Simplified script for one-time programming of a N64 EEPROM

[weleusernamegod]

Hello everyone!

Ever since my N64 Mario Party savegame got corrupted, I have been in search of a solution to restore it. It was pretty much a 100% savegame with all of the mini-games unlocked, which was great for having friends over :(

My guess is that either the EEPROM got randomly corrupt, or the savegame got lost over time. After desoldering the chip (BK4D-NUS, I also have a BU9850 from a donor cartridge) I tried to read it with my programmer, but to no avail - I later found out that Nintendo used a proprietary method to talk to the EEPROM. This is what led me to the open source cartreader.

My plan is to 'write' (more like copy and adapt) a simplified script that is a sort of 'one-shot programmer' that it only programs the chip with a binary file of a 100% savegame. I have several Arduinos (Uno, Nano and Mega), an Adafruit clock generator and various breadboard equipment.

So now my question: is it possible to do this with my equipment and somewhat limited knowledge (I'm only a hobbyist)? I might build a cartreader at some point in the future, but for this first project I thought it would be a bit overkill :) I'd love to hear from anyone interested in helping out with this!

Yves

PS: This is the part of the cardreader's code responsible for writing to and reading from the N64's EEPROM, so this might be the section I'm looking for:

    // Write Eeprom to cartridge
    void writeEeprom() {

    // Create filepath
    sprintf(filePath, "%s/%s", filePath, fileName);
    println_Msg(F("Writing..."));
    println_Msg(filePath);
    display_Update();

    // Open file on sd card
    if (myFile.open(filePath, O_READ)) {
      // 2 command bytes and 8 data bytes
      byte command[2 + 8];
      command[0] = 0x05;

      // Note: eepPages can be 256, so page must be able to get to 256 for the
      // loop to exit. So it is not possible to use command[1] directly as loop
      // counter.
      for (int page = 0; page < eepPages; page++) {
        command[1] = page;
        // TODO: read 512 bytes in a 512 + 2 bytes buffer, and move the command start 32 bytes at a time
        myFile.read(command + 2, sizeof(command) - 2);
        // Disable interrupts for more uniform clock pulses

        // Blink led
        blinkLED();
        if (page)
          delay(50);  // Wait 50ms between pages when writing

        noInterrupts();
        sendJoyBus(command, sizeof(command));
        interrupts();
      }
    }

[sanni]

Sure.

To convert save to array: https://notisrac.github.io/FileToCArray/

I only had a 16K eeprom to test though. Save in example is for Perfect Dark, last 8 bytes don't get written, not sure if bug in the code or eeprom broken.

/**
 * Gamecube controller to Nintendo 64 adapter by Andrew Brown
 * Rewritten for N64 to HID by Peter Den Hartog
 * Rewritten for N64 Eeprom by sanni
 */

/******************************************
  Defines
 *****************************************/
// these two macros set arduino pin 2 to input or output, which with an
// external 1K pull-up resistor to the 3.3V rail, is like pulling it high or
// low.  These operations translate to 1 op code, which takes 2 cycles
#define N64_HIGH DDRD &= ~0x04
#define N64_LOW DDRD |= 0x04
#define N64_QUERY (PIND & 0x04)

/******************************************
   Variables
 *****************************************/
// Received N64 Eeprom data bits, 1 page
bool tempBits[65];
byte eepBuffer[512];

// 4K eeprom
//int eepPages = 64;

