Author Topic: VGA, RS232@1Mbps on optical fiber  (Read 5593 times)

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Offline DiTBhoTopic starter

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VGA, RS232@1Mbps on optical fiber
« on: January 23, 2024, 10:02:34 am »
So, I feel the need to move data in a very noisy environment due to high electromagnetic activity.

Fiber optics cables are immune, so that's fine, but since it's a personal experiment, I'm really on a budget(1).

I need to export both VGA@1024x768, and uart@1Mbps, I see there are some products on eBay... anyway...would you trust a metal box that says "OptEcal Fiber" on the top?  :-//

Now I don't want to judge the book by its cover, but if you don't even realize that the serigraphs of the product you sell are wrong...  or you just don't care, and you don't correct them, well... there are probably also hw/sw/fw patches that you don't know/don't care about.

Which usually means troubles for the final user ...

-

Has anyone played with that stuff before, any products with good feedback to suggest?

(1) Say, less than 200 euro for both the transmitter and the receiver, if this makes sense.
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Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #1 on: January 23, 2024, 10:04:31 am »
at most I can build the { RX, TX } modules myself, but I have no experience with the optoelectronic parts.
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Offline berke

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #2 on: January 23, 2024, 10:20:54 am »
Convert your VGA and UART to Ethernet with a USB capture card and USB to serial adapter using an RPi or something similar, then use an Ethernet media converter to fiber and back.  If you really need VGA and serial output, add an HDMI-to-VGA dongle and another USB-to-serial adapter at the other end.  Parts list:

- Two RPis
- VGA-to-USB capture dongle
- Two serial-to-USB converters
- HDMI-to-VGA dongle

Software:
- For video, probably something based on GStreamer
- For UART, socat might do the trick if you don't need to transmit breaks
 

Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #3 on: January 23, 2024, 10:34:37 am »
Universal solution to everything, world peace, food crisis, cancer etc: use an rpi!!!! (sarc)
Sorry, no!
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Offline pcprogrammer

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #4 on: January 23, 2024, 10:35:13 am »
No experience with but a search on KVM over fiber yields some interesting results.

https://www.rextron.com/Fiber-Extenders.html
https://www.blackbox.co.uk/gb-gb/1439/VGA-KVM-Extenders
https://video.matrox.com/en/products/kvm-extenders

Maybe something can be found in your price range and requirements.

Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #5 on: January 23, 2024, 10:37:55 am »
to avoid any further misunderstandings:
  • must be a pure hw embedded solution
  • without involving a GNU/Linux SBC systems or other loopholes of that type
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Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #6 on: January 23, 2024, 10:42:22 am »
No experience with but a search on KVM over fiber yields some interesting results.

Fiber-Extenders
VGA-KVM-Extenders
kvm-extenders

Thanks for the links! Interesting!
That's why I opened this topic: looking for real experiences! Or any suggestions for self-building the modules!
(which I remember, must also carry uart@1Mbps)
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Offline Berni

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #7 on: January 23, 2024, 10:58:31 am »
Universal solution to everything, world peace, food crisis, cancer etc: use an rpi!!!! (sarc)
Sorry, no!

Well you can still use a x86 PC with a capture card. The beauty of that solution is that it uses all off the shelf consumer things including off the shelf fiberoptic network equipment. So this means devices with a large economy of scale behind them, so cheep to buy.

to avoid any further misunderstandings:
  • must be a pure hw embedded solution
  • without involving a GNU/Linux SBC systems or other loopholes of that type

What you need is a pretty niche specialized thing, so you will need to pay up the big bucks, or make do with the chinese solutions.

The Chinese tend to be the first place i go to when i need something done cheap. Sure they might not be the highest quality solutions, but i am not usually building a launch control system for a ICBM. I just make sure to test the chinese crap really well to make sure it works for my use case. If it works great, i saved a lot of money, while if it doesn't work just toss it in the bin, it was cheep anyway and go look for a better solution.

The other way is to make your own purpose built hardware solution out of a very fast MCU or a FPGA. However for single one off projects this tends to not be very economical once you consider the number of man hours to complete such a project. So once you factor in the cost of your time, it tends to be cheaper to just bit the bullet and buy the professional solution. Tho for this one the RS232 sounds like it would be easy to do with simply running it trough TOSLINK fiber cables (unless you have a requirement that it all has to go trough 1 single fiber)
 

Offline berke

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #8 on: January 23, 2024, 11:02:43 am »
Universal solution to everything, world peace, food crisis, cancer etc: use an rpi!!!! (sarc)
Sorry, no!

No need to get upset.

https://www.amazon.com/ASHATA-Converter-Conferencing-Conversion-Computers/dp/B081L9KLQ2

https://www.amazon.com/Singlemode-Transmission-Surveillance-Conversion-Transmitter/dp/B088PFXSXJ

Get the 4 channel version, use one channel for VGA, smuggle UART over the other two channels.

EDIT: Actually for UART what I said is stupid, it'll only work in one direction.  But the UART-to-VGA converter is interesting.  Depending on how the VGA-to-COAX-to-VGA device works, it might require microcontrollers for buffering and some analog circuitry for level shifting and generating the sync pulses.

How many fibers can you use?
« Last Edit: January 23, 2024, 11:16:15 am by berke »
 

Offline berke

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #9 on: January 23, 2024, 12:15:48 pm »
I think your best bet is a VGA-to-IP KVM extender and a pair of bidirectional fiber converters, however you probably need to run some crummy Windows software on the far end to access the remote device.  Unfortunately VGA is rare nowadays, it's easier to find HDMI-to-IP KVMs, and while HDMI-to-VGA converters are cheap the reverse is not true.  So it really depends on the details of what you want to do.

  https://www.startech.com/en-us/audio-video-products/ipusb2vga2

 

Offline spostma

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #10 on: January 23, 2024, 03:38:23 pm »
The Startech IPUSB2VGA2 is based on the EliteSilicon EST3868 chip, which is a gigabit Ethernet to 4-port USB 2.1 server,
coupled to a DisplayLink USB graphics card with VGA out.

We have used this combination for years in a medical device that runs the gigabit ethernet over a LC duplex fibre.
The box shown below is in fact an old but fancy desktop extender, and has a 4-port gigabit ethernet switch as well.

It works very well and is stable.  The only problem of this setup is that the EST3868 USB Server driver does not work well with newer Windows 10 updates.
If you work with an older Windows system I can send you a used but functional system; send me a PM if you want one.
It also has two free USB2.1 ports, so you can add an USB-to-serial converter yourself.
 
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Online SiliconWizard

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #11 on: January 23, 2024, 07:45:40 pm »
 
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Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #12 on: January 23, 2024, 09:12:34 pm »
foxboxrxvga

thanks, it looks *very* interesting  :D

I will try to contact them in order to understand the cost.
Hope Google will show some feedbacks.
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Online SiliconWizard

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #13 on: January 23, 2024, 09:22:42 pm »
foxboxrxvga

thanks, it looks *very* interesting  :D

I will try to contact them in order to understand the cost.
Hope Google will show some feedbacks.

Yes, it has exactly what you need apparently. I'm afraid the cost might be a bit prohibitive though for a personal project, you'll see.

Doing it completely from scratch is of course possible, but not trivial. The tricky part with doing it with off-the-shelf parts will be to mix the serial data with video over a single fiber.
Purely for video, using a VGA-HDMI adapter plus a HDMI over fiber transmitter, such as this: https://www.amazon.com/LornCeng-Extension-Uncompressed-Transmission-Singlemode/dp/B0BN536RN1 , would do for probably much cheaper than my above link.
 

Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #14 on: January 24, 2024, 12:45:07 pm »
it has exactly what you need apparently. I'm afraid the cost might be a bit prohibitive though for a personal project, you'll see.

Umm, it seems they don't sell to private beings, only to companies.
I will try-again, with local resellers.

Doing it completely from scratch is of course possible, but not trivial.

The biggest problem is to find a bidirectional OptoElectronic module and understanding which is the best data encoding.
That stuff can be handled in HDL, e.g. manchester encoding, vs ... something more specific.

Quote
VGA-HDMI adapter

I have done some experiments over the last few years with several VGA-to-HDMI adapters purchased on Amazon, most of them, especialy in the price range 10-20 euro, do not have acceptable video quality and suffer from several problems with colors and thermal stability.

In the end I found only one good VGA-to-HDMI converter, which works well in the long term, do not make the colors faded or distorted, but costs in the range of 40..50 euro.

So, ... I would avoid using it unless absolutely necessary.

The same thing for "VGA capture cards". As easy as it may seem, on a conceptual level, to pair one with a linux SBC, or a little board without an operating system, good luck finding one that has decent video quality, is well documented, and most importantly, comes with opensource drivers that are stable and clear enough to allow you to rewrite it for your final MPU application.

PCI stuff? Forget it!
USB stuff? Yes, it can be paired with modern MPUs with integrated USB, but... well, I have been reverse engineering a VGA-to-USB capture card for 2 years
  • costs ~90..100 euro on eBay, second hand
  • has very good VGA video quality, up to 1024x768, but only 30fps
  • has ZERO documentation, ZERO kernel support
  • has MacOS/x86 and Windows/x86 binary drivers only
  • has USB2 Full Speed compatibility
  • uses 3 different USB methods {bulk, isochronous, ...) to communicate
and this is the best of the various things I've tried, including VGA-USB for 20 euros which only have the good thing about being cheap  :-//
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Online mariush

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #15 on: January 24, 2024, 12:54:58 pm »
You can get a kvm over ip device for under $100 on eBay, here's a random example with hdmi , dvi-i (includes vga) , usb and audio over ethernet for ~ $75 : https://www.ebay.com/itm/285406835138
Don't know about rs-232 ... maybe there's some rs-232 to ethernet converter cheap, and then you just connect both this one and the kvm over ip to a 2/5/8 ethernet switch and the switch to a $10-20 media converter


example serial to ethernet : https://www.ebay.com/itm/403761948794

« Last Edit: January 24, 2024, 12:59:31 pm by mariush »
 

Offline berke

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #16 on: January 24, 2024, 01:12:01 pm »
The biggest problem is to find a bidirectional OptoElectronic module and understanding which is the best data encoding.
That stuff can be handled in HDL, e.g. manchester encoding, vs ... something more specific.
How about using five fibers and doing it the analog way?  Three fibers (R,G,B), one fiber UART TX, one fiber UART RX.  There are transmitter and receiver modules with fast rise/fall times that you probably can use in analog mode.  For UART you could directly use digital transceivers.  You'll probably need some "fast" "video" op-amps for level shifting.  Biggest problem could be TX/RX bandwidth not extending down to DC.  In that case a little bit of modulation might do the trick.  Given that the fiber transceiver bandwidths can be very high, a simple chopper on the TX end and low-pass filtering in the RX end (which can be integrated with the RX amps.)

- VGA input (R,G,B) → level shifting using fast op-amp → chopper → analog optical transmitter → analog optical receiver → low-pass filter → amplifier and level shifter → VGA output (R,G,B)
- RS232 input → RS232 receiver to get logic levels → digital optical transmitter → ...
- RS232 output ← RS232 transmitter ← digital logic receiver ← ...

Quote
In the end I found only one good VGA-to-HDMI converter
Care to share?  I'm interested, computer screens don't come with VGA ports anymore.  (And even HDMI is not guaranteed.)
 

Offline pcprogrammer

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #17 on: January 24, 2024, 01:17:35 pm »
You can get a kvm over ip device for under $100 on eBay, here's a random example with hdmi , dvi-i (includes vga) , usb and audio over ethernet for ~ $75 : https://www.ebay.com/itm/285406835138
Don't know about rs-232 ... maybe there's some rs-232 to ethernet converter cheap, and then you just connect both this one and the kvm over ip to a 2/5/8 ethernet switch and the switch to a $10-20 media converter


example serial to ethernet : https://www.ebay.com/itm/403761948794

For what I understand from it, is that this is only for transmitting the signal. You also need a receiver for the other end. The opposite goes for the foxboxrxvga solution SiliconWizard mentioned.

So this is also needed. https://www.ebay.com/itm/285406833768?hash=item427392ac68:g:f~sAAOSwuuFkxUSd

Making your own for VGA probably won't be cheap because you need very fast ADC's to capture the higher resolutions. ~125MSa/s for 1920*1080. This also means high speed handling to get it out onto the fiber. But interesting none the less  :-+

Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #18 on: January 24, 2024, 01:45:31 pm »
Care to share?  I'm interested, computer screens don't come with VGA ports anymore.  (And even HDMI is not guaranteed.)

Sure, it's the ‎StarTech VGA2HD2 (link here)
VGA+Audio => HDMI, made in 2012, video up to 1920x1200

Umm, checking on Amazon, it's now listed at ~€170 euro X_______X
Bought in 2022, I'm sure I paid ~50 euro, most likely during a BlackFriday or something.
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Offline pcprogrammer

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #19 on: January 24, 2024, 01:50:51 pm »
The biggest problem is to find a bidirectional OptoElectronic module and understanding which is the best data encoding.
That stuff can be handled in HDL, e.g. manchester encoding, vs ... something more specific.

Maybe this can do, but is gives surprisingly little information about how to hook it up. Guess the "Industry Standard 1×9 footprint package" should shed more light on it.

Edit: This one gives a bit more information.
Edit2: This is also interesting.
« Last Edit: January 24, 2024, 02:07:44 pm by pcprogrammer »
 
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Offline berke

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #20 on: January 24, 2024, 06:08:42 pm »
Purely for video, using a VGA-HDMI adapter plus a HDMI over fiber transmitter, such as this: https://www.amazon.com/LornCeng-Extension-Uncompressed-Transmission-Singlemode/dp/B0BN536RN1 , would do for probably much cheaper than my above link.
There are actually "HDMI fiber cables" that are cheaper than that, I have an 8m one, they sell 30m ones.

Rolling your own is an interesting project but it's not happening under $200 unless analog, and even then...

For starters if you go digital you're looking at a 1.13 Gb/s stream unless you want to compromise on quality.  That will need a mid-level FPGA with gigabit serdes'es to format the streams, maybe an ECP5 can do it.  If you implement 8b10b coding this becomes 1.41 Gb/s not counting overhead.

So count in two dev boards with enough differential I/Os for the ADCs, DACs and the transceivers, maybe $150 a pop?  If they are available, that is.  Pray you don't need any terminating resistors for your differential connections to get the particular kind of signaling the ~1.5 Gbps transceivers want, otherwise you'll have to spin a board.

To digitize the VGA you need a fast ADC or maybe 3 and an analog front-end and the layout can't bee too trash or you'll have disgusting ringing effects around edges.  At the other end you need 3 DACs and also analog front-ends for each channel and the same layout comment applies.  The UART is easy compared to the rest, you'll just slip it in the stream.

I don't even know how much the fiber itself costs.

