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M3iZero-GMPZ003.md

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M3i Zero GMP-Z003

Not to be mistaken with the M3i Zero non GMP-Z003 model, this card is very different from it's predecessor.

Hardware

Image of the carts PCB Image of the FPGA

Flash Memory

The GMP-Z003 uses a MX29LV160DBXEI-70G for flash memory, it is a 2MB chip. This device operates over a voltage range of 2.7V to 3.6V typically using a 3V power supply input. The flash memory is read directly to the NDS as a cartridge, the format of which can be found here. It is writeable through the flashing process.

Flashing

The device can be flashed by providing DC power to the J3 port. I just stripped a USB cable and put the positive and ground in. The FPGA searches the SD card for /F_CORE.DAT and copies 0x200000 -> 0x400000 to the flash memory chip. I believe the F_CORE.DAT needs to be signed in order for the FPGA to copy it first however.

The LED light D1 will change depending on the status of the flash:

  • Nothing: No power or completed
  • Static: Error reading F_CORE.DAT (SD card might not be inserted, etc..)
  • Flashing: Copying F_CORE.DAT to the flash memory.

Alternatively the device can be flashed whilst inserted via the DS itself using card commands.

Card Commands

The reconstructed C source of that DLDI interface can be found here: iointerface.c

  • B0 00 00 00 00 00 00 00 = Card Info (should be 0x5AA5)
  • C9 oo oo oo oo xx 00 00 = Read (FIFO read 0x200 words)
  • C5 oo oo oo oo xx 00 00 = Write (write 0x200 words)
  • C6 00 00 00 00 00 00 00 = get write status, read 1 word (= 0 when finished)
  • CA 00 00 00 00 00 00 00 = get read status, read 1 word (= 0 when finished)

Where oooooo is the offset in number of words(?), MSB first Where xx represents the type in the DLDI interface this is set to 0x00 for SD card access.

  • 0x00 : SD card access afaik.
  • 0xE0: "SW" header, used with offset = 0, after that offset += 0x10000 (in number of words)
  • 0xF0: "SW" regular sector (0x200 bytes)
  • 0xA0: "HW" sector. One sector (header ?) is at 0x80000000 then the others start at offset 0.

Credits

  • TuxSH for help identifying the cart commands.