// 16K eeprom
int eepPages = 256;

const PROGMEM byte eepSave[] = {
  0x83, 0x79, 0xe7, 0xab, 0xff, 0xff, 0xff, 0xff, 0x08, 0x05, 0xb0, 0x70, 0xd5, 0xd0, 0xc9, 0x7a,
  0x4d, 0xab, 0xa0, 0x29, 0x32, 0xb2, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x2c, 0xb2, 0xb6,
  0x36, 0x37, 0xbb, 0x80, 0x00, 0x00, 0x00, 0x21, 0x36, 0x3a, 0xb2, 0x80, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x26, 0xb0, 0xb3, 0xb2, 0xb7, 0x3a, 0x30, 0x80, 0x00, 0x00, 0x21, 0xbc, 0xb0, 0xb7, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x27, 0xb9, 0x30, 0xb7, 0x33, 0xb2, 0x80, 0x00, 0x00, 0x00, 0x28,
  0x34, 0xb7, 0x35, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x21, 0x39, 0x37, 0xbb, 0xb7, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x7f, 0xc4, 0xfe, 0xee, 0xaa, 0xbe, 0xff, 0xf0, 0x4d, 0xab, 0xa0, 0x29, 0x32,
  0x32, 0x39, 0x70, 0x58, 0xbf, 0xbc, 0xbb, 0x81, 0x08, 0x05, 0xb0, 0x70, 0xd5, 0xd0, 0xa9, 0x86,
  0x5b, 0xab, 0xa0, 0x29, 0x32, 0xb2, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x2c, 0xb2, 0xb6,
  0x36, 0x37, 0xbb, 0x80, 0x00, 0x00, 0x00, 0x21, 0x36, 0x3a, 0xb2, 0x80, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x26, 0xb0, 0xb3, 0xb2, 0xb7, 0x3a, 0x30, 0x80, 0x00, 0x00, 0x21, 0xbc, 0xb0, 0xb7, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x27, 0xb9, 0x30, 0xb7, 0x33, 0xb2, 0x80, 0x00, 0x00, 0x00, 0x28,
  0x34, 0xb7, 0x35, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x21, 0x39, 0x37, 0xbb, 0xb7, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x7f, 0xc4, 0xfe, 0xee, 0xaa, 0xbe, 0xff, 0xf0, 0x5b, 0xab, 0xa0, 0x29, 0x32,
  0x35, 0xcc, 0xac, 0xa0, 0x51, 0xb4, 0xe7, 0x06, 0x10, 0x04, 0xe0, 0x60, 0xd5, 0xd1, 0x0d, 0xf6,
  0x44, 0x61, 0x72, 0x6b, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x13, 0x3f, 0xb1, 0xc4, 0x00,
  0x00, 0x00, 0x34, 0x03, 0x08, 0xc0, 0x0e, 0x00, 0x00, 0x65, 0x00, 0x0a, 0x00, 0x00, 0x32, 0x00,
  0x09, 0xcf, 0x55, 0x00, 0x07, 0x09, 0x60, 0x00, 0x90, 0x20, 0x02, 0x29, 0xc0, 0x00, 0xda, 0x73,
  0x00, 0x01, 0xc0, 0x02, 0xb0, 0x02, 0x14, 0x01, 0x70, 0x32, 0xee, 0xee, 0xee, 0xee, 0xee, 0xee,
  0x8e, 0xc8, 0xcc, 0x88, 0x88, 0x88, 0x88, 0x80, 0x00, 0x07, 0x10, 0x82, 0x60, 0x10, 0x44, 0x61,
  0x73, 0xbb, 0x99, 0x88, 0xff, 0xff, 0xff, 0xff, 0x10, 0x04, 0xe0, 0x60, 0xd5, 0xd2, 0xed, 0xea,
  0x44, 0x61, 0x72, 0x6b, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x13, 0x38, 0x61, 0xc4, 0x00,
  0x00, 0x00, 0x34, 0x03, 0x08, 0x80, 0x0d, 0xf8, 0x00, 0x64, 0x80, 0x0a, 0x00, 0x00, 0x32, 0x00,