Cheapest transceiver modules on Mouser start at 15 bucks.  Unless someone finds a full duplex one that'll be 4 modules at $60.  Not counting time obviously.

If you can use multiple fibers and the line isn't too long the analog route seems more feasible to me.

The cheaper transmitter modules use LEDs, those are quoted as having 10ns rise/fall times but that's for full scale, so the bandwidth should be enough for an XGA signal.  With proper readout PIN photodiodes can be pretty fast.  So you have a transconductance amplifier to drive the LED and a transimpedance amplifier at the other end and some level shifting, but it should go down to DC.  I don't even think you need a chopper anymore.  You may have to include some trimmers to adjust the signal levels so that the sync pulses have the proper levels.  You'll have a little bit of skew between channels so the edges may show some slight fuzzy coloring, but if you cut your fibers to within 10 cm this should be minimal.

If you go monochrome you can reduce the video signal to a single fiber.

Duplex on a fiber in analog would require a dichroic beam splitter at each end, you could use RGB cubes used in video projectors and RGB LEDs as a poor man's WDM, you do have two optical tables right? :)  Or maybe an optical circulator?  Digital you can do TDM.

On second thought, since the return channel is only used for 1 Mbaud UART, maybe a single beam splitter can do it, possibly by adjusting the timing of the UART signal w.r.t. the video signal (transmit during blanking kind of thing), this could be done with a small FGPA or maybe even a µC.

Another avenue could be something that converts VGA to RF, then you RF to fiber and back.

Would be nice if you gave us some more details about the constraints!
 
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Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #21 on: January 25, 2024, 07:02:01 am »
If you go monochrome you can reduce the video signal to a single fiber.

One of the video screens of the instruments I need to export is green-only, so something that should be { 1024x768, 4bit colors }.
However, for another session I need to export { 1024x768, 24bit colors}, each color has a meaning, so it can't be altered  :o :o :o
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Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #22 on: January 25, 2024, 07:06:47 am »
The serial should be 119200bps (less than the 1Mbps I said above, but) full duplex, as it needs to constantly transmits and receives data  :o :o :o
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Offline Nominal Animal

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #23 on: January 25, 2024, 08:28:31 am »
Ages ago, I experimented with UART over TOSLINK (i.e. up to 5m of plastic optic cable, 650nm LED), with one cable in each direction.  To keep the duty cycle closer to 50%, I reversed the polarity, so idle == LED unlit.  It worked just fine using TOTX173 transmitters and TORX173 receivers at a couple of Mbaud (I believe I used the Teensy 3.0 I got from the Kickstarter for the test).

The bad thing is, the connectors (TOTX1353(F) and TORX1353(F)) are about 10€ apiece nowadays at Mouser, and not easy to find at reputable sellers; but TME seems to have a small selection of the Cliff versions (OTJ-N and ORJ-N seem quite nice to me) at reasonable prices (~ 3€ apiece).

In comparison, you can get SFP+ transceivers (APSP85B33CDL03 from Mouser) for less than 20€ apiece.  However, you then need a PHY capable of generating the gigahertz signaling from parallel data (like XGMII), a video ADC on one end (like TI TVP7001PZP), and an FPGA to tie them all together; and then design the line code that can synchronize to the various pixel (scan row) video rates with the UART data interspersed, because your bit rate is basically constant.  A lot of work...

The SBC approach does look much simpler and more feasible.
 

Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #24 on: January 25, 2024, 10:11:07 am »
The SBC approach does look much simpler and more feasible.

Cannot be used, especially RPIs.

It's a complex question to explain, basically I got a written permission to conduct a couple of personal experiments in the laboratory, but you are not allowed to introduce *anything* that runs an unauthorized operating system. Even the laptop I can take with me to the lab has neither USB stick (1) nor hard drive, it boots from the LAN and can't access anything other than the local infranet. I'm not even allowed to take it out of the lab for the lunch/coffee breaks.

Anyway, supposing you can use a GNU/Linux SBC, well I would use my old friend PowerPC 4xx SBCs.
Why? Because that old guy is my personal "swiss knife" for all the tasks!

The SBC already comes with a built-in uart, and it also has two PCI@33Mhz independent slots (so, there is no PCI bridge between them):
  • slot1: you could plug a USB-EHCI, for -say- a VGA-to-USB grabber?
  • slot2: you could plug an optical fiber card
so ... job done?
Well, yes and no ...

It's "hypothetically speaking", as you can't bring this technology to the lab, but even if you could, well ... You still have the problem with the VGA capture.

As I said, most of USB-VGA-capture cards (especially cheap ones) are just garbage, HDMI-to-IP-grabbers are even worse, I've hacked a couple... forget them.
There are good Video grabbers out of there but tend to be "binary-only/x86", so ... again, forget them.

I haven't yet finished to reverse engineering the only one decent I found, which is EHCI and can be supported by a custom userspace application with minimal kernel driver needed, just a couple of patches on the USB engine: that's great, as it makes things elegant, quick, and portable, unfortunately the card is very expensive (>100 euro, second hand) and difficult to find on eBay.

Image, to acquire the video-camera, in the end I changed cameras, and I got one that has an HDMI cable set up supported by a special third party converter (+160 euro) that make the camera to be viewed in Linux as if it were a webcam/HD.

Just saying, I would avoid video grabbers like a plague.

(1) just crazy!!!
They desoldered them and filled the holes left by USB connectors on the laptop chassis with melted plastic.
So even if you hide a USB stick in your underwear, you can't physically insert it anywhere ='(
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Offline Berni

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #25 on: January 25, 2024, 10:40:01 am »
Well in that case you are forced into using a raw hardware solution.

Even the professional video over network solutions likely at the least run a RTOS inside it to handle the network stack. Those USB video capture dongles also tend to run a fair bit of firmware inside of them, fully possible there is a RTOS in there too.
 

Offline berke

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #26 on: January 25, 2024, 12:05:31 pm »
It's a complex question to explain, basically I got a written permission to conduct a couple of personal experiments in the laboratory, but you are not allowed to introduce *anything* that runs an unauthorized operating system. Even the laptop I can take with me to the lab has neither USB stick (1) nor hard drive, it boots from the LAN and can't access anything other than the local infranet. I'm not even allowed to take it out of the lab for the lunch/coffee breaks.

With these kinds of security concerns I'm surprised that you don't seem to have qualms about using random PLA-sponsored electronics off of Aliexpress.

Anyway, what kind of length are we talking about and are you willing to use multiple fibers?
 

Offline Yansi

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #27 on: January 25, 2024, 12:20:17 pm »
You could  convert VGA to SDI video over fiber.  Chinese guys sell even modules with some 485 sidechannel - not sure about features, never touched that thing.
 
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Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #28 on: January 25, 2024, 12:27:19 pm »
what kind of length are we talking about and are you willing to use multiple fibers?

approximately ~<1200m of cable
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Offline berke

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #29 on: January 25, 2024, 01:29:54 pm »
approximately ~<1200m of cable
With a 200€ budget??
 

Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #30 on: January 25, 2024, 01:39:41 pm »
approximately ~<1200m of cable
With a 200€ budget??

yup, I don't have to buy the optic fiber cable, there are already several "spools" (1000m, 2000m, different connectors) in the laboratory, and I can use them.
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Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #31 on: January 25, 2024, 01:44:06 pm »
I'm tempted to buy one of those toys on Amazon (224 Euros shipped from Shanzen) with the written promise at the time of purchase that I can "return" it if not satisfied because it doesn't conform to specifications.

