FeelTech FY6600 60MHz 2-Ch VCO Function Arbitrary Waveform Signal Generator

[DaveR]

Hi fremen, I've given the sweep module a good two hour workout and all appears well to me.  It wasn't a systematic test across all the ranges, more of a "does it do what I need it to do" play around, but it certainly works as expected.  Everything is silky smooth and glitch free, as far as I can tell.  I'll play some more with it over the next couple of days, and no doubt cybermaus will do his technical appraisal when he gets back from buying his loaf of bread.

Thanks again for all the work you've put in to get us this far!

[cybermaus]

I'm sorry.  I've got V 3.0.   Will the blue pills not work with that?

They should, but you'd still need to update your winbond to V3.2

It would actually be interesting to do so, I think no-one actually tried that yet on a corrupted V3.0 because we all assume the corruption is in the STM32, but there is a (very small) possibility the screen corruption is also driven from the Winbond flash and the STM32 is merely badly responding to weird input.

My sample questions are related to the sweep feature.  I thought I'd see if I can contribute something to that.  Is fremen67's  stored waveform swept? I was thinking of writing a program that would  calculate waveforms so that one could load a couple of waveform registers alternately so that one got a smooth sweep by changing the sample rate and waveform register.

Well, current sweep is only to sweep frequency, amplitude, PWM, and those are driven internally by the device STM32, no need to do it from the PC. Also, I think the PC connection is way to slow to do that seamlessly. Best try and get your BluePill based FY6600 running first.

Here is the link to the Winbond flash
Here a couple of samples to BluePill wiring:

[rhb]

Sigh..  More stuff to order from eBay.  So another delay while I wait for a Winbond programmer.

Any comments on these?

https://www.ebay.com/itm/New-USB-Programmer-CH341A-Series-Burner-Chip-24-EEPROM-BIOS-Writer-25-SPI-Flash/253056283240

This seems to be the only thing that will ship from USA.

There are also these, but from China

https://www.ebay.com/itm/ALL-IN-1-Multifunction-USB-to-SPI-I2C-IIC-UART-TTL-ISP-Serial-Adapter-Module-S/202172849567

[DaveR]

The black one works (I've got one), but I haven't seen the other before.  You can also get a clip on connector for the black one to make programming the chip in situ very easy.

[cybermaus]

A 96.9% rating is pretty low though. I am never quite sure how well earned it is, or did the seller just have bad luck with a bunch of nagging buyers.
Then again, $7 will not brake the bank I assume?

[rhb]

@DaveR  can you point me to the clip on connector?

@cybermaus  I hadn't looked at the rating.   I was really just asking about the device.

In many respects, I'm tempted to just punt on this turkey and let someone else play with it.  I've bought a bunch of early 90's vintage HP gear in the last few months and it's a much more satisfying experience.  A *lot* more money than Chinese stuff, but I'm about to turn 65 and decided it was OK to spend some money.  I've been very frugal my whole life, so I can both afford it and feel I deserve it.

[DaveR]

Just search on ebay for "Soic8 Sop8 Test Clip for EEPROM In-circuit Programming" and lots will come up.  Get one with an attached cable and adapters for the CH341A, then it's all just plug in and go.

Regards,
Dave

[SMB784]

@DaveR  can you point me to the clip on connector?

@cybermaus  I hadn't looked at the rating.   I was really just asking about the device.

In many respects, I'm tempted to just punt on this turkey and let someone else play with it.  I've bought a bunch of early 90's vintage HP gear in the last few months and it's a much more satisfying experience.  A *lot* more money than Chinese stuff, but I'm about to turn 65 and decided it was OK to spend some money.  I've been very frugal my whole life, so I can both afford it and feel I deserve it.

I feel your pain, and nobody would blame you for just chalking it up as a loss and moving on.

However, we do appreciate your contributions, and if you ever get that itch to fix something nigh unfixable, we'll be here 

[cybermaus]

In many respects, I'm tempted to just punt on this turkey and let someone else play with it.  I've bought a bunch of early 90's vintage HP gear in the last few months and it's a much more satisfying experience.  A *lot* more money than Chinese stuff, but I'm about to turn 65 and decided it was OK to spend some money.  I've been very frugal my whole life, so I can both afford it and feel I deserve it.

Not quite 65 yet, but old enough to somewhat understand where you are coming from. I have also always been frugal (aka a cheap bastard) and am still amazed at myself how I buy a cheap Chinese AWG when a) I can easily afford the proper stuff and b) I seem to spend relatively high amounts on patching up said AWG with PSU, OpAmps, etc. Truth is, I think I enjoy the challenge and frustration of making things work for pennies on the dollar.

So, my advise, put it to the site when it gets too much, order the $6 programmer just in case, and maybe pick it up again later, or maybe not.

