:
https://www.eevblog.com/forum/projects/diy-interpolating-frequency-counter-fc-510/ (https://www.eevblog.com/forum/projects/diy-interpolating-frequency-counter-fc-510/)