However, I will definitely buy some optical modules, at least to make a synchronous fiber optic serial, just to learn.
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Offline Yansi

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #32 on: January 25, 2024, 01:49:02 pm »
Still, for 200€ you will barely buy the two SFP modules and accessories, not talking about other components, if you want to build it yourself.

For the VGA <--> SDI variant, it should be buildable on your own, but i would at minimum double your budget, maybe even tripple it. (And still not counting the hourly rate for developing it).

So, I really not see an issue building such a thing, the issue may be your expectations of price. 200€ is a price you could possibly buy a mass market solution (if one would exist), but you will definitely not buy the whole development for it.

Do not buy "some modules", buy the ones you could build the whole setup including the video. It will be cheaper than running two separate links, occupying two or more fibers.

As I've suggested, chinese folks sell the SDI<-->SFP fiber converters with some kind of RS485 support, all bidirectional over a one single-mode fiber (WDM).
For example this: https://www.aliexpress.com/item/1005005901467364.html
Plenty of solutions to convert SDI<>VGA (or other interface).

I am still not sure what u r trying to achieve here (have not followed that carefully), but have a feeling you are overthinking the required solution.
 
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Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #33 on: January 25, 2024, 02:18:10 pm »
have a feeling you are overthinking the required solution.

so, we have to transmit VGA and RS232 over 1000 meters away, and it must be done on optical fiber because it is an environment with very high electromagnetic pollution. There are big motors, coils and things that even require lead shielding.

How can you say - overthinking the required solution - when I clearly said that I have ZERO knowledge about the cost of optic things, as in this specific case, becasue I am paying with my own pocket for the whole things? (freelancer contract)

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Offline Nominal Animal

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #34 on: January 25, 2024, 02:45:28 pm »
Within the stated constraints, I do believe a video ADC like TI TVP7002 (HTQFP-100, 7.71€ at Mouser in singles, uses 3.3V and 1.9V supplies) combined with an FPGA is a must.  It is what is used in OSSC, the Open Source Scan Converter (low-latency video digitizer and scan conversion board used by many retro video game enthusiasts), and the video quality should be quite good.

VESA 1024x768 60fps mode uses a 48kHz VSYNC and 60MHz pixel clock (1344 pixels per scan line).  Basic 640x480 60fps has a 31kHz VSYNC and a 25MHz pixel clock.  These are all well within the TVP7002 capabilities.  TCP7002 is controlled using I2C, so you also need a small microcontroller to adjust configuration and parameters, while an FPGA selects the parallel RGB data to be sent, mixing in the UART channel(s), and uses a serdes or PHY (XAUI/SFI) to interface to a SFP+ fiberoptic module.

The serdes/PHY is a problem.  It converts parallel data to the GHz-range serial (differential) pair the SFP+ module uses, and vice versa.  Some FPGAs like Lattice ECP5 do have built-in serdes for 3.2Gb/5Gb for up to four lanes; you need two lanes, one in each direction.  Only the ECP5UM and ECP5UM5G series have the serdes, and they're BGA only, but they might be able to drive an SFP+ module directly (see here, XAUI mode).

Using a 10GBase-SX SFP+ module and layer 1 (I believe!) Ethernet (jumbo) frames for the data, for 38 bytes of overhead per 46-9000 payload data bytes, the data would be proper 10G Ethernet stuff you could route within a LAN.  If a few first bytes identify the payload, you can use the same format on both legs of the transmission.  Note that on the other direction, you do need to buffer some UART bytes, as the overhead is a bit much (8400%) otherwise; i.e. burst, instead of send/receive individual bytes.  I'd include a few header bytes in the payload, identifying whether it contains a full scanline (and if so, which scan row and frame/field number), and whether one or more UART payload bytes follow.  Or you could use UDP/IPv4 datagram(s) within the Ethernet frame, so different ports would be used for different UART connections, making the format IPv4-routable, and easier to extend (for example, more than one UART link).

Let's say you limit to a 1Gbits/second bandwidth instead.  The practical data bit rate including Ethernet frame overhead is about 800 Mbit/s.  This suffices for 1024×768 24bpp 30 fps (a little under 567 Mbit/s, plus framing overhead, plus the UART data).  This would require you to have a full framebuffer of about 19 Mbits (2.4 Mbytes), because the VGA input data rate is about twice that.  The other option is to transfer 60fps interlaced, every other scan line per field, so that only a few scan lines need to be buffered at a time, also leading to much lower latency; but also leading to tearing, since the odd and even scan lines would be from different consecutive display frames.  It would really be 1024×384 60fps, in other words..  The FPGA would act as the MAC, reading the TVP7002 parallel output selecting and buffering only the visible part of each scan line, while pushing the previous one a byte at a time at 125 MHz to a gigabit GMII PHY, followed by a media converter to fiber (1GBase-SX).

I think, that is.  I am not absolutely certain of any of the above, not having done it myself before; the FPGA part in particular is new to me.  The state diagram isn't complicated, unless you include stuff like mode autodetection; using a separate microcontroller to measure HSYNC/VSYNC and control and configure both the video ADC and the FPGA should make things much simpler, modular.
 
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Offline Yansi

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #35 on: January 25, 2024, 02:48:11 pm »
First, could you please tell us what is the end application?  Why do you need to transfer VGA video over such distances? This is rarely being done, as there are often better solutions around that problem. Extending video over such distances is rarely needed, hence the lack of quality mass produced solutions. Moving video over such distances is primarily only done in the video broadcast industry (which I am slightly familiar with, hence my quick SDI suggestion).

The other issue you have is your attitude dismissing all offered solutions, without giving a reason. So again, could you please be more specific about the application? We may then very well be more specific with suitable solutions to your problem.

For remote access to computers, there are much better solutions like remote desktop, to access remote PCs over the LAN/internet. But again, we do not know what is the source of the VGA (XGA 1024x768) video. Also, plenty of mass produced HW and SW solutions exist for transferring serial data over the LAN/internet.

Nobody is being angry, about your zero knowledge, people just may be irritated that you are denying offered help without providing further detail as of what is needed.

If this is a freelance contract, why are you paying with pocket money? Does not make much sense to me. Just make your contract in a way, they will pay for all including your time spent. I would never agree doing any contract work without being paid. Or did you mean a "hobby personal project" instead?



 
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Offline Yansi

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #36 on: January 25, 2024, 02:55:08 pm »
Within the stated constraints, I do believe a video ADC like TI TVP7002 (HTQFP-100, 7.71€ at Mouser in singles, uses 3.3V and 1.9V supplies) combined with an FPGA is a must.  It is what is used in OSSC, the Open Source Scan Converter (low-latency video digitizer and scan conversion board used by many retro video game enthusiasts), and the video quality should be quite good.

VESA 1024x768 60fps mode uses a 48kHz VSYNC and 60MHz pixel clock (1344 pixels per scan line).  Basic 640x480 60fps has a 31kHz VSYNC and a 25MHz pixel clock.  These are all well within the TVP7002 capabilities.  TCP7002 is controlled using I2C, so you also need a small microcontroller to adjust configuration and parameters, while an FPGA selects the parallel RGB data to be sent, mixing in the UART channel(s), and uses a serdes or PHY (XAUI/SFI) to interface to a SFP+ fiberoptic module.

The serdes/PHY is a problem.  It converts parallel data to the GHz-range serial (differential) pair the SFP+ module uses, and vice versa.  Some FPGAs like Lattice ECP5 do have built-in serdes for 3.2Gb/5Gb for up to four lanes; you need two lanes, one in each direction.  Only the ECP5UM and ECP5UM5G series have the serdes, and they're BGA only, but they might be able to drive an SFP+ module directly (see here, XAUI mode).

