Hi Folks,

I'm currently working on a SEGA GameGear Flash cart. I had been making several post under the discussion topic
"Do it yourself Gameboy Flashcart" but a group of us were doing allot of discussing and I figured it deserves it's own topic page.
So I will re-post a few of the images and key points to give you all a quick recap on this crazy endeavor that I've been working on.

To start:

The real issue here is verification of the actual pinout connection for the Stock issued ROM chips that are used in the actual Sega GG carts.
There are allot of different pinout diagrams around on the net, so it's hard to confirm as to the actual connections without any legit schematics
or Datasheets available. I think that is why there are very few DIY GG Flash carts around.

Shown below is one of the Pinout Diagrams I found online:




Below is the Cart scan of a standard Sega GAMEGEAR cart.


Many of us Backtrack the PCB trace lines using a standard GG cartridge along with these diagrams and then devise a possible
ROM Pinout scheme for the ROM contacts on the PCB. Yet, these connections are all based on the "Hobbyist" provided Cart Edge diagrams
which are questionable as to their accuracy.

I still have some issues with my GameGear? Flash cart but I'm not giving up.

Here is my Current Mess of Wires and Solder! UUGGgghhhhhrrrr!!


In the photo of my current cart (seen above) you can see the Red wires connected to pins 41 & 42 of the cart edge. These I have connected
to a jumper on the outside of the cartridge enclosure. When these two contacts are bridged or unbridged determines if the GameGear is in
a SMS or GameGear mode. There are a few Cartridge adapters for the GG that allow you to use SMS cartridges. So one could also use this
flash cart to play SMS Roms. All the more motivation to get this puppy running

****Still under testing****** Here is my latest updated "GameGear ROM Pinout & Cart Edge Connections Diagram" that I've come up with
and this is what I'm working on and still trying to get working. So by all means if you can see any errors or misshaps I'd love to trade research
with others working on similar Projects.





I look forward to hearing your replies,

Regards,
-Gerry

Once the dimensions have been verified, (and a single EEPROM cart is working) a SMS ROM loading cart can be designed.

Has using an OR gate on the enable input been tried yet?

The DIY SMS cartridges used this logic

• !CEchip=(!CEedge OR !M0-7edge)
• !OEchip=!RDedge
• !WE=!WR AND SW

• http://www.smspower.org/Development/SMSReader-Overview#x32kCartridgesNotPaged
• http://www.smspower.org/Development/SMSReader-32KCartridge

edit:grammar.

Yeah I did actually try that already and didn't have any luck.

I'm hooking up the Original ROM to my Logic Analyzer hopefully sometime tomorrow.
I might be able to find something from the readings I collect......well hopefully.

I'll see how it goes.
-Gerry

Hey Snow_Cat,

Can you Rig up a generic TQFP 44 Pin LBR file for me? You seem to have quite the Nack using Eagle. More so than I do.
No designations needed for the pins at this point. I wasn't able to find one on the Eagle website.
If possible have the first Bottom pin on the left designated as Pin 1. The Flat Edge corner can be on the Bottom Right side.
Like this Image below:



I found a TQFP44 LBR but it was for a specific Micro-controller and the Designations for the pins in the Schematic editor will not be the same for the version
I'll be using this for. So this is why I wanted a Generic one with no pin designations.

I'm trying to test something out in Eagle for one of the GG Carts.

Ohh! and your Cartridge Edge connections you made in Eagle are perfect!
I printed one off and it matches the cart Edge TABs perfectly.
Nice Job on that one!


If it's a huge Job to make this LBR file, don't worry about it.
I'll just have to sit down with some of the Tutorials and figure out how to use the Eagle software a little more.

Talk to you later,
-Gerry

Not a problem; I should be able to finish after lunch tommorow.

However, so that you have to check my ZIP-45, I will be cranking this up to 11, maybe 12.

Just print it on plain paper with no scaling (B&W is best and cheapest) and take a picture of it next to the cart, and a ruler if possible.
edit: W/pics! (pics or it didn't happen)

2010.09.27.zip
Eagle library has a lovely bunch of 44 pin chips
Didn't have enough time to finish BGA,PGA,IF,CardEdge,0.07",0.3",0.9" and other uncommon variants.
You want QFP44S BTW.

Hey Snow_Cat,

That's really great. I appreciate the work you've done here.

I've been really busy over the past week helping my Family out as they are selling their house. So lots of things have taken priority to the Fun in the Lab with Sega circuits.
As for your Eagle cart Edge design...I printed the sheet off and lined the paper up with a real cartridge and it is a perfect match. I've already made a transparency sheet for etching using your design.