[soundtec]

Someone asked a while back about extra waveforms ,I found some wave drawing software called Easywave  it needed a component called Visa shared components from National instruments  to run , the files it makes are CSV, where I notice the wave files for the Fy6600 are a different format .I wonder is there a way to convert the format, looks a good bit more elaborate than the feeltech software . Im not sure if the FY6600 will talk to this program directly ,but it might be possible to use it to create waveforms all the same .Be interesting to hear from anyone with experience using this or other waveform creation software.

[spec123]

AFAIK the FY6600 PC software accepts CSV files. I normally make my waveforms using a spreadsheet program when I need a lot of detail, like for modulation waveforms.

Some weeks back I tried ArbExpress, a free AWG drawing program from Tek. It seemed to work well but there was a learning curve. Had some fun making silly waveforms to display on a scope.  Recall that you have to adjust some params in the program to fit the format of the FY6600 waveform. It seemed to work. You have to register with Tek to get the free drawing software.

[ledtester]

Wow this is an intense discussion - 51 forum pages in only 8 months!

Looks like a lot of hacking of this device is going on. Would someone be so kind as to provide a short summary of what people are doing?

Thanks!

[DaveR]

AFAIK the FY6600 PC software accepts CSV files.

I'll have to check this out if that's the case.  I've also done waveforms in Excel, but just copied the final values into a text file with a '.fy' extension and uploaded it to the FY6600 with fremen67's control software, which works a treat.  I may be able to save a small step if you can upload a csv directly.

[rhb]

In many respects, I'm tempted to just punt on this turkey and let someone else play with it.  I've bought a bunch of early 90's vintage HP gear in the last few months and it's a much more satisfying experience.  A *lot* more money than Chinese stuff, but I'm about to turn 65 and decided it was OK to spend some money.  I've been very frugal my whole life, so I can both afford it and feel I deserve it.

Not quite 65 yet, but old enough to somewhat understand where you are coming from. I have also always been frugal (aka a cheap bastard) and am still amazed at myself how I buy a cheap Chinese AWG when a) I can easily afford the proper stuff and b) I seem to spend relatively high amounts on patching up said AWG with PSU, OpAmps, etc. Truth is, I think I enjoy the challenge and frustration of making things work for pennies on the dollar.
So, my advise, put it to the site when it gets too much, order the $6 programmer just in case, and maybe pick it up again later, or maybe not.

I'm going to order the needed bits and pieces.  I'd like to have them on hand whether I beat on the Feeltech or not.  i *thought* I had everything already, but had not followed things closely enough to notice the Winbond issue.

My TEC1-12706 Peltier devices came to day so I've started on an experimental build of a small chamber using two in series.

The true definition of wealth is being able to ignore the subject of money.  And the easiest way to achieve that is frugal habits and hard work.

A number of my closest friends have been highly impolite and died without prior permission in the last few years.  It's adjusted my attitude a bit.

[DaveR]

Someone asked a while back about extra waveforms ,I found some wave drawing software called Easywave  it needed a component called Visa shared components from National instruments  to run , the files it makes are CSV, where I notice the wave files for the Fy6600 are a different format .I wonder is there a way to convert the format, looks a good bit more elaborate than the feeltech software . Im not sure if the FY6600 will talk to this program directly ,but it might be possible to use it to create waveforms all the same .Be interesting to hear from anyone with experience using this or other waveform creation software.

I should have read your message first, soundtec - yes, there is a simple method to convert CSV to FY files, just good old copy and paste.  If you've already produced a waveform or two in CSV format, can you post them up so I can see how well they translate?

[SMB784]

Well I have finally finished upgrading the device, I stuck a switch mode power supply into it, along with some new output operational amplifiers, a ferrite for the power rails, and a new txco oscillator.

Other than a few accidental poor connections, everything went swimmingly.

However, I have noticed something rather unpleasant that has caught the attention of other forum members, namely the horrendous jitter when generating non-sinusoidal wave forms at frequencies that are not integer divisors of the 250MHz clock frequency. This jitter really hamstrings the usefulness of this generator.

Has there been a solution identified for this problem?

[cybermaus]

divider of 250MHz, not 50MHz, I am sure you meant to write.
Jitter is 4ns (or indeed 1/250MHz) for vertical edges.

No solution, not even one proposed or speculated, its just part of the fixed PLL. Indeed I would expect the FY6800 to also have this.
Below 1MHz it is not noticeable, above 5MHz it makes your scope screen rather messy, I try to look past it.

[SMB784]

divider of 250MHz, not 50MHz, I am sure you meant to write.
Jitter is 4ns (or indeed 1/250MHz) for vertical edges.

