PIC based frequency counter

[ehnonymouse]

Does anyone have any information about the PLJ-8LED frequency counters being sold on eBay? They use a PIC16F648A. Are they part of an open source project you recognise and if so do you have any links to code and schematics please? I want to modify one to have three switchable I.F.s but need to understand how it is currently working.

[towlerg]

Don't know about that device but the microchip app note AN592 is the basis.

Something perhaps similar http://homepage.eircom.net/~ei9gq/counter.html

[PICker]

Other similar projects:
http://www.qsl.net/dl4yhf/freq_counter/freq_counter.html
http://www.best-microcontroller-projects.com/pic-frequency-counter.html
http://www.circuitvalley.com/2011/07/60-mhz-frequency-meter-counter.html
http://www.micro-examples.com/public/microex-navig/doc/110-p16f84-freqmeter.html
http://microcontrollerslab.com/digital-frequency-meter-with-lcd-display/
https://sites.google.com/site/vk3bhr/home/fm2
http://www.apogeekits.com/counter_article.htm

[ehnonymouse]

Thanks guys, I have seen a lot of those and some others too, but nothing seems to be up there with this eight digit one.

[PICker]

Hi @ehnonymouse,
the only datasheet I've found for the PLJ-8LED is in chinese language!
http://www.sv1bds.gr/files/PLJ_5110C.pdf
Anyway, several schemes and formulas are clear.

[titi]

Hi ehnonymouse,

in attachment the documentation in chinese for PLJ-8LED-C.
At the end of the document you can found some links.
May be it is possible to use google translate in you native language ?

A Video and PDF for PLJ-6LED-A : https://www.youtube.com/watch?v=1_neC5Z_wEg

I just add an other documentation in French.

And this is a duch site : http://www.rudiswiki.de/wiki9/FrequenzZaehlerLED

And some other documentations : http://pan.baidu.com/share/home?uk=369802936#category/type=0

Best regards.

[Vineyards]

I think, now that you are looking to get such an extended resolution and accuracy, you need two things:
1- A reliable, low ppm crystal with a frequency calculated to match your desired specs.
2- Assembly coding which takes into account the time it takes for every little command to be processed by the mcu.
We could add to that the need for premium components and a careful circuit design taking into account interferences etc.

Zuisti is the master of this art as far as I can remember. If he is around he can give you a few tips. I built a frequency counter some 5-7 years ago but I was not targeting that much precision.

[dR-mR]

This one is from silicon chip magazine
2.5Ghz 12 digit resolution
http://www.radioradar.net/en/measurements_technics/2_5_ghz_12_digit_frequency_counter_with_add_on_gps_accuracy.html

[PICker]

I do not know if this is out of topic, but, referring to the Vineyards post, several links and/or appnotes may help in the development of an accurate frequency counter:
http://www.keysight.com/upload/cmc_upload/All/measurement_error.htm?&cc=IT&lc=ita
http://leapsecond.com/hpan/an200-4.pdf
http://www.ni.com/white-paper/3619/en/
http://www.techni-tool.com/site/ARTICLE_LIBRARY/Agilent%20-%2010%20Hints%20for%20Getting%20the%20Most%20from%20Your%20Frequency%20Counter.pdf
http://www.sitime.com/support2/documents/AN10033-Frequency-Measurement-Guidelines-for-Oscillators.pdf
http://cp.literature.agilent.com/litweb/pdf/5967-6038E.pdf
http://cp.literature.agilent.com/litweb/pdf/5989-1592EN.pdf

[ehnonymouse]

titi - PLJ-8LED-C.pdf looks very useful, and dR-mR, thank you for http://www.radioradar.net/en/measurements_technics/2_5_ghz_12_digit_frequency_counter_with_add_on_gps_accuracy.html - it looks really useful.
Thank you to everyone who has replied.

The forum links in PLJ-8LED-C.pdf look really interesting, but I don't know Chinese. I have a friend who does, and he's back from Chinese New year holiday on Monday, so I may get some progress there. Specifically I'd like source code that I can modify.
 