Now, I have also made some new discoveries through SMSpower and a few of the key people there.

The Sega ROM chips are apparently a custom chip with Memory Mapping integration. So it doesn't function like a regular ROM chip at all which sucks.
However, there is speculation that the 1Mbyte GG carts like "Garfield" may be an exception as they have the 315-5912 Memory Bank controller chip in the mix.
The link below is to my Topic postings on SMSpower:
http://www.smspower.org/forums/viewtopic.php?t=12604

In any case, just yesterday I got my Logic Analyzer up and running and I'm still performing some scans on Various ROMs. I'm trying to find some similarities in the Field patterns of the Sega chips and hopefully find the correct Pin assignments for interfacing to a generic Flash Chip.




Notice above here I used an old Genesis cart to house the Extension PCB connector for the Interface clips. Sweet!






Hopefully I'll have some time to play in the lab Tomorrow.

Talk to you later,
-Gerry

This sounds consistent with what I've heard of GameGear cartridges.
It would also explain the presence of the 315-5235 paging chip on the 1M-or-256k dev. cart. (chip described in earlier post)

Yeah true..... it makes sense.

Have you ever checked out Tototek's carts? it looks like he does allot of his Memory mapping/paging with CPLD's & FPGA's or other Microcontroller's.
There was one version of a Gameboy Flash cart I found off Reiner Ziegler's site, that used a CPLD to emulate the Memory Bank controller (MBC5).
It was pretty sweet.

This one here:
http://home1.stofanet.dk/hvaba/gameboy/mbc5cpld/cpldcart.html


-Gerry

Yes I have; though that specific example is one that I've not seen before.
I did read that the CPLD used in their Gamegear cart was rather power hungry though I suspect that the 9500x is a bit more than is needed to implement a cart, however I haven't done the research to see if using descrete IC's could be any more efficient (power wise).

Hey Snow_Cat,
I got a 512Kb version up and running!!

http://www.smspower.org/forums/files/gg_cart_final_060_425.jpg

http://www.smspower.org/forums/files/gg_cart_final_053_756.jpg

http://www.smspower.org/forums/files/gg_fc_complete_625.jpg

http://www.smspower.org/forums/files/gg_flash_cart_pcb_a002_678.jpg

http://www.smspower.org/forums/files/gg_flash_cart_pcb_a003_149.jpg

I used your Eagle library designs for the SEGA Components, and I got a working 512Kb version up and running.
The 315-5235 SMS mapper was the key. Frekin SEGA with their integrated mapping. HA!

Check out the details on my Website.
I have a 5 part instructional video made along with a 26 page PDF download including the schematic and my Prototype PCB layout.

FANTASTIC!! now we must continue to work on the 1 Megabyte version.

Here is the link to my Website:
http://www.digital-circuitry.com/GameGear.htm

Talk to you soon,
-Gerry

Hi Snow_Cat,

You should Register and jump in on the Topic I have opened on SMSPower for this 512Kb design.
Charles MacDonald was interested in the Specs for the Mapper chip layout you put together for the Eagle Library.

Anyhow,
here is the link to the thread.

http://www.smspower.org/forums/viewtopic.php?t=12734

You should jump in as I'm sure other members will have other questions.


TTYL
-Gerry

Hey, sorry about that - I've been busy and missed the completion of that build.

I'll register there some time this month. And would like a link back to my site at meow-snow.blogspot.com --
I'll add this to the growing list of subjects I need to post about.

Did you need me to reproduce the traces from the original 1 MB SEGA devcart, or would using descrete logic be preferable to hunting for the specific mapper chip.

Hey Snow_Cat,

No worries, we are all so busy with things.

I just added a link to your webpage on my website.
http://www.digital-circuitry.com/GameGear.htm

Well, if there are detailed enough photos for you to backtrace them that could help, but allot of the time
so many of the traces are covered up by the Chips, which makes it impossible to determine all the pin connections.

Designing our own Mapper would be really awesome.
Do you have any ideas how to go about this? I had thought of doing this and then implementing the design to a CPLD.
I'm still learning CPLD & FPGA implementation along with VHDL code so, I'm not at the point to tackle a custom mapper chip just yet.
Do you have any ideas on designing one using discreet logic?

Too bad the SEGA Datasheets for the Mappers aren't available.

I'm still working on possibly using the 315-5912 SEGA mapper.
Possibly some form of implementing a 1 Megabyte Flash chip.

School is keeping me busy though, so I'm not sure when I will find the time to continue working on this.

Anyhow Snow_Cat,
I'll talk to you later.
-Gerry