  0x09, 0xcc, 0x52, 0x80, 0x07, 0x08, 0x30, 0x00, 0x8f, 0xd0, 0x02, 0x29, 0xc0, 0x00, 0xda, 0x47,
  0x00, 0x01, 0xc0, 0x02, 0xb0, 0x02, 0x14, 0x01, 0x70, 0x32, 0xee, 0xee, 0xee, 0xee, 0xee, 0xee,
  0x8e, 0xc8, 0xcc, 0x88, 0x88, 0x88, 0x88, 0x80, 0x00, 0x07, 0x10, 0x82, 0x60, 0x10, 0x44, 0x61,
  0xca, 0x68, 0x99, 0x33, 0x1d, 0xf1, 0x88, 0xe4, 0x10, 0x04, 0xe0, 0x60, 0xd5, 0xd1, 0x24, 0xc6,
  0x45, 0x61, 0x73, 0x74, 0x6f, 0x6e, 0x00, 0x00, 0x00, 0x00, 0x00, 0x07, 0xc8, 0x91, 0x28, 0xc0,
  0x00, 0x00, 0x34, 0x00, 0xa5, 0x00, 0x06, 0xfc, 0x00, 0x20, 0x80, 0x01, 0xf0, 0x00, 0x1c, 0x00,
  0x03, 0x65, 0x3d, 0x40, 0x01, 0x93, 0xa0, 0x00, 0x46, 0xdc, 0x00, 0x43, 0xc0, 0x00, 0x32, 0x50,
  0x00, 0x01, 0xc0, 0x00, 0xc0, 0x00, 0x24, 0x00, 0x3c, 0x7e, 0xe2, 0x22, 0x22, 0x22, 0x26, 0x66,
  0x06, 0x40, 0x44, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x07, 0x10, 0x02, 0x40, 0x20, 0x45, 0x61,
  0x2f, 0x46, 0x00, 0x88, 0x18, 0x89, 0xc2, 0x4e, 0x10, 0x04, 0xe0, 0x60, 0xd5, 0xd1, 0x41, 0x96,
  0x6a, 0x61, 0x6b, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0x7d, 0x11, 0xa4, 0x00,
  0x00, 0x00, 0x34, 0x00, 0x12, 0x80, 0x01, 0xe8, 0x00, 0x0a, 0x00, 0x00, 0xc0, 0x00, 0x0e, 0x00,
  0x00, 0xed, 0x19, 0x80, 0x00, 0x30, 0x70, 0x00, 0x13, 0x30, 0x00, 0x0c, 0xc0, 0x00, 0x15, 0x04,
  0x00, 0x00, 0x00, 0x00, 0x20, 0x00, 0x00, 0x00, 0x10, 0x7e, 0xe2, 0x22, 0x22, 0x22, 0x22, 0x22,
  0x02, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x20, 0x02, 0xa0, 0x6a, 0x61,
  0x8e, 0xe8, 0xdc, 0x30, 0x50, 0xf7, 0x78, 0x01, 0x10, 0x04, 0xe0, 0x60, 0xd5, 0xd1, 0x60, 0x3e,
  0x76, 0x61, 0x6e, 0x79, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x5f, 0x40, 0x62, 0x40,
  0x00, 0x00, 0x30, 0x00, 0x09, 0xc0, 0x00, 0x68, 0x00, 0x01, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x2d, 0x3e, 0x80, 0x00, 0x18, 0x20, 0x00, 0x04, 0x0c, 0x00, 0x07, 0x80, 0x00, 0x05, 0x66,
  0x00, 0x00, 0x00, 0x00, 0x10, 0x00, 0x00, 0x00, 0x00, 0x7e, 0xe0, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x10, 0x00, 0x00, 0x20, 0x76, 0x61,
  0x55, 0x90, 0xf0, 0x52, 0xff, 0xff, 0xff, 0xff, 0x20, 0x03, 0x10, 0x50, 0xd5, 0xd1, 0x80, 0x12,
  0x6a, 0x6f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xe0, 0x03, 0xff, 0xc0, 0x00,
  0xc0, 0x00, 0x00, 0x60, 0x00, 0x00, 0x30, 0x00, 0x00, 0x18, 0x00, 0x00, 0x0c, 0x00, 0x00, 0x06,
  0x00, 0x00, 0x03, 0x00, 0x00, 0x01, 0x80, 0x00, 0x01, 0x03, 0x89, 0x36, 0x94, 0xcf, 0x8c, 0x72,