Using a 10GBase-SX SFP+ module and layer 1 (I believe!) Ethernet (jumbo) frames for the data, for 38 bytes of overhead per 46-9000 payload data bytes, the data would be proper 10G Ethernet stuff you could route within a LAN.  If a few first bytes identify the payload, you can use the same format on both legs of the transmission.  Note that on the other direction, you do need to buffer some UART bytes, as the overhead is a bit much (8400%) otherwise; i.e. burst, instead of send/receive individual bytes.  I'd include a few header bytes in the payload, identifying whether it contains a full scanline (and if so, which scan row and frame/field number), and whether one or more UART payload bytes follow.  Or you could use UDP/IPv4 datagram(s) within the Ethernet frame, so different ports would be used for different UART connections, making the format IPv4-routable, and easier to extend (for example, more than one UART link).

Let's say you limit to a 1Gbits/second bandwidth instead.  The practical data bit rate including Ethernet frame overhead is about 800 Mbit/s.  This suffices for 1024×768 24bpp 30 fps (a little under 567 Mbit/s, plus framing overhead, plus the UART data).  This would require you to have a full framebuffer of about 19 Mbits (2.4 Mbytes), because the VGA input data rate is about twice that.  The other option is to transfer 60fps interlaced, every other scan line per field, so that only a few scan lines need to be buffered at a time, also leading to much lower latency; but also leading to tearing, since the odd and even scan lines would be from different consecutive display frames.  It would really be 1024×384 60fps, in other words..  The FPGA would act as the MAC, reading the TVP7002 parallel output selecting and buffering only the visible part of each scan line, while pushing the previous one a byte at a time at 125 MHz to a gigabit GMII PHY, followed by a media converter to fiber (1GBase-SX).

I think, that is.  I am not absolutely certain of any of the above, not having done it myself before; the FPGA part in particular is new to me.  The state diagram isn't complicated, unless you include stuff like mode autodetection; using a separate microcontroller to measure HSYNC/VSYNC and control and configure both the video ADC and the FPGA should make things much simpler, modular.

Too complicated.  VGA ADC yes (use whatever of your liking), but instead of FPGA which is a huge development pain, use a suitable serialization chip, like GS2970 + GS2972 to convert video into SDI bitstream and then shove the data into an SFP module. You could use the ancillary packets to transmit your serial line within your video data stream.
The only drawback is you may need to scale or crop the XGA video resolution into something SDI compatible like HD (720p or 1080p). But you can already get off-the-shelf mass produced converters for that, heck even to convert then SDI into fiber. Again, depends on what the OP really needs. ((//EDIT: Not talking about cheap converters from Amazon. Plenty of secondhand broadcast grade equipment over ebay for reasonable prices).


//EDIT: those Semtech serializers are also BGA, but just 100 balls. Easy stuff, compared to the 381 ball FPGA.
« Last Edit: January 25, 2024, 03:02:44 pm by Yansi »
 

Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #37 on: January 25, 2024, 04:09:49 pm »
For remote access to computers, there are much better solutions like remote desktop

In this topic I never said that I have to access a remote computer!
I clearly wrote that I need to remotely export the VGA video output (of an industrial device, which is evidently NOT a computer), and a serial!
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Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #38 on: January 25, 2024, 04:24:10 pm »
The serdes/PHY is a problem.  It converts parallel data to the GHz-range serial (differential) pair the SFP+ module uses, and vice versa.

Very interesting post, thanks  :D

I think the PCB is *very* problematic for me with Ghz-Range differential stuff.
So, for me is, it's a red-flag, which sounds "forget it, cannot be done".

Instead, I will try some products from Amazon and Aliexpress, with the policty "try, keep or return".
Including some VGA-to-SDI-optic; SDI is new for me, it sounds interesting, but never used, so ZERO know/how, experience, etc.

For sure, I will play with some optic modules on a custom PCB, but for simpler stuff, like multiplexing some serial devices 9600..19200bps over an optical cable.
With 1-2MBps as final bitrate, it will be a simpler PCB, so 100% feseable for me, and also *very* useful as I seriously need something similar for an other future task.
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Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #39 on: January 25, 2024, 06:27:43 pm »
The other issue you have is your attitude dismissing all offered solutions, without giving a reasond you mean a "hobby personal project" instead?

Attitude .... what OP really needs ....well, in the first post I clearly wrote what I was looking for, and I specified that I was looking for someone who has already used these products or something similar.

The only reply dismissing the offered solution was agaist "use a RPI", which I then explained in details, replying to Nominal Animal.

I don't know SDI, and I didn't even reply to you "yes/no/maybe" becase in the meanwhile I am documenting about!
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Offline Yansi

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #40 on: January 25, 2024, 07:32:48 pm »
I think the PCB is *very* problematic for me with Ghz-Range differential stuff.
So, for me is, it's a red-flag, which sounds "forget it, cannot be done".

What is so difficult to route 2 cm (or 4/5" if you want) of two traces near each other? Even if it would not be impedance controlled or what not, it would more than likely work (although not recommended).

Your biggest enemy is the BGA package routing and soldering, not high-speed diff pairs. Those are easy.

For remote access to computers, there are much better solutions like remote desktop
In this topic I never said that I have to access a remote computer!
I clearly wrote that I need to remotely export the VGA video output (of an industrial device, which is evidently NOT a computer), and a serial!

No you did not state that. You did state you've had some "feel that you need" and that  you need to extend VGA in a "very noisy environment". Neither have you stated, what the signal source is, nor that it is an industrial application.

Than you claimed nothing can run unauthorized OS, so SBCs are forbidden - does not make any sense, unless it is a safety critical application, in which case I seriously doubt you should be building it with cheap chinese converter boxes or other non-safety-certified commercial HW or on your own. How are you then sure, that the off-the-shelf HW will not contain unauthorized SW, operating systems, or anything else of concern?

...and then you run scared from hearing about Gbps data pair on a PCB.  :-//

Not sure how better we could help, as you are being very secret about everything. A bunch of solutions were already thrown.

 
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Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #41 on: January 25, 2024, 08:50:11 pm »
No you did not state that. You did state you've had some "feel that you need" and that  you need to extend VGA in a "very noisy environment". Neither have you stated, what the signal source is, nor that it is an industrial application.

That's all you need to know!
And I didn't put any secret on the specifications and constraints!
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Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #42 on: January 25, 2024, 09:58:59 pm »
Than you claimed nothing can run unauthorized OS, so SBCs are forbidden - does not make any sense, unless it is a safety critical application, in which case I seriously doubt you should be building it with cheap chinese converter boxes or other non-safety-certified commercial HW or on your own. How are you then sure, that the off-the-shelf HW will not contain unauthorized SW, operating systems, or anything else of concern?

I seriously doubt there is a GNU/linux SBC in a cheap Chinese converter box, and even if it was, for sure it's not easily re-programmable (hackable?), so they can turn a blind eye.

But they can't turn a blind eye to any GNU/linux SBC that even a housewife would know how to use to save data on its internal SD card, used, among other things, to boot the SBC itself.

Something like this DOES not even enter the laboratory, they see it as a serious threat.

I found a Chinese MPU in the HDMI video capture device I opened last week, followed by a physical 100Mbps Ethernet. The MPU has enough power and ram to compress H26* and has a large internal flash-ROM to include the HS26* algorithm as well as a full TCP/IP stack. Not bad, unfortunately there is no jtag exposed, so it's not even worth wasting your time on, you couldn't do much with it anyway.

