which kit to go with ?

Discuss general Uzebox topics here: features, wish list. nice to have, etc.
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mrpixels0
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which kit to go with ?

Post by mrpixels0 » Wed Aug 19, 2009 5:53 am

I was wondering what are the diffrences between the 2 available kits ?.

the one sold by clay cogwill the kit that is pre assembled looks great (odd place to put the sd-card reader though) but looks like a diffrent version of the ATmega644.

While the one sold by ladyada looks about the same but uses a diffrent variation of the ATmega644 and also comes pre programmed with some kind of bootloader ?.

now I know functionally they should be identical but something tells me that there might be subtle differences between the two, so I was wondering if I could get a response from folks who have one made by Mr. Cowgill. and also from ones who have the kit made by ladyada (sorry do not know her real name).

if there are any differences just list them as either pro or con and no I am not here to start a flame war just looking to make an informed choice is all.

thank you for time and I look forward to corresponding with the community.

Russ
Last edited by mrpixels0 on Wed Aug 19, 2009 7:28 am, edited 1 time in total.

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paul
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Re: which kit to go with ?

Post by paul » Wed Aug 19, 2009 6:30 am

hey Russ. Sorry, I can't help with your decision, but just wanted to say welcome aboard.

mrpixels0
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Re: which kit to go with ?

Post by mrpixels0 » Wed Aug 19, 2009 6:44 am

Thank You for the kind Welcome :)

Russ

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uze6666
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Re: which kit to go with ?

Post by uze6666 » Wed Aug 19, 2009 9:18 pm

Hey Russ,

Clay's kit (Avcore module+baseboard) and Ladyada's kit (Fuzebox) are both 100% functionally equivalent and compatible with my reference design. That is, code will run and produce the exact same result. The major difference is that the AVCore is a fully assembled, surface mount design while the Fuzebox is a built-it-yourself kit. The Avcore is basically a full Uzebox on a 40-pins chip size module. It can be plugged in any project that would require an MCU and video and/or sound.

Here's some differences:
  • They both use the same Atmega644 (but in different package) and the same weighted DAC design.
  • For the RGB-to-NTSC conversion, the AVcore uses an AD723 vs. an AD725 for the Fuzebox. Although these two chips produces the exact same results, Clay preferred the AD723 because it's newer and does not require big 220uf capacitor (essential for his small module design).
  • The SD card interface is, again, 100% compatible, the AVCore uses MicroSD (again to fit on the small module) while the Fuzebox uses the regular size.
  • Both have S-VIDEO output. The AVCore implements the "Luma Trap" on the AD723 not the Fuzebox. This circuit gives less artifact and somewhat better colors on the composite video output (no difference on the S-VIDEO output).
  • Both also adds to my design: A pin to control the external LED, a pin to read the "soft power" switch and a pin to turn on/off the AD725/AD723.
  • The AVCore come with a single 6-pins SPI programming port, meaning you must have/buy an ISP programmer (~35$). The Fuzebox have 6 & 10 pins SPI programming ports & also an FTDI serial programming port. It ships with a cable to use the FTDI port and the mega644 pre-flashed with a 2K bootloader (required to use the FTDI).
  • Assembled vs DIY: If you know nothing about electronics and just want the thing to work, get the AVcore. If you want to build it yourself without to much hassle, get the Fuzebox. If you want to do everything yourself, build the reference design.
On the pro and cons side, all I could say is that the Avcore has the Luma trap but you can not replace the ATMega644. The Fuzebox allows you to replace the ATMega644 and you can also program the chip without having to buy an ISP programmer (note this has it's issues, read the bootloader thread for more).

I've heard the sound output is a bit louder on the Fuzebox that the AVCore. Also, I find the video quality is a bit better on the AVCore. Clay Cowgill is an electronics engineer who has been working in the field for many year (even designing video games boards!), so that may explain things. At the same time I really enjoyed building Ladyada's kit, so it's a tie for me. :)

Hope that helps,

-Uze

ps: I added this to the FAQ.

mrpixels0
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Re: which kit to go with ?

Post by mrpixels0 » Wed Aug 19, 2009 10:49 pm

Thank you Mr. Uze

That was very helpful and comprehensive breakdown, based on that alone I will have to go with Mr. Cowgills design as it affords me less difficulty with changing out the boot loader which uses less space than the other kit option. (been reading some other posts after work this morning.).

Again thank you for the response.

Russ

tim1724
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Re: which kit to go with ?

Post by tim1724 » Thu Aug 20, 2009 7:48 pm

It's pretty trivial to disable and overwrite the bootloader on the fuzebox. (just change the fuses, then program it with an ISP programmer.)

fuzebox may be upgradable to an ATmega1284 at some point in the future, if they ever ship the damn things (and if they can be overclocked reliably)

mrpixels0
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Re: which kit to go with ?

Post by mrpixels0 » Thu Aug 20, 2009 9:02 pm

Hi Tim,

Did not know you could overwrite it without ruining it, yeah I was reading some about that on the forums earlier sounds as if it would be a great step up in the long run if it can be made to work, as I am just learning C and the way the graphics works on this version of the chip I hope a new chip will be the same as this one from the use of the kernel API stand point.

How much would a ATmega1284 add to the cost of a new board and chip together would it be the same or higher ?, also if one already had a board and just wanted to upgrade the ATmega644 to 1284 would the base board you already have work or would it need modifications to make it work ?.

Russ

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uze6666
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Re: which kit to go with ?

Post by uze6666 » Thu Aug 20, 2009 11:11 pm

How much would a ATmega1284 add to the cost of a new board and chip together would it be the same or higher ?, also if one already had a board and just wanted to upgrade the ATmega644 to 1284 would the base board you already have work or would it need modifications to make it work ?.
They're about the same price (~7$USD). It's a simple replacement with the Fuzebox since the chip is actually mounted into a socket. On the AVCore it can't be replaced by hand (for the common mortals out there). If Clay Cowgill ever makes a 1284p version, it will work with teh same baseboard.

As for the code goes, due to extended memory, some jump & call instructions takes 1 more cycle. That *could* introduce jitter in the picture. The kernel would have to be tweaked to not use these instruction in time critical areas.

Btw, the bootloader thing is simply a zone in the upper program flash memory (ie, >60k) that the MCU starts executing code from (instead of 0x0000). It configurable by programing some fuses. I was mentioning this in my earlier post because almost all have bough the Fuzebox with the FTDI cable only. And without an ISP programmer it's very tricky to reflash the bootloader region.

-Uze

mrpixels0
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Joined: Mon Aug 17, 2009 8:08 am

Re: which kit to go with ?

Post by mrpixels0 » Fri Aug 21, 2009 5:55 am

Hello Mr. uze

so if I bought a Fusebox and an SPI programmer I could just remove the boot loader and just flash any game rom and run it ?, if that is the case then I will buy an avcore and a fusebox then because one comes with a nice little case to put it in :).

thanks for helping me understand it all better :), can't wait till payday which is also the same day as bonus checks for this quarter yaaaaa.

Russ

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