  0x00, 0x6a, 0x6f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x03, 0xe0, 0x03, 0xff, 0xc0,
  0xb5, 0x4c, 0x7d, 0xfc, 0x5b, 0xdd, 0x1d, 0xdb, 0x20, 0x03, 0x10, 0x50, 0xd5, 0xd1, 0xa0, 0x1e,
  0x74, 0x65, 0x73, 0x74, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x14, 0xa0, 0x03, 0xff, 0xc0, 0x00,
  0x0b, 0x8d, 0x10, 0x60, 0x00, 0x00, 0x30, 0x00, 0x00, 0x18, 0x00, 0x00, 0x0c, 0x00, 0x00, 0x06,
  0x00, 0x00, 0x03, 0x00, 0x00, 0x01, 0x80, 0x00, 0x02, 0x44, 0x89, 0x12, 0x24, 0x4f, 0x99, 0x32,
  0x00, 0x74, 0x65, 0x73, 0x74, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x14, 0xa0, 0x03, 0xff, 0xc0,
  0xf7, 0xd7, 0xb1, 0xbe, 0x29, 0xb4, 0x8f, 0xeb, 0x20, 0x03, 0x10, 0x50, 0xd5, 0xd1, 0xe0, 0x16,
  0x53, 0x65, 0x64, 0x61, 0x74, 0x69, 0x76, 0x65, 0x00, 0x00, 0x60, 0x20, 0x03, 0xff, 0xc0, 0x40,
  0x47, 0x0d, 0x90, 0x27, 0xc6, 0xc8, 0x13, 0x53, 0x68, 0x09, 0xe9, 0xb4, 0x04, 0xc0, 0xdb, 0x02,
  0x4c, 0x6d, 0x83, 0x00, 0x00, 0x01, 0x80, 0x00, 0x02, 0x50, 0x1b, 0x32, 0x54, 0xcf, 0x84, 0xc2,
  0x60, 0x53, 0x65, 0x64, 0x61, 0x74, 0x69, 0x76, 0x65, 0x00, 0x00, 0x60, 0x20, 0x03, 0xff, 0xc0,
  0xf0, 0x65, 0x29, 0x60, 0x59, 0xfa, 0xdf, 0xcc, 0x20, 0x03, 0x10, 0x50, 0xd5, 0xd2, 0x00, 0x46,
  0x63, 0x74, 0x63, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x70, 0x34, 0x03, 0xff, 0xc0, 0x40,
  0x41, 0xc8, 0x00, 0x22, 0xc6, 0xc8, 0x14, 0x13, 0x64, 0x09, 0xd9, 0xb4, 0x04, 0x70, 0xda, 0x02,
  0x80, 0x6d, 0x81, 0x32, 0x36, 0xc1, 0x80, 0x00, 0x22, 0x8d, 0x8d, 0x12, 0x94, 0x3f, 0x99, 0x09,
  0x40, 0x63, 0x74, 0x63, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x70, 0x34, 0x03, 0xff, 0xc0,
  0x97, 0x0f, 0x16, 0x1c, 0x05, 0xe1, 0xa1, 0x96, 0x20, 0x03, 0x10, 0x50, 0xd5, 0xd1, 0xc0, 0x1e,
  0x6a, 0x6f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x88, 0x60, 0x03, 0xff, 0xc0, 0x00,
  0x43, 0x4b, 0x90, 0x21, 0xa5, 0xd0, 0x10, 0xd2, 0xec, 0x08, 0x69, 0x78, 0x04, 0x34, 0xbd, 0x02,
  0x1a, 0x5f, 0x01, 0x0d, 0x2f, 0xc0, 0x86, 0x97, 0xe1, 0x03, 0x89, 0x36, 0x94, 0xcf, 0x8c, 0x72,
  0x00, 0x6a, 0x6f, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x88, 0x60, 0x03, 0xff, 0xc0,
  0xaf, 0x98, 0x70, 0x00, 0x91, 0x04, 0xef, 0xbc, 0x40, 0x0a, 0x00, 0xb0, 0xd5, 0xd2, 0xde, 0x4e,
  0x44, 0x61, 0x72, 0x6b, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x88, 0x00, 0x0a, 0x6b, 0xb4, 0x1a,
  0x14, 0x40, 0xba, 0xa8, 0x7b, 0x90, 0x10, 0x00, 0x00, 0x14, 0x2e, 0x0c, 0x00, 0x00, 0x06, 0x50,
