OSSC (DIY video digitizer & scandoubler)

[BuckoA51]

No need to convert RGB SCART to Component for use with this board it accepts RGB natively.

[meneerbeer]

How did you get the EP4CE15 into KiCad? Are there any quick tricks to it? I am kind of reluctant to fill in 144 pins by hand. With my own board I was lucky someone else already made a symbol and package for Eagle, but I want to be able to move to different FPGAs some time.

[marqs]

How did you get the EP4CE15 into KiCad? Are there any quick tricks to it? I am kind of reluctant to fill in 144 pins by hand. With my own board I was lucky someone else already made a symbol and package for Eagle, but I want to be able to move to different FPGAs some time.

I used this component generator to generate the symbol and connection info, which is probably a faster way than Kicad's builtin editor. For the footprint, I just modified a generic QFP-144 footprint to include a bottom ground pad.

I've almost assembled the first board, so I'll know in a few days if everything went fine...

[meneerbeer]

How did you get the EP4CE15 into KiCad? Are there any quick tricks to it? I am kind of reluctant to fill in 144 pins by hand. With my own board I was lucky someone else already made a symbol and package for Eagle, but I want to be able to move to different FPGAs some time.

I used this component generator to generate the symbol and connection info, which is probably a faster way than Kicad's builtin editor. For the footprint, I just modified a generic QFP-144 footprint to include a bottom ground pad.

I guess that is not too bad. I see that Altera provides .txt files with device pinout, so with some processing it should be possible to import that into that generator.

I've almost assembled the first board, so I'll know in a few days if everything went fine...

Good luck! I hope it works.

One thing I have been wondering about: linedoubling 240p results in an output image with 526 lines, I think. How is compatibility with TVs for that? I guess linedoubled 480i fits the best in the 480 spec, if not perfectly? Are there 858 samples per line?

[BuckoA51]

Regarding the HDMI issue, I came across this recently..

http://www.misco.co.uk/product/200886/L ... -Converter

The availability of that converter allows you to go with DVI out and still give people an option of HDMI + Audio if needed. Not ideal, but better than paying an obscene amount for the HDMI license.

[marqs]

One thing I have been wondering about: linedoubling 240p results in an output image with 526 lines, I think. How is compatibility with TVs for that? I guess linedoubled 480i fits the best in the 480 spec, if not perfectly? Are there 858 samples per line?

Yes, "240p" is typically 262 or 263 lines (or apparently 264 with Neo-Geo), so linedoubled output is +-1 line off the 525-line standard. I haven't yet encountered a display where that would be an issue - for example Panasonics seem to accept +-2 line deviation. 480i linedoubled is exactly 525 lines, so that's most compatible as you said. I'm using 858 samples per line with SCART and YPbPr inputs for linedoubled 240p/480i and 480p, and 800 samples with VGA input for 640x480. The samplerate is fairly easy to change, so it's possible to provide tweaking options for those whose displays have some tolerance. For example, I think the standard 800 samples per line would not be most optimal for Dreamcast's VGA.

[marqs]

Regarding the HDMI issue, I came across this recently..

http://www.misco.co.uk/product/200886/L ... -Converter

The availability of that converter allows you to go with DVI out and still give people an option of HDMI + Audio if needed. Not ideal, but better than paying an obscene amount for the HDMI license.

Yeah, that'd be a good option for those who don't route audio directly to an AV receiver. It's too bad that DisplayPort is such a rarity among TVs

[meneerbeer]

The samplerate is fairly easy to change, so it's possible to provide tweaking options for those whose displays have some tolerance. For example, I think the standard 800 samples per line would not be most optimal for Dreamcast's VGA.

That is correct. Dreamcast outputs at 480p timings, so there are 858 pixels (or something close to that, have not checked) per line. Only about 640 pixels contain video data. Most monitors do not like 480p over VGA and they cram the picture with part of the borders into a 640x480 area.

[marqs]

The first test board is now complete, and the blocks seem to be mostly working. Unfortunately, it seems that analog side of TVP7002 got somehow damaged during soldering as blue channel is completely missing and there's some noise. Otherwise, sync is stable and the board was even able to output 1080p coming from PC via VGA. I'll need to look more closely into that TVP7002 or perhaps build another board with more care. Then it's possible to say if everything really works or not... Anyway, below is a photo of the complete board for those interested to see it how it looks. I'm currently using a cheapo remote for control but the system can be programmed to support any remote using NEC protocol.

[emphatic]

Neat! The red button cycles output res or input select?

[marqs]

Neat! The red button cycles output res or input select?

It's the power button. All other controls are handled via remote.

[invzim]

Neato! What do you do for control, softcpu or a MCU?

[styrmling]

http://www.youtube.com/watch?v=m4xIy1rlJKs&t=0m15s

cant't wait to try one out.

[juji82]

looks hot!

[BuckoA51]

Absolutely stoked for this.

