N64 flash board

hi,
a friend of mine has one of this. this board will soon be mine. I know you can program it with a gang writer, but i want to know if someone knows a way to program this cart without a gang writer. a schematic or something will be verry useful.
thanx

 

There you have a nice project for your christmas holidays .
I have a flash cart also, but i dont think it will be easy to reverse.

 

I'm sure it's EXTREMELY easy to reverse if you can build a DIY cart reader that can simply read and write to the cart. This isn't a project for newbies though since you'll have to design/build your own cart interface.

Probably the ASIC is only there to interface the flash to the cart bus, and decode ROM/SRAM so the only thing you have to think about is writing the cartridge.

This is easy because there's either a "cart writable?" register that unlocks /WE so the gang writer can program the cart or there's nothing at all. If there is a register to unlock /WE and you don't know how to figure it out, you can cut the track from the ASIC to /WE and jumper /WR from the cartridge connector directly to the Flash chips. Once you can write to the Flash, you only need to read the datasheet to find the programming algorithm that brand uses.

 

I'd have a look at the design of the flash cart itself - are the flash ROMs managed by an ASIC, or do they share the data bus and trigger on high address bits?

It's possible to do by yourself. It will depend on how much experience you have with digitial electronics.

I can explain to you how the n64 PI bus works (cartridge interface). The timing is fairly simple, though the address/data lines are multiplexed.

The hardest part is figuring out the scheme the cart used to write directly to the flash ROMs. Ideally, you would borrow a flash gang writer, and put a logic analyzer on the cart bus. But you just have to think and use what you have.

 

thax for your replyes. i don't have experience to design such a device to dump or write a flash board or a n64 cart. but if someone has a schematic of this device i can build it.
this flash board has the game 40 winks on it. i will have it next week i think.
See the pictures.

 

Even if he knows absolutely _nothing_ of electronics?

 

I don't think there's a free design on the internet and I'm not so sure that someone would share one since it can effectively be used as a "linker" in a commercial project. Also the device would require more wires than is sensible to use without a PCB and PCBs are expensive and time consuming to get. I also guarantee you'll need electronics skills to troubleshoot the thing once it's built, nothing ever works the first time even if you're positive it's supposed to.

Besides, without a doubt it will cost you less time, energy, money (yes even money!) and frustration to just buy a Gang Writer. A couple years ago I remember them selling for ~$100!

Of course not, but he asked to build it

 

I have experience with soldering and with PCBs. I worked with smd electronics. I've replaced the rom in a gameboy color cart with am29f032 TSOP40. i also made a programmer on PCB for this cart based on atmega8515, and with usb connection through ft232bl. but it wasn't my design. what i'm trying to say is that if someone can help with the schematics, i can build it. thanx again

 

Can you program? If so, I can whip up an unguaranteed-extremely-cheap circuit that should do what you need but it will probably take *forever* to read/program a cartridge.

 

sorry, i can't program.

 

xD There you go. Im offering myself to do that! You need me?

 

YES!!! Plese help me. i don't care if will take an hour to program it. i live in romania so i'm realy lucky i found suck a cart and i'm sure i will never find a gang writer. any help is very appreciated.

 

Calpis? marshall?

 

This is the simplest / cheapest design I could think of. The chips together should cost under US$8 and after that you only need a 3V power supply circuit and N64 connector.
It's very slow for writing and it's *HELLA* slow for reading (since you'll need to change the port's direction to write the register to toggle /RD). You can however speed up reading to much faster than writing by putting /RD on the last parallel port control line instead of the register.

Make sure it's made with 74HCXXX chips, NOT 74HCT! The chips need to run off 3V. You also need to connect all parallel port GNDs to this device's GND. You may need to put pull-up resistors on all the parallel port lines too depending on your port. You can also replace the 74245 with the 74244 to save some money too.

Edit: Bad schematic!

 

calpis, thanx for the schematic. tomorrow i will go to buy the parts. but the last time i searched for 74hc374 i only found 74HCT374. maybe tomorrow i'll have better luck. but if i can't find 74hc can i use 74hct with a power supply of 5v to the ic's and 3v to the cart?

 

Wait! I see a very stupid error in it, the last circuit won't even work. I'll do a better one which is much faster and even more compatible with different parallel ports too.
I changed the latches to 74HC574, they're the same as 74374 but have a different pinout, they should be easier to find.

You could do damage to the cart. I don't think it will, but it could.



Kammedo:

Use this if you need it: http://www.beyondlogic.org/spp/parallel.htm
You'll need this DLL if you want to use this in Win XP:
http://logix4u.net/Legacy_Ports/Parallel_Port/Inpout32.dll_for_Windows_98/2000/NT/XP.html

Don't forget that the outputs/inputs of the parallel port can be inverted.
Make sure you allow only ONE 244 input at a time! They're acting as a poorman's MUX.
The registers are loaded on the rising edge of CLK.
Make sure you disable U3 and U4's output before you intend to read the bus!

To access the cart:
1) make everything inactive
2) put most significant byte of address on data port (378), clk U3
3) put next to most sig byte of address on data port, clk U4
4) put xxxx1xxx onto data, clk U1 (to assert ALEH)
5) do steps 2-4 but use least significant bytes and ALEL
If you want to read: assert /RD and choose which nibble to read with U2. Read them all in, de-assert /RD, re-assert it to get the next word etc. (thanks to N64's "burst mode")
If you want to write: put data into U3 and U4, then assert /WR.
De-assert it, put more data into U3 and U4, re-assert /WR etc etc .

Easy!

 

That's a pretty neat circuit. The first cart dumper I made was a pic16lf877 running at 3.3v hooked straight to the cart pins and a max3233 level converter. It was danged slow.

The next couple of days I ought to have some decent free time. If I can find the right 74 chips I'll see if I can put something together.

Really reminds me of the flash cart designed by Valeriya pudov a long time ago. I came very close to actually building it

 

@ Calpis
Thanx for the new schematic
no luck with th HC chips. at the local store they have only HCT and LS. but i found an on-line suplier in romania so i ordered all the necesary stuff. i already have the cart connector and the IC's i think will arrive in 4 or 5 days.

@marshallh
I've seen your schematic at benhack. but you said there the dump was bad and the pic was slow.

 

Noted. Will see to do something when i get some spare time.

 

Hi,
today i recived the flash board and the IC parts.
but there's a problem. they send me only 3 x 74hc574 and they told they don't have the fourth 74hc574 in stock, but in about a week or two they will send it to me. meanwhile i started designing the PCB. it's almost complete. But i have some questions. Where should i connect pin 11 (SELECT) from U3 and pin 11 (INIT) from U4?
and please tell me if i did this right:
/RESET--->/COLD_RESET (pin 20 from n64 cart)
ALEH--->ALEL_H (pin 35 from n64 cart)
ALEL--->ALE_L (pin 33 from n64 cart)
thanx
and for the power supply i'm gonna use the n64 power suplly (3.3v)