In case of need, they don't see it as a threat, they can exceptionally turn a blind eye.

I don't want to tell you too much, just, they made a logistical *BIG* mistake, and it takes time for them to fix it, in the meantime I don't want to sit around doing nothing. I need a temporary solution, which I am willing to pay out of pocket even to avoid finding myself overwhelmed by work commitments in the months immediately preceding the holidays, when they have solved the problem and managers who know nothing about what happened will expect nothing but the deadlines to be met.

you know, ... big companies ... anyway, for sure the final solution will be safety-certified (it must be), but I am the one who has neither to manage it nor to pay for it. It's not my business (and technically, I write software, I don't do hardware); what I need is to read a damn remote instrument, leaving it where it is at the moment, away from my desk, without the need to get close and damage my equipment, or worse still, hurt myself.

Cannot say a word more than this  :-X
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Offline berke

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #43 on: January 25, 2024, 11:12:22 pm »
I don't know what kind of job/contract you are in and I understand you can't give full details, but it sounds like it's not a technical problem you have.  My advice to you would be to forget the price, shop around and get a quote for a serious solution that will work (maybe $5k? $10k?) and will be available in a timely manner, and put it in a small proposal explaining what you want to do, how much money/hassle it will save and why.  This will cover your ass and you won't have to pay out of pocket, will allow you to buy equipment from "places that don't sell to individuals" and will make you good and shit will get done.  $10k should be a minor expense if not a rounding error in a place with 1200 m of linear space. heavy EMI, radiation and security requirements even if it's some kind of underfunded public lab.  I understand the temptation of just paying a couple hundreds out of your pocket to get something fixed especially in a technically interesting manner but it really doesn't sound like 200 is gonna cut it.
 
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Offline Nominal Animal

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #44 on: January 26, 2024, 05:26:50 am »
If I were you, I might take a risk with Primeda Telecom PMD-VGA-KVM-SC-N (Amazon UK, eBay UK, AliExpress); Shenzen vendor/manufacturer).

You do need to add an USB microcontroller to provide RS-232 or UART ports, likely via custom USB HID packets, which can handle 64000 bytes/sec per endpoint, but a Teensy 4.0 could handle that easily (with RS-232 drivers if you need proper RS-232 ports) for up to 7 UART/RS-232 ports.
 

Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #45 on: January 26, 2024, 12:43:01 pm »
@Nominal Animal
Yup, good idea! I think it's worth a try  :D
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Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #46 on: January 26, 2024, 01:11:26 pm »
but it sounds like it's not a technical problem you have

It depends on how we look at it.

In the first posts, I asked for direct experience with products in the cheap area, so in case it's not a request to solve a "technical problem", it's more "social engineering". Then I also considered the (hypothetical? (1)) case of making something, giving constraints and specs.

(1) which may make sense, if you have some idle months and want to make good use of (part of) the time learning something new.

My advice to you would be to forget the price, shop around and get a quote for a serious solution that will work (maybe $5k? $10k?) and will be available in a timely manner, and put it in a small proposal explaining what you want to do, how much money/hassle it will save and why. 

I've never dealt with administration, so I have no idea of the costs and how much money/hassle it will save, and how they will react to a proposal, but I can find out. It might even work, so it's worth trying it immediatly as "plan A"; at worst they tell me "no dice", and we stay on the "plan B".

Thanks  :-+

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Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #47 on: January 27, 2024, 01:33:07 pm »
I take this opportunity to study and experiment with SDI. In this case it's stuff I will play at home, so hobby/learning on a low budget.
May be also some SDI <---> fiber optic adapters, with some short, 2..4m, LC/LC or SC/SC patches.

I will probably buy on Amazon, "try: keep or return" policy, some HDMI-to-SDI, and SDI-to-HDMI adapters, to be used with BNC cables.
I already have an HDMI LCD made by NEC, and a VGA to HDMI converter, the one I mentioned, product/vendor, in one of my previos posts.

- - -

If they will agree to buy professional equipment (planA), it will be interesting to compare it with low-cost equipment  :D :D :D
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Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #48 on: January 28, 2024, 09:30:09 pm »
If I were you, I might take a risk with Primeda Telecom PMD-VGA-KVM-SC-N

Talking about other stuff, I found a colleague who had tried it before returning it on Amazon because - full of problems, especially the USB part, I don't reccomend it - so he summarized.

(this is the kind of information I expected to read when I opened this topic)

At this point I will avoid the  Primeda Telecom PMD-VGA-KVM-SC-N and move forward with other candidates.
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Offline Nominal Animal

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #49 on: January 29, 2024, 01:13:15 am »
full of problems, especially the USB part
It is likely limited to HID devices only, which is why I said you will have to do your own RS-232/UART to USB (HID) to RS-232/UART conversion.

I expect none to work with say a hub and/or USB-to-serial converters.

If I were you, I'd find out if the 'full of problems' means it did not work like your colleague assumed it would/should (with USB-to-serial converters and/or hubs), or if it means it does not work with a keyboard+mouse+vga combo.  If the latter, then fine; but I suspect it is the former, and nothing will work according to that criteria, I believe.
 

Offline pcprogrammer

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #50 on: January 29, 2024, 07:41:33 am »
It is likely limited to HID devices only, which is why I said you will have to do your own RS-232/UART to USB (HID) to RS-232/UART conversion.

Most likely the USB depends on a host at the VGA input end and devices on the VGA output end. The host will see it as a HUB device and enumerate what ever devices are connected to the other end.

To make it work with serial over USB you would have to use a host capable micro and have that be your serial converter at the VGA input side. A standard USB to serial device like the CH340 can be used on the other end.

A F1C100s could be used for this because it has USB host capability and the PHY is embedded. The only problem is the lack of documentation, but there is an open source Linux kernel available from which the code can be derived. I did it for the device side of the code.

Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #51 on: January 29, 2024, 10:03:15 am »
full of problems, especially the USB part
It is likely limited to HID devices only, which is why I said you will have to do your own RS-232/UART to USB (HID) to RS-232/UART conversion.

I expect none to work with say a hub and/or USB-to-serial converters.

If I were you, I'd find out if the 'full of problems' means it did not work like your colleague assumed it would/should (with USB-to-serial converters and/or hubs), or if it means it does not work with a keyboard+mouse+vga combo.  If the latter, then fine; but I suspect it is the former, and nothing will work according to that criteria, I believe.

Yup, I was tempted to use the USB part, not to carry keyboard/mouse(1), but rather to transport the serial stream.

Asking for more details about today's coffee break(2), he said that some USB keyboards (like scan3) didn't work, PS/2 to USB didn't work, and RS232-to-USB it did not work, so forget about the USB part, it's not very useful for my purpose.

I don't expect it to work with "sync-on-green"(3), there are already very few LCDs (like NEC's) that support it, but he also said that there were problems with some VGA cards(4) and video resolutions, so problems which manifested themself with various glitches, as if it occasionally lost synchronization.

That is bad, I need persistent synchronization on my end.