No solution, not even one proposed or speculated, its just part of the fixed PLL. Indeed I would expect the FY6800 to also have this.
Below 1MHz it is not noticeable, above 5MHz it makes your scope screen rather messy, I try to look past it.

Indeed, I meant to write 250 MHz, not 50 MHz.  Of course an integer divisor of 50 will also be an integer divisor of 250 (albeit different integer), but the point is moot.  4ns jitter is pretty ridiculous.  Is it known what aspect of the PLL is causing this jitter?

[soundtec]

Heres three waveforms created on easywave just to test ,the first two have 8192 samples ,the last has 16384.

What Im thinking is that ,maybe by somehow changing or rearranging the memory sample banks the fpga chooses from we could come up with better figures for THD, jitter or aliasing ,which ever you want to call it .  This thread is so long I often end up reading back stuff that Ive forgotten ,but Zov as far as I remember did suggest something along similar lines ,
could for instance starting and finishing a sample not at the zero crossing points but somewhere else in the cycle help , could different frequency samples be used when the frequency isnt set to a divisor or multiple of 250mhz . Its 14 bit at the end of the day I think best case scenario a signal to noise of about 80db is possible ,at an unfavarouble setting of the controls maybe this worsens to about 50-60db.

Just looking across the specs on the 6800 ,they say its now got resolution down to 100uV ,where the minimum step in the 6600 is 1mV, so maybe they have managed to squeeze something more out of it .

[soundtec]

CSV files arent allowed ,so I had to zip them

[cybermaus]

Is it known what aspect of the PLL is causing this jitter?

How do you mean, what aspect?  It's simply the maximum resolution of the clock. Its like asking why a picture with a 1024 resolution has blocks that are 1/1024 width.
Of course, even a picture you can "anti alias", basically faking a fuzzy edge by playing with gray scale, and that is why the sine wave appears better. But hard edges are simply either on one tick of the 250MHz clock, or on the next tick 4ns later. Never in the middle.

To fix this (for hard edges) you'd need to vary the base frequency resolution along with the desired frequency, like with a programmable clock, or with a VCO based clock instead of a PLL based clock. Or heavily overshoot the clock resolution, like sample it on 1GS/s instead of 250MS/s. But that is all done in the FPGA.

[Scyte]

@fremen67:
A few weeks ago you claimed you will put the source code in git-Repo if it is stable. I would say you should do it now: That would speed up the process and would allow other users to help you.
Don't blame of failures: open the source
Scyte

[DaveR]

A bug report for the 0.6 firmware/software package:

Nothing wrong with the sweep module, but I used a different blue pill board for the 0.6 firmware and had to redo the calibration process.  Ch1 Amplitude went ok, but the control software crashed repeatedly while trying to do the Ch1 Offsets (see screen1.jpg).  Restarting the control software brought it back in the configuration in screen2.jpg, and resetting the blue pill brought it back in normal default mode.  I gave up on Ch1 and did Ch2 instead, both amplitude and offsets being set without a problem, then went back to Ch1 offsets, which also completed without further hiccups.  However, pressing either "End Calibration" button then causes another crash as in screen3.jpg (clicking "OK" shuts down the software).

Dave

[DaveR]

Back on waveform files, the FY6600 will accept CSV files, but ONLY if the file contains nothing but the data values up to a maximum of 8192 points.  Clearing out the other cells and info left by wafeform creation software only takes a few seconds in the case of those uploaded by soundtec, so it's just the same as copying the data values into a new text file.  In fact, the software accepts *.txt files as well, so there's no need even ro rename them to *.fy.

I didn't bother uploading the files to the FY6600, soundtec, as the sinc-pulse and triangle waveforms you did are obviously going to display perfectly well from what I saw in the CSV files and the Waveform Window of the control software.  The big square wave file, naturally enough, became a DC waveform as only half of the file could be read in.

[SMB784]

Is it known what aspect of the PLL is causing this jitter?

How do you mean, what aspect?  It's simply the maximum resolution of the clock. Its like asking why a picture with a 1024 resolution has blocks that are 1/1024 width.
Of course, even a picture you can "anti alias", basically faking a fuzzy edge by playing with gray scale, and that is why the sine wave appears better. But hard edges are simply either on one tick of the 250MHz clock, or on the next tick 4ns later. Never in the middle.

To fix this (for hard edges) you'd need to vary the base frequency resolution along with the desired frequency, like with a programmable clock, or with a VCO based clock instead of a PLL based clock. Or heavily overshoot the clock resolution, like sample it on 1GS/s instead of 250MS/s. But that is all done in the FPGA.

That makes sense, excellent explanation thank you.  I'm assuming that a 1GS/s sample rate is out of the question for this particular FPGA part. Forgive my rather basic line of questioning, I'm not an expert in RF engineering.