GBS-8220, 23DB Connectors and Leads

[rare_j]

Here's someone else who's doing interesting things with the gbs, custom firmware to do proper 240p\288p

http://shmups.system11.org/viewtopic.php?f=6&t=52172

[Higgy]

@jbenam - the 8220 just has two VGA outputs. I guess a shop may find displaying the same output twice handy. I have the 8220 only because I found it cheaper.

@stedy - comprehensive list! I have the V3 board.

[Higgy]

Originally Posted by rare_j

Here's someone else who's doing interesting things with the gbs, custom firmware to do proper 240p\288p

http://shmups.system11.org/viewtopic.php?f=6&t=52172

I just read this many thanks. I was not quite sure if the RPi actually alters anything yet on the GBS that stays after powering off, or that it currently just mods things on the fly.
As he is talking about future work being able to flash firmware, or is it that he wants to make flashing easier? After flashing the Gotek, using a RPi to flash GBS should be ok

It sounds like at the moment you would need Amiga-Rpi-GBS-Monitor.

[amigappc]

What about this info:

http://stuffprojects.free.fr/index.p...d=23&Itemid=29

Old boards? any experience with those? Any other working solution without artifacts on screen?

Also, i found this one:

HD9800 Arcade Game RGB

Any difference?

[rare_j]

Originally Posted by Higgy

I just read this many thanks. I was not quite sure if the RPi actually alters anything yet on the GBS that stays after powering off, or that it currently just mods things on the fly.
As he is talking about future work being able to flash firmware, or is it that he wants to make flashing easier? After flashing the Gotek, using a RPi to flash GBS should be ok

It sounds like at the moment you would need Amiga-Rpi-GBS-Monitor.

I think it's not clear but from what I can gather he's got the Pi hooked up only to change the gbs's firmware. The Pi is a red herring, he could be using anything to reprogram it and it is not part of the chain.

If all the clever people looking at this cheap little board teamed up, awesome things could happen!

[Higgy]

Originally Posted by rare_j

I think it's not clear but from what I can gather he's got the Pi hooked up only to change the gbs's firmware. The Pi is a red herring, he could be using anything to reprogram it and it is not part of the chain.

If all the clever people looking at this cheap little board teamed up, awesome things could happen!

I have had time to digest the info.
The jumper across the GBS puts it into a programming mode and the RPi bypasses the firmware that the manufacturer runs (Gonas?) And the RPi talks directly to the video processor chip.

A bit like bypassing all the Amiga's chips just so you can utilise the CPU.

I guess you could make your own PCB and solder on the video processor chip, but that is going to be lots of work and very expensive. Easier to utilises the GBS and install custom firmware.

Fingers crossed the boffins workout how to write over the manufacturers firmware.

[amigappc]

@higgy Do you think RPI is just temporary middle step, or it would be needed permanently?

[Stedy]

Originally Posted by rare_j

Here's someone else who's doing interesting things with the gbs, custom firmware to do proper 240p\288p

http://shmups.system11.org/viewtopic.php?f=6&t=52172

I saw this when I was hunting for the programming documents.
Looks interesting, need to analyse the shell scripts a little bit further.

The Raspberry Pi is a command interpreter that interfaces to the TV5725 chip via the I2C port. I2C was developed by Philips for consumer applications and is quite popular for video chips, I have used it extensively.

An Arduino or PIC Microcontroller could be used to tweak the I2C settings in the TV5725 device. I2C will work with multiple masters, if everyone is quiet occasionally

I've been developing video systems since 2006 for the aerospace industry. Have spent time fault finding and developing complex systems and resolving video quality issues. Working with the GBS82XX takes time as I have to understand it, measure it, try a tweak, then see how it works and what else I may have affected. It's fun!

[Higgy]

Originally Posted by amigappc

@higgy Do you think RPI is just temporary middle step, or it would be needed permanently?

Unfortunately it is currently needed permanently. Sounds early days yet though.

[amigappc]

Originally Posted by Higgy

Unfortunately it is currently needed permanently. Sounds early days yet though.

Well, not so good solution then. There is no way to send exact required values to those China guys who manufacture convertor in order to apply it in some other revision?

[Vot]

Originally Posted by Stedy

Hi,

@Higgy

What board revision do you have?

@thread

This is the list of tests I'm working through on the GBS82XX:


* Measure the +5V current using current probe and DMM
* Measure the on-board 3.3V supply ripple, FFT DC to 200 MHz.
* Feed in 3.3V LVTTL sync signal, see what happens, does noise go away?
* AC couple video, 220uF capacitors before termination/potentiometers.
* Test LM1881 see what happens.
* Try CGA from the Amiga.
* Feed in composite PAL video signal to Y of YPbPR input, is the image stable?
* Feed CVBS into Sync input.
* Use VGA input feed Amiga video but set ID pins.
* Feed in composite NTSC video signal to Y input. Use NVidia card + drivers to set this
* Measure Nintendo Wii YPbPr signal, then feed it into the GBS-8200 or hack NVidia card to output YpBPr.
* Locate the LLC or Genlock clock, see what frequency it is with video fed in.
* Check SDRAM scan conversion signals
* Buy and try a LMH1980 http://www.ti.com/product/lmh1980
* Build a RGB + Sync to YPbPr circuit, http://www.linear.com/solutions/1311
* Prototype SCUTA CPLD for sync maybe required.
* Add scanline generator?