(1) there is no keyboard, and no mouse on the remote industial equipment. It's as if I were asking to add a keyboard and a mouse and a video camera on a cinema set. At most you can add an infrared remote-control to control the shot or set the property. I can't say much, but we are not too much far with the apparatus I need to remote.
(2) (a bit of humor here, but ...) I guess, we should stop talking about work stuff during breaks, otherwise they are not "breaks" but rather "work extensions" done at the coffee machine  :o :o :o
I'm tempted to take over the meeting room by force, like when a pirate makes a lot of loot on land. I wouldn't even be allowed to use the whiteboard, or technically even sit at the table. Those nice rooms are reserved for managers and QA staff, however in the entire open space there are NO meeting rooms reserved for consultants and workers! Therefore, we use the little sofa in the coffee-area as a meeting room. Things must change!
(3) used in SUN and SGI servers and workstations, during the 2000s era
(4) Matrox M1 and M2 worked, Voodoo2 didn't
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Offline Nominal Animal

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #52 on: January 29, 2024, 10:07:35 am »
It is likely limited to HID devices only, which is why I said you will have to do your own RS-232/UART to USB (HID) to RS-232/UART conversion.

Most likely the USB depends on a host at the VGA input end and devices on the VGA output end. The host will see it as a HUB device and enumerate what ever devices are connected to the other end.
Unlikely, for the bandwidth and response latency requirements.  (We're talking about the fiberoptic + two-USB implementation, specifically.)

With HID only, the VGA input end can be a simple USB 1.1 HID host device, and the bandwidth required much reduced, to 512kbits/s or less per endpoint.  It is very likely this information is transmitted during horizontal retrace when there is no video information, making the overall encoding rather straightforward; and reduces the latencies to where devices do not timeout erroneously.

Let's assume a typical 1024×768 60fps with reduced blanking (CVT).  There are 813×60 = 48780 horizontal retraces per second.  Horizontal total is 1184 pixels, with the horizontal sync starting at pixel 1072.  That leaves only 112 pixel clock cycles for synchronization and USB data, or less than ten percent of the VGA bandwidth.  Of the 813 scan lines, vertical retrace starts on scan line 771, so 60 times a second (17ms intervals) you have additional bandwidth.  This interval is borderline for mice and touch device HID events, and definitely problematic for high-speed USB 2.0.  (Users generally dislike curved movement being replaced with straight lines.)

While bit errors in the video don't matter much, USB doesn't really tolerate transmission errors, so while one pixel might take 18 or 24 bits, the same amount of bits is likely used to encode a single byte in some simple-to-implement error-correcting format.
 

Offline Yansi

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #53 on: January 29, 2024, 11:26:40 am »
As I've suggested before, ebay is full of professional video equipment. Dealing with weird video standards, like sync-on-green, a video converter like tvOne C2-2000 series can help. can be bought for even less than GBP 100. You can convert to whatever you want, including HD-SDI (if you buy the correct model, i.e. C2-2355).  Conversion from SDI to fiber is straightforward even for a diy-built HW (beware, highspeed data pairs needed, haha).
 

Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #54 on: January 29, 2024, 12:58:34 pm »
As I've suggested before, ebay is full of professional video equipment.

It's the same with HDDs, DSOs and MSOs: eBay is both full of garbage and professional equipment which are a true bargain, so it's good *if and only if* you already know what you are buying, and you know what questions to ask the seller to check in advance the status of what you are purchasing.

As I have repeted several times, I have zero experiences with VGA-extender, SDI, etc. and I don't even have an indication of the cost of similar professional equipment in "brand new" or "guaranted second hand" conditions.

I'm perplexed that a "VGA extender" doesn't work with some video cards and resolutions (XVGA) that should be supported. The Voodoo2 certainly doesn't work Sync-On-Green", yet I am told that glitches appear. Why? What does it depend on? What should be checked? The specifications say "compatible with XVGA", too bad then, when my colleague set the Voodoo2 to 1024x768@ 60Hz, things didn't work.

He tested at home with his computer and video cards, who knows if that VGA-extender would work in my case in laburatory ... I don't think we can introduce this level of uncertainty if we can have products that respect the specs they claim without surprise.

It's the same with DSOs ... you read "120Mhz of bandwidth", and .. then after 30Mhz you see your signal is already less than 50% ...
Those are fake/deceptiving specs, and I like that, at least about multimeters, DSOs and MSOs, you can search for some feedback in this forum  :-+

Dealing with weird video standards, like sync-on-green

Just mentioned, I don't need it. As I wrote, I am within standard "XVGA specs"
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Offline Nominal Animal

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #55 on: January 29, 2024, 01:11:25 pm »
Asking for more details about today's coffee break(2), he said that some USB keyboards (like scan3) didn't work, PS/2 to USB didn't work, and RS232-to-USB it did not work, so forget about the USB part, it's not very useful for my purpose.
Right; it sounds like a very limited USB implementation!

Question:
Do you actually need a hardware solution on both ends?
Or would it suffice for the VGA input side to be a hardware solution, with a fully-featured computer on the remote side?

You see, generating 1000Base-T (802.3ab) signaling and say raw Ethernet frames from an FPGA is feasible.  Then, stick e.g. TP-Link MC220L (or a pair), and you can use 1000Base-SX, 1000Base-LX, or 1000Base-LH fiber.  On the other end, you'd have a computer decoding and replying to the Ethernet frames.  You can even use one unmanaged switch in between (the switch must directly see both endpoints) without having to implement an IP stack at all.

I believe Intel EK-10CL025U256 (93€ at Mouser) might be a suitable development kit.  Details.  It is based on Intel Cyclone 10 LP, has GbE, ample HyperRAM for a couple of full framebuffers (at 1024×768 24bpp), plenty of 3.3V I/O pins (for the VGA input based on TVP7002, as well as level translators/isolators for UART, and/or RS-232 transceivers, on a 2×20-pin header, making "daughtercard" handling VGA and serial ports easy to build).  Again, the Open Source Scan Converter schematics would show how the VGA input with TVP7002 is done.  (The idea being that TVP7002 is self-clocking, and the FPGA only needs to be fast enough to read the digital inputs.  1024×768 60fps pixel clock is 65MHz, i.e. 24 bits of data every 15 nanoseconds.  It seems to be too much for the HyperRAM (142 MB/s, the blurb says it can do 100 MB/s), so only every other scan line per field could be transmitted, leading to tearing.  Essentially, it would combine the digitized video data and UARTs into Ethernet frames (jumbo frames, of say 4k to 8k bytes per frame) as the video is digitized.

Altera DK-DEV-10M50-A (185€ at Mouser) would be a surer opyion.  It is based on Intel MAX 10 (10M50D), with two GbE ports, HDMI output, lots of DDR3 RAM, programmable clock generator, two PMOD connectors with eight I/O pins at 3.3V logic levels (well suited for serial port level translators or isolators or RS-232 drivers), Cypress EZ-USB 2.0 (FX2LP), and a HSMC connector suitable for interfacing to TVP7002 (2.5V CMOS, input is 3.3V compatible).  (The connector itself is bloody expensive, though: 14€ in singles at Mouser.)

(2) (a bit of humor here, but ...) I guess, we should stop talking about work stuff during breaks, otherwise they are not "breaks" but rather "work extensions" done at the coffee machine  :o :o :o
Noooo... my favourite part of the work day: brainstorming with cow-orkers with hot beverages.

there were problems with some VGA cards(4) and video resolutions, so problems which manifested themself with various glitches, as if it occasionally lost synchronization.
That's why I like the TVP7002 –– if its image quality is sufficient; it is not the best available, I understand, but just sufficient ––: it has been found to work with a lot of older equipment (see scan converter!), and you can fine-tune the details over I2C to get the best image quality possible, but it really handles the sync stuff itself.  (It would be a good idea to also wire the hsync and vsync outputs to the FPGA, so it can look at the intervals and polarity to determine the most likely VESA mode.  I would also allow the remote end to tune the I2C parameters.)

