Custom MBC5 cartridge with Xilinx CPLD, 512kB flash and 128kB SRAM
|Introduction||What the cart contains, and a picture of the cart hooked to a gameboy.|
|Partslist||The cpld, the memories and a little extra|
|Cart Schematic||Not much to see, the cpld pretty much do all the interesting stuff|
|Cart PCB||Near eurocard size, "single" sided.|
|Link PCB||Just a extender pcb fitting in to the gameboy cartridge slot|
|Downloads||Why did I ever start with these stupid explanations...|
|Index page||Main index page.|
|Links & Credits||Located on other page|
The use of the word cartridge is a little
far fetched, as the pcb is bigger than the gameboy plus the fact
that it doesn't even fit in the expansion slot, but uses a ribbon cable with a passive link PCB to connect
to the gameboy. Next step could be to minimize it, but that would require a through-plated pcb.
Digital part consists
of a Xilinx CPLD whichs hosts the MBC5 functionality and i/o, a 512 kBytes
flash and a
128 kBytes sram.
IDC interfaces besides
JTAG and a 5V connector :
Cart connector IDC1 IDC2 To gameboy cartridge slot via link PCB. Karlsruhe/Marc Rawer pinout.
IO connector IDC3 IDC4 All i/o pins from the CPLD including i/0 select and relevant adress signals.
Emulator IDC5 Matches at least Andrew March's "emul8r".
All IDC connectors are 34 pins to ensure that even the smallest distraction will have fatal consequences.
The cart have a fixed 5V regulator intended to drive the cpldcart and a adjustable regulator set to 3V for the gameboy.
In this scenario the current consumption is close to 200mA. The pocket gameboy uses approx.80mA (at 3V, no sleep)
and the cpldcart approx. 100 mA.
Note that the maximum input voltage is about 12V unless the regulators is fitted with some kind of heatsink.
The external power supply is connected via
a 4 pin molex and a single pin supplies 3V to the gameboy. There is
no 5V connection from the cpldcart into the gameboy (via the link cable) but no harm is done if it should happen. (!)
The 3V must be supplied in order for the smps in the gameboy to produce the negative bias voltage for the LCD.
It would be nice to have the opportunity to
be able to run both the gameboy and the mbc5/cpld cart on the normal
gameboy batteries alone (for a short time....), but i haven't done anything to check it out yet.
How to build :
Like anything else.
I have no idea what it costs to produce a cartridge as the one shown here. And i don't care :-) This is completely
besides the point with this project. If you think that this could be a cheap alternative to a whatever consumer pirate
copier that might exist then I am afraid I will have to dissapoint you right away. Sorry !
5 IDC34 (17x2 connectors). At least the one for the link cable are mandatory.
7 pin molex JTAG programming jig.
4 pin molex DC IN, external 200mA DC power supply.
1 pin molex GB 3V, to GB battery terminal or DC input plug.
100nF & 47uF decoupling caps + a few resistors and a LM317 + 7805.
|CART - SCHEMATIC|
See downloads for a postscript version of the schematic.
These contains the three 8bit CPLD i/o ports PORTA, PORTB and PORTC. The definition of these ports are discussed on cpld page. The signals IO_CE and A0..A3 are included so that the free i/o adresses can be used as well. Note that there is no read or write control signals available on the connector.
|CART - PCB|
Two sided PCB intended to be made as single side PCB with wire links (i.e. enameled wire) instead of copper tracks in upper layer.
Dimension : 160 x 80 mm
|LINK - PCB|
The 5V track is by default open to let the gameboy supply its own internal 5V circuits.
The dimensions are 51.3 mm X 90.4 mm but the
essential measure is 47.0 mm between the centers of the outermost gameboy
(the pin spacing is 1.5 mm nominal).
One way to position the link PCB in the gameboy cartridge slot is to murder a cartridge and use the plastic shells. In this case
the PCB should be 0.8 mm thick. You'll have to cut away the 'end-piece' in the plastic shells to make it fit.
Zip'ed postscript printer file (HP5) with
the cart schematic
Testprogram written in GBDK, both binary and source. This is the program that runs on the gameboy
in the photo above. Can run in no$ emulator as well (except for the obvious exeptions!)
|CART - LINKS & CREDITS|
& Credits located on other page...
Made with Netscape Composer.
Basic font is Arial Narrow.
Copyright Claus Bjerre Pedersen 1999