I'm sorry there has been such a long delay in replying but a friend was diagnosed with terminal Cancer, so spare time has been spent supporting him. He died and I'm trying to sort out his estate. Life has been pretty much on hold for a year and still isn't back to normal. Profound apologies.

[titi]

Hi ehnonymouse,

I found some new information about PLJ-8LED-C.

Here is an English documentation and Schematics of the Counter.
Best regards.

[sadman]

Hi ehnonymouse,

I found some new information about PLJ-8LED-C.

Here is an English documentation and Schematics of the Counter.
Best regards.

where to find hex or programing files

[Xaby]

You won't fiind hex for it.

[ehnonymouse]

I've been having problems with this. I have worked out the schematic, but it seems the timer used in the PIC needs to somehow synchronise with the PIC clock. The result is that if the PIC is running with a 13MHz clock (as supplied from China), putting a 10MHz signal in results in a count of 3MHz. The original as supplied counter will count to 1Hz resolution a 10MHz signal with a 1s gate time.

Any ideas how they manage it?

[Old_but_Alive]

The manual for the PLJ-5110C looks a nice item.
Unfortunately, there are no google hits.

anyone know where it is available?

[titi]

Hi,

This Chinese document give schematics and other explanations, may be it can help you.

http://www.sv1bds.gr/files/PLJ_5110C.pdf

Best regards.

[Old_but_Alive]

that was the document i looked at, so no bloody help at all

[ehnonymouse]

Hi,

This Chinese document give schematics and other explanations, may be it can help you.

http://www.sv1bds.gr/files/PLJ_5110C.pdf

Best regards.

Thanks. I worked out the schematic and how they do the gating by hardware. I got a Chinese friend to help me log onto the forum where they discuss it, but the download is only allowed for certain people. I was hoping to read the assembler and see how they manage it. This could be a very useful counter if only I could change the code to allow multiple offsets.

[Pavos]

On the links below you can find documentation and software for very useful counter.

http://www.vhfcomm.co.uk/Counter.pdf
http://lea.hamradio.si/~s53mv/counter/history.html

[titi]

Hi ehnonymouse,
About the version PLJ-6LED-R3 based on PIC16F648A (PIC16F628A like, with 4k of program and a bit more RAM).
I bought 2 items of these version.
I searched for the source to modify this module to read frequency below 100kHz (that is the minimum for this version).
I found nothing !
So I write myself a program for this module using MikroBasic and Inline Assembly.
The program can read frequency with only one gate of 1s, every frequency from low frequency until above 65Mhz so the precision is the precision of xtal of 13MHz TCXO of 2.5ppm.

Display:
   Like the display has only 6 digits, it display frequency like this :
  1234 Hz
  123456 Hz
  1.23456 MHz
  12.3456 MHz
To keep all digits it could be possible to scroll the display, but not implemented in my current version.

Keys:
  The upper key is for change the brightness from 0 to 7
  The lower key save in EEPROM the value selected for the brightness

IF Offset:
  I have no use of IF Offset, so I don't implement It.
  If you want to use IF Offset like the program give you the frequency in a Long word of 32 bit, you just have to subtract by example 455000 (or ADD) before Display the result.

Be careful with other version of this module, because in version R3 there are some changes: the DIO and CLK of TM1637 is not on the same PIN of PIC, Keys are directly connected on the PIC and not on TM1637.
I show differences on the schematic.
The program used 1252 bytes of program and 45 bytes of RAM so this program can be adapt on other version based on PIC16F628A.

Don't use this program, if the version of your module is not R3, but you can use it to understand how it is working and you can adapt it for your version.

Best regards.

[sadman]

The zip file is giving error. any idea why ?

the shifting of forum to new host lots of attachment are corrupted may be original up loader may share it again zip file is opening fine only schematic is corrupted.

[Checksum8]

See if this will open

[titi]

Hi,

I just re-uploading the zip file and the Schematic.

Best regards.