Building my custom UZEBOX: Some newbie questions

Topics regarding the Uzebox hardware/AVCore/BaseBoard (i.e: PCB, resistors, connectors, part list, schematics, hardware issues, etc.) should go here.
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doragasu
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Joined: Fri Apr 01, 2011 10:42 am

Building my custom UZEBOX: Some newbie questions

Post by doragasu »

Hi all!

I heard about this console some time ago, and finally I decided to build my own, but I have some questions. I want to make it small, so I'm going for SMD parts. Is there a problem with this? Do overclocking cause problems with QFP atmega parts?

About the microcontroller: atmega644 or atmega1284? Is atmega128 fully compatible? Are the extra 64 KiB used by some games/applications?

About the controller connectors: I want to use SNES pads. Is the best way to get the connectors buying multitaps in eBay/Cash Converters, etc.? Do you know of anyone selling spare connectors?

I'm only interested in RGB output, so I'll remove the AD725 chip, and I'll output the video using the Sega Genesis/Megadrive/Master System configuration (8 pin circular din connector with RGB signals and mono audio). I have also removed the 5V regulator, since I want to power the system using a 5V power source.

I have already designed the PCB, but wanted to ask these questions before buying the parts.

Thanks in advance!
lightfoot256
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Re: Building my custom UZEBOX: Some newbie questions

Post by lightfoot256 »

doragasu wrote:I'm only interested in RGB output, so I'll remove the AD725 chip, and I'll output the video using the Sega Genesis/Megadrive/Master System configuration (8 pin circular din connector with RGB signals and mono audio)
Wow; didn't even realise this was possible; I'm guessing your using an original cable that converts the rgb to s-video? Surely it's not going to RF?? hehe. Would be interested in how you were planning on using this as I'd be interested in using this on my own version.

In regards to the other questions; Uze has a bunch of the connectors available that I think he can supply as cost+postage; And the 1284 never really took off due to issues overclocking; you also need to re-compile the binaries to work on the 1284 so I'd stick with the 644 if your after compatibility of games.

The others should be able to answer your remaining questions.
doragasu
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Re: Building my custom UZEBOX: Some newbie questions

Post by doragasu »

Thanks for help lightfoot256.

RGB format (15 kHz) is commonly supported by most TVs with SCART input in Europe (I think TVs in USA don't have this input, and I don't know if they have it or not in the rest of the world). To use RGB interface you just have to remove the AD725 chip and supporting circuitry, and wire the R, G, B, Audio, GND and PB0 (SYNC) signals to the SCART connector, like you can see in the SCART Interface by f0lken in the download page: http://belogic.com/uzebox/schematics/Uz ... feb-10.png.

Instead of the SCART cable, I'm using an 8 pin circular DIN connector, to use it with my Sega Megadrive/Genesis/Master System RGB cable.

RGB gives the best picture quality and is the simplest interface! And that is just because there is no modulation/demodulation involved in the process. No RF signals!
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uze6666
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Re: Building my custom UZEBOX: Some newbie questions

Post by uze6666 »

Hi Doragasu,

Indeed with european TVs no need for the AD725. Use the ATMega644 and not the ATmega644P or Atmega1284P, these ones have serious issues with overclocking. The 644 SMD should be fine since that's what was used on the AVCore. That said, I would buy more than one since Clay Cowgill (maker of the AVCore) reported that 3-5% could not be overclocked. So test and solder that part last!

I have a big reserve of brand new SNES connectors for the community. Send me a PM with the qty and your shipping address and I'll give you the final price.

-Uze
lightfoot256
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Re: Building my custom UZEBOX: Some newbie questions

Post by lightfoot256 »

doragasu wrote:Thanks for help lightfoot256.

RGB format (15 kHz) is commonly supported by most TVs with SCART input in Europe (I think TVs in USA don't have this input, and I don't know if they have it or not in the rest of the world). To use RGB interface you just have to remove the AD725 chip and supporting circuitry, and wire the R, G, B, Audio, GND and PB0 (SYNC) signals to the SCART connector, like you can see in the SCART Interface by f0lken in the download page: http://belogic.com/uzebox/schematics/Uz ... feb-10.png.

Instead of the SCART cable, I'm using an 8 pin circular DIN connector, to use it with my Sega Megadrive/Genesis/Master System RGB cable.

RGB gives the best picture quality and is the simplest interface! And that is just because there is no modulation/demodulation involved in the process. No RF signals!
Had a quick scan on google; I didn't even know you could get these cables or that the mega drive could even output RGB!! Nice. I'll have to order one and amend my own design; Wasn't looking forward to soldering a scart socket now I can use a tiny din socket :-D.
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