Quite a list, when I'm done, which won't be soon, I'll publish the list either on my website or Wordpress blog.

I have changed one component on the board, as the 1.8V power supply was borderline stable. The sync signal
does affect, the Amigas 5V CMOS is not compatible with 3.3V LVTTL!
Now I have the software manual, I'll be able to play. The last video chip I worked with, took about 150 hours to understand,
the GBS boards have a lot in common with what I am familiar
with, so I know where to tweak first.

Have not done much testing with games yet, static video test patterns are good for colour/focus/flickering.

Great work your doing. With any luck you guys will find out the cause and i will buy one

[dooklink]

Originally Posted by Higgy

I just read this many thanks. I was not quite sure if the RPi actually alters anything yet on the GBS that stays after powering off, or that it currently just mods things on the fly.
As he is talking about future work being able to flash firmware, or is it that he wants to make flashing easier? After flashing the Gotek, using a RPi to flash GBS should be ok

It sounds like at the moment you would need Amiga-Rpi-GBS-Monitor.

Hi All. I'm the one working on a custom firmware for the GBS82XX boards. There are some intresting theories on the cause of the 50Hz issues in this thread, some of which I wouldn't mind an explanation of the rationale.

I believe it should be posible to flash a cfw to the MTV230M (intel 8051 / MCS51 core) microcontroller. I've recently got assembly code running on it and I am now working on using the SDCC C compiler to try understanding the OSD generating hardware.

If you would like coordinate our efforts let me know, but I'm not too confident in the quality of my work, it's only a hobby project really.

I'm thinking of adding some info about the development tools I'm using on the Shmups forum including things like:

- SDDC C compiler
- sdas8051 assembler
- sdld linker
- S51 simulator
- Python scripts for ISP Flash R/W

[Higgy]

Hello @dooklink.

Your efforts have certainly got noticed. All GBS owners hope there is a killer bit of hardware lurking on the PCB ready to make their AMIGA/Retro hardware shine on LCD!

I can't speak for all of us, but it might just be @Stedy that can provide any tech help.

I have hardware; GBS, RPi, Arduino etc. My experiences are in more flashing firmware than any programming, and I mean following instructions that the boffins have devised not working out how to do it myself! (I think I have flashed most of my home electronics incl. the car!).

There are lots of passionate owners on here, and I am sure we will do all we can to help in this interesting project.

So far we have had 'recapping the board' & 'decent PSU' - Red herrings it seems.

Fingers crossed.

[jbenam]

Originally Posted by Higgy

@jbenam - the 8220 just has two VGA outputs. I guess a shop may find displaying the same output twice handy. I have the 8220 only because I found it cheaper.

Oh yes, I know that - I meant if there are any more differences other than that

[rare_j]

Thanks for posting here dooklink. I think quite a few people are following this with interest now.

A question for anyone who might know: can the components in use on this board theoretically handle an s-video input?

[dooklink]

Originally Posted by rare_j

Thanks for posting here dooklink. I think quite a few people are following this with interest now.

A question for anyone who might know: can the components in use on this board theoretically handle an s-video input?

No, I don't believe S-Video or CVBS are possible. You would need analogue (or digital) decoding of the signal to YPbPr or RGB as the TVIA Trueview 5725 doesn't have NTSC or PAL decoding.

[rare_j]

Thanks for the reply, I always forget that s-video is PAL or NTSC encoded and it makes sense that this board wouldn't handle that.

[amigappc]

What do you say about this, would this work:
[ Show youtube player ]

more details here (C64)
http://www.commodoreserver.com/BlogE...4A104C65DB541E

Connect Composite to vga with this adapter, or RGB ->Svideo->VGA on amiga? I know best would be to convert RGB signal to VGA directly, but just thinking about other non-flickering possibilities?

Regards,

[amigappc]

@dooklink & @Stedy Any progress with GBA-8200? Should I buy one of there already? If yes, which version (firmware) to llok for? Which power supply? Where to look, on e-bay? I ask because of international delivery.

[Higgy]

Originally Posted by amigappc

@dooklink & @Stedy Any progress with GBA-8200? Should I buy one of there already? If yes, which version (firmware) to llok for? Which power supply? Where to look, on e-bay? I ask because of international delivery.

@amigappc - I used ebay, bought straight from China. You could aslso try Aliexpress.

I don't think firmware version will matter much because it is going to get bypassed

I took out my RPi from my bartop arcade and am having a go. I have the programme booting but so far I see @dooklink's menu but no AMIGA

Note - there were no header pins where @dooklink connects so I had to remove the solder at the points on the pcb and solder in some header pins.