Author Topic: VGA, RS232@1Mbps on optical fiber  (Read 6431 times)

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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.


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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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