[marqs]

Neato! What do you do for control, softcpu or a MCU?

I'm using Nios II softcpu as it's sufficient for handling the control tasks. The only downside is that it eats away the block memory of the FPGA which could be used elsewhere, and there's not enough free pins on the QFP package to use external memory.

[Marmes]

Hi!

I followed this thread, found it quite interesting. Does this chip have internal memory?
What is the state of this?

[marqs]

Hi!

I followed this thread, found it quite interesting. Does this chip have internal memory?
What is the state of this?

The FPGA has a small amount of volatile memory for line buffers, logic, software etc. There's also a flash chip on-board, which contains the FPGA bitstream (firmware) which is automatically loaded when the system is powered on. The flash could also be used for storing various user settings.

As for the state, I'm still debugging the single-board prototype. The manufacturing quality of the PCBs was worse than in the first prototype so I've had difficulties getting the large, thin-leg ICs soldered reliably on the board. I've also been busy with other stuff during the last few weeks so I haven't had that much time for this project.

[FinalBaton]

just added this thread to my bookmarks. Very interesting project!
Would be interested in purchasing one, too.

[marqs]

I finally found out the root cause of the noise issue on the PCB. KiCad's automatic ground plane generation extended the plane too near to a signal trace, ignoring design rule constraints. This resulted to a short circuit on the manufactured PCB, effectively grounding one of the HDMI data wires. I managed to cut the short with a knife, and the board is now working without any major issues . I still need to design a slightly revised PCB as there's also a number of small improvements needed, but next I can concentrate on putting the firrmware and features together.

I'm planning to buy a SC-512N1 capture card, so soon I should be able to upload some videos showing the video output quality of the board.

[Konsolkongen]

Great that you worked out that bug. Looking forward to seeing more screenshots of this thing in action!

[BuckoA51]

Exciting times ahead!

[thesteve]

i have been contemplating something like this, but have no CPLD experience
my thoughts were slightly different, but so close it would be better to brainstorm
my thoughts
240P input
line trippled
optional blank 3rd line (scanline mode)
2 line buffers spec pixel width for 720P 60
the process.....
input V-sync
buffer 1 loads at 15K input scan line 1
at H-sync input switches to buffer 2
output active
out reads buffer 1 at 45K scan rate
at input Hsync buffers swap
total lag is 1 line (1 input line)

[marqs]

i have been contemplating something like this, but have no CPLD experience
my thoughts were slightly different, but so close it would be better to brainstorm
my thoughts
240P input
line trippled
optional blank 3rd line (scanline mode)
2 line buffers spec pixel width for 720P 60
the process.....
input V-sync
buffer 1 loads at 15K input scan line 1
at H-sync input switches to buffer 2
output active
out reads buffer 1 at 45K scan rate
at input Hsync buffers swap
total lag is 1 line (1 input line)

That's pretty much how I've implemented the linetriple mode. A few tricks are also needed in order to display 4:3 image in 1280x720 area, but they are relatively easy and do not require extra line buffers.

[thesteve]

i didnt see you had a line triple mode
anyway 4:3 is just a null count at the start and end of each output scan

so whats the status?
i was hoping to implement something like this into internal system mods, possibly with component output instead of HDMI

[marqs]

i didnt see you had a line triple mode
anyway 4:3 is just a null count at the start and end of each output scan

Yes - output pixel clock is set 3*(4/3) = 4 times the input sampling clock in the most straightforward setup (960 samples of active video each line) so that start and end can be filled with black pixels while keeping horizontal scan rate 3x the input.

so whats the status?

There's info on the status on some earlier posts - currently I'm working on the PCB, and then there's also work to do on verifying/improving compatibility with some systems.

i was hoping to implement something like this into internal system mods, possibly with component output instead of HDMI

Wouldn't VGA be a better choice for an analog output?

[bobrocks95]

I for one am hoping it's possible for both a VGA input and output, with HDMI (well, DVI considering those licensing fees) output as well. Switching to analog output for interlaced stuff would be a nice option to have over the quick deinterlacing.

[thesteve]

Wouldn't VGA be a better choice for an analog output?

VGA is a good output, but component makes is compatible with more TVs
the biggest need for this is that 240P is unsupported or badly supported by too much of the newer sets
current scalars wait 2X V-Sync before they even try to form an image and use a MPG algorithm to produce it
this looks ok on a natural looking image, but on high contrast pixel art (games) it causes artifacts and image softness

[HDgaming42]

Wouldn't VGA be a better choice for an analog output?

I think it would. Why compromise quality at this stage of the game? Although VGA input is getting rarer, it is far more likely your TV will mangle a VGA input less than a component one.

This isn't exactly a mass-market device where you need to cater to the lowest common denominator. To consider analog output at all, I'd throw my vote behind VGA as opposed to component. My two cents...

[Xyga]

VGA is better yes, but proper VGA>anything conversion can be a bitch (you need the right transcoder/converter and additional power slot).