  0xb0, 0x1d, 0x10, 0xf1, 0x1f, 0x82, 0x5c, 0x12, 0x81, 0x31, 0x1c, 0x31, 0x5a, 0x17, 0x82, 0x70,
  0x0f, 0x01, 0xc8, 0x20, 0xd0, 0xf5, 0x1b, 0x61, 0x80, 0x10, 0x62, 0x76, 0x2e, 0x31, 0x39, 0x43,
  0xc3, 0x83, 0x19, 0x32, 0x29, 0x24, 0x71, 0x55, 0x18, 0xd2, 0x84, 0x0f, 0xa1, 0x73, 0x1b, 0xd0,
  0xf9, 0x22, 0xc2, 0xba, 0x1a, 0x23, 0x05, 0x4d, 0x71, 0x87, 0x23, 0xe2, 0xf7, 0x0b, 0x60, 0xef,
  0x10, 0xe1, 0x10, 0x22, 0xb3, 0xcf, 0x1c, 0xe2, 0x03, 0x1d, 0x41, 0x3a, 0x2d, 0xc0, 0xf2, 0x1f,
  0xb2, 0x2f, 0x52, 0xd0, 0x41, 0x08, 0x40, 0xaf, 0x00, 0x80, 0x16, 0x03, 0x6e, 0xee, 0xee, 0xee,
  0xee, 0xee, 0x8e, 0xc8, 0xcc, 0x88, 0x88, 0x88, 0x88, 0x80, 0x00, 0x07, 0xff, 0xff, 0xbf, 0xff,
  0xfd, 0xff, 0xff, 0xff, 0xff, 0xff, 0xf5, 0x7f, 0xff, 0xff, 0xff, 0xc7, 0xf7, 0xff, 0xff, 0xf8,
  0xa1, 0x69, 0x58, 0xa2, 0x2e, 0x37, 0x51, 0x5b, 0x40, 0x0a, 0x00, 0xb0, 0xd5, 0xd2, 0x60, 0xf6,
  0x56, 0x61, 0x6e, 0x79, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x38, 0x00, 0x00, 0xd6, 0x60, 0x7a,
  0x15, 0x40, 0x3a, 0xac, 0xff, 0xf1, 0x10, 0x00, 0x00, 0x04, 0x08, 0x04, 0x00, 0x00, 0x53, 0x80,
  0x00, 0x00, 0x03, 0x25, 0x00, 0x00, 0x00, 0x16, 0x40, 0x00, 0x00, 0x02, 0xd4, 0x00, 0x00, 0x00,
  0x12, 0xc0, 0x00, 0x00, 0x01, 0x2b, 0x00, 0x00, 0x00, 0x19, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0xf4, 0x29, 0x42, 0x08,
  0xc6, 0xa7, 0x91, 0x6c, 0xff, 0xff, 0xff, 0xff, 0x40, 0x0a, 0x00, 0xb0, 0xd5, 0xd2, 0xc0, 0xea,
  0x56, 0x61, 0x6e, 0x79, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x38, 0x00, 0x00, 0xd6, 0x60, 0x7a,
  0x15, 0x40, 0x3a, 0xac, 0xff, 0xf1, 0x14, 0x00, 0x00, 0x04, 0x08, 0x04, 0x00, 0x00, 0x53, 0x80,
  0x00, 0x00, 0x03, 0x25, 0x00, 0x00, 0x00, 0x16, 0x40, 0x00, 0x00, 0x02, 0xd4, 0x00, 0x00, 0x00,
  0x12, 0xc0, 0x00, 0x00, 0x01, 0x2b, 0x00, 0x00, 0x00, 0x19, 0x10, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x08, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x01, 0xf4, 0x29, 0x42, 0x08,
  0x04, 0x00, 0x32, 0xc8, 0xff, 0xff, 0xff, 0xff, 0x40, 0x0a, 0x00, 0xb0, 0xd5, 0xd2, 0x80, 0x0a,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x64, 0xc0, 0x90, 0x01, 0xff, 0xff, 0xff, 0xff, 0x40, 0x0a, 0x00, 0xb0, 0xd5, 0xd2, 0xa0, 0x0a,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x0e, 0xa8, 0x32, 0xa5, 0xff, 0xff, 0xff, 0xff, 0x02, 0x0f, 0x01, 0x00, 0xd5, 0xd2, 0xb0, 0x0a,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00,
  0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
};