The DK-DEV-10M50-A has so much DDR3 RAM it can buffer entire video frames and queue many Ethernet jumbo frames, and even dynamically adapt the video frame rate to the available bandwidth (for example, if you want to also provide many Mbaud serial connections in parallel, and they all happen to transfer data at the same time).  Or "lock" to an integer fraction of the original, perhaps, for a "smoother" user experience.

Oh, and I do recommend considering using UART isolators in any case: TI ISO6721 oir ISO7721 for RX+TX only, ISO6742/ISO7742 for RX+TX+RTS+CTS; plus an isolated DC-DC converter if powering an RS232 transceiver on the isolated side.  The reason is that the VGA connector ground may not be exactly the same potential as the UARTs/RS-232 –– heck, they might even be connected to different machines, couldn't they –– and this way your FPGA board could share the VGA ground.

I'm perplexed that a "VGA extender" doesn't work with some video cards and resolutions (XVGA) that should be supported.
Although VESA defines a precise set of display mode timing information (see e.g. this), not all displays conform to them.  There is even a "sub-standard", "CVT" or reduced blanking, which greatly reduces the retrace durations.  Some devices might have soft or glitchy sync pulses.  Many VGA monitors do support EDID (via DDC2B, based on I2C), which the graphics card could easily parse and adopt its settings accordingly; very few VGA extenders bother to support that, because they'd really need to read it first from the remote end, before the local end queries it.  I don't think I2C clock stretching to cover a fiberoptic data transfer twice plus the actual query, would work well.
 
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Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #56 on: January 29, 2024, 01:11:59 pm »
@Nominal Animal
Speaking during lunch break, I heard that another colleague purchased a RS232/2ch <---> fiber optic converter that works very good!
You cannot transmit any break, but it's OK as I don't need it, so I think I will try it and buy a pair.

It's a bit costy, 90 euro each, but they come with two channels in a strong metal case, LC or SC, and each channel supports up to 1Mbps full duplex, so that's more than good!

There are no problems using two fiber optic patches, one for the video, the other for the serial. If it simplifies the "product search" thing, that's fine too, as the conduit would allow up to 8 fiber optic patches to pass through, so there's all the space you need  :D
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Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #57 on: January 29, 2024, 01:22:41 pm »
Do you actually need a hardware solution on both ends?
Or would it suffice for the VGA input side to be a hardware solution, with a fully-featured computer on the remote side?

umm, in theory it could be possible. I mean, it needs to be approved, but it is possible.
Just, I guess it must be a PC, rather than a SBC.

(2) (a bit of humor here, but ...) I guess, we should stop talking about Noooo... my favourite part of the work day: brainstorming with cow-orkers with hot beverages.

Indeed  :D

Think that the colleague with whom I have mini-meetings in the bar area is Norwegian and tells me that in his area even consultants have open space meeting rooms because brainstorming with cow-orkers is a very useful activity.

He is not allowed to enter my laboratory, I am not allowed to go up to his floor, we can only discuss at the bar, or in the open space area, or in the canteen area.
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Online SiliconWizard

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #58 on: February 03, 2024, 08:41:20 pm »
(...) even consultants have open space meeting rooms because brainstorming with cow-orkers is a very useful activity.

I'd think brainstorming with cow-orkers is moo.
 

Offline Nominal Animal

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #59 on: February 03, 2024, 09:35:00 pm »
(...) even consultants have open space meeting rooms because brainstorming with cow-orkers is a very useful activity.

I'd think brainstorming with cow-orkers is moo.
One reason I like to use the form cow-orker is that very often, "colleague" sounds very close to "colic".  Coincidink?  I think not.
 

Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #60 on: February 04, 2024, 11:27:02 am »
I'd think brainstorming with cow-orkers is moo.


Code: [Select]
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Have you mooed today?

sorry, I am afraid my post contains one involuntary little "easter egg:-//
Kind of "lapsus", peppered with self-irony (I am a coworker, too)
which sounds like it sounds because it's how it sounds when managers talk about.
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Offline berke

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #61 on: February 04, 2024, 11:37:16 am »
sorry, I am afraid my post contains one involuntary little "easter egg:-//
Kind of "lapsus", peppered with self-irony (I am a coworker, too)
which sounds like it sounds because it's how it sounds when managers talk about.
So how's it going?  Keep us posted!
 

Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #62 on: February 04, 2024, 12:17:57 pm »
One reason I like to use the form cow-orker is that very often, "colleague" sounds very close to "colic".

I think "colleague" is used more often referring to people who work in the same field but not for the same institution/work agency, whereas "coworker" tends to be used for people who share a workspace or duties.

Two freelancers in different squads (i.e. dev-team, testing-team, QA-team) are "colleagues"!
Are two freelancers in the same squad "colleagues" or "coworkers"?

mumble  :-//

Well, personally, I think the difference that is created between freelancers is when there is a form of (toxic) competition, i.e. they tend to point out your mistakes in the eyes of managers, in order to obtain other assignments, and therefore invoice more.

That's when "colleague" sounds very close to "colic". But usually it doesn't happen among people in the same squad, when they all work on the same contracts.

(so, money, more than personal Ego, is the real problem here. I think)

Behind the humor of the previous post, there is instead the fact that sometimes for managers, it doesn't matter what you would call yourself and people around your desk, because whatever you call it { co-lleagues", "co-workers }, managers only hear the first two letters, so for them it always sounds like "COws in the field, to be milked for milk:o :o :o

The opposite of courage is not cowardice, it is conformity. Even a dead fish can go with the flow
 
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Offline DiTBhoTopic starter

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #63 on: February 04, 2024, 12:30:19 pm »
So how's it going?  Keep us posted!

On Wedsday I spoke to the administration, who understood nothing, except that the problem sounds caused by two groups who didn't speak to each other, one reasoned in meters, the other in inches, with the result that when they assembled everything, it was us in the laboratory who realized that there is no space for a human being who has to work closely with the equipment.

Here the need to remotely export the VGA and the RS232 signals.

It took me two hours just to make them understand  :horse:

Now they have to have a meeting, which will be followed by another meeting... So I contacted the company mentioned in the first posts, which does serious equipment but absolutely does not sell to private individuals.

They will send us a quote and it may be taken into consideration.

I also ordered a couple of devices (including VGA-2-SDI, and SDI-2-HDMI, but also VGA+RS232-to-LC, and LC-to-VGA+RS232) from Chinese companies on eBay. With the agreement to pay in advance, try it and if you are not satisfied I will send it back at my expense for a full refund.

I'm also considering self-building, following Nominal Animal's instructions.

We will see  :-//
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Offline berke

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #64 on: February 04, 2024, 01:56:34 pm »
On Wedsday I spoke to the administration, who understood nothing, except that the problem sounds caused by two groups who didn't speak to each other, one reasoned in meters, the other in inches, with the result that when they assembled everything, it was us in the laboratory who realized that there is no space for a human being who has to work closely with the equipment.

Here the need to remotely export the VGA and the RS232 signals.

It took me two hours just to make them understand  :horse:
:) How many kick-off meetings does it take to change a lightbulb?
 
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Online SiliconWizard

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Re: VGA, RS232@1Mbps on optical fiber
« Reply #65 on: February 04, 2024, 09:53:16 pm »
And don't forget the wrap-up meeting once the lightbulb has finally been changed (or maybe it ended up not being changed for various reasons, and you'll want to analyze those reasons in a meeting for 4 more hours.)
 
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