extend the range of frequency counter - Page 1
Forum section: electronics / projects

author: yalect
author_rank: Regular Contributor
timestamp: January 23, 2016, 07:30:41 pm
content: Hello,I would like to ask you about extending the range of freqency counter I have project based on PIC16f84 I want to extend it to measure up to 1Ghz I found some circuit but theydon't display good number format, I want simpe one withPIC16F84Thank you

author: Fraser
author_rank: Super Contributor
timestamp: January 23, 2016, 07:34:42 pm
content: Select a prescaler IC for your desired frequency range. Add some amplification before the prescaler and you are in business. This is how commercial frequency counters are made. There are many prescalerler IC available and they need a mini,um of external components.Fraser

author: Kleinstein
author_rank: Super Contributor
timestamp: January 23, 2016, 09:06:18 pm
content: There are several prescalers / dividers available. For the 1 GHz range this are mainly ECL type chips. WIth some of them sensitivity is allready resonably good (e.g. 100 mV level), others may need an input amplifier. Usually also some input terminaton and protection is needed.But keep im mind - with a classical counter (most plans based of pic16... found in the web), the resolution is reduced with a prescaler. So no more 1 Hz resolution at 1 s gate time.

author: joeqsmith
author_rank: Super Contributor
timestamp: January 23, 2016, 11:04:34 pm
content: Can you post some details about the counter you have?

author: andre_teprom
author_rank: Regular Contributor
timestamp: January 24, 2016, 12:47:03 am
content: Quote from: Kleinstein on January 23, 2016, 09:06:18 pmDepending on the application requirements, the decrease in resolution due to the pre-scaling might be acceptable, so being this case I would dare to say that the circuit should be called as a frequency meter rather than a counter. Anyway, seems like lacking additional details concerning to the design specifications.

author: yalect
author_rank: Regular Contributor
timestamp: January 24, 2016, 04:47:41 pm
content: Hello,thank you for your repliesI found some circuits in the web for frequency counter adding prescaler to extend the range of the measure but displaying format of the number is not good I think that the best format to display the Hz range in Ghz is "1000.000.000"Hz but I didn't find the source code for such format working withPIC16F84Have you an Idea simple circuit or project?

author: Kalvin
author_rank: Super Contributor
timestamp: January 24, 2016, 05:07:58 pm
content: Well, if you cannot find a project for the PIC16F84 you might want to take a look at some other project with suitable specifications and source code available. The processors are very cheap.

author: andre_teprom
author_rank: Regular Contributor
timestamp: January 24, 2016, 05:56:40 pm
content: Working with such high frequency, a lossless counting resolution could be obtained directly by a core having a 32-bit ALU, but I'm not sure if you can find some part able to handle input at that rate, therefore the natural recommendation would be perform it based on a CPLD approach, but I admit it is a bit off-topic in face of your original demand.

author: zapta
author_rank: Super Contributor
timestamp: January 24, 2016, 06:22:54 pm
content: Quote from: yalect on January 24, 2016, 04:47:41 pmAdding a scalar will not change the number of significant digits on your display. If your scaler is decimal (e.g. divides by 10 or 100 or 1000...) than all you need to do is display more zero on the right or shift the decimal point such that it display KHZ or MHZ (e.g. 1000000. KHz for 1GHz input). May be easier than shifting the display left by three places, adding zeros on the right.BTW, dannyf has here the schematic of a minimal PIC based frequency counter. By minimal I mean really minimal, not even LED current limit resistors.https://www.eevblog.com/forum/microcontrollers/minimalist-frequency-meter/