/******************************************
   Setup
 *****************************************/
void setup() {
  // Set Reset Pin(PD4) to Output
  DDRD |= (1 << 4);
  // Pull Reset(PD4) low until we are ready
  PORTD &= ~(1 << 4);

  // Set Eeprom Clock Pin(PD3) to Output
  DDRD |= (1 << 3);
  // Output a high signal
  PORTD |= (1 << 3);

  // Set Eeprom Data Pin(PD2) to Input
  DDRD &= ~(1 << 2);

  // Pull RESET(PD4) high to start eeprom
  PORTD |= (1 << 4);

  // Start Serial Monitor
  Serial.begin(9600);
  Serial.println("");
  Serial.println("N64 EEPROM WRITER");
  Serial.println("Send anything to start: _");
  Serial.println("");

  while (Serial.available() == 0) {
  }

  //Serial.println("Printing save file from Arduino sketch...");
  //printSave();
  //Serial.println("Reading EEPROM...");
  //readEeprom();
  //Serial.println("Resetting EEPROM...");
  //resetEeprom();
  //Serial.println("Erasing EEPROM...");
  //eraseEeprom();
  //Serial.println("");
  //Serial.println("Resetting EEPROM...");
  //resetEeprom();

  Serial.println("Reading EEPROM...");
  readEeprom();
  resetEeprom();
  Serial.println("Writing EEPROM...");
  writeEeprom();
  Serial.println("");
  resetEeprom();
  Serial.println("Reading EEPROM...");
  readEeprom();
}

/******************************************
  Eeprom functions
*****************************************/
// Send a clock pulse of 2us length, 50% duty, 500kHz
void pulseClock_N64(unsigned int times) {
  for (unsigned int i = 0; i < (times * 2); i++) {
    // Switch the clock pin to 0 if it's 1 and 0 if it's 1
    PORTD ^= (1 << 3);
    // without the delay the clock pulse would be 1.5us and 666kHz
    //__asm__("nop\n\t""nop\n\t""nop\n\t""nop\n\t"));
  }
}

// Send one byte of data to eeprom
void sendData(byte data) {
  for (byte i = 0; i < 8; i++) {
    // pull data line low
    N64_LOW;

    // if current bit is 1, pull high after ~1us, 2 cycles
    if (data >> 7) {
      pulseClock_N64(2);
      N64_HIGH;
      pulseClock_N64(6);
    }
    // if current bit is 0 pull high after ~3us, 6 cycles
    else {
      pulseClock_N64(6);
      N64_HIGH;
      pulseClock_N64(2);
    }

    // rotate to the next bit
    data <<= 1;
  }
}

// Send stop bit to eeprom
void sendStop() {
  N64_LOW;
  pulseClock_N64(2);
  N64_HIGH;
  pulseClock_N64(4);
}

// Capture 8 bytes in 64 bits into bit array tempBits
void readData() {
  for (byte i = 0; i < 64; i++) {
    // pulse clock until we get response from eeprom
    while (N64_QUERY) {
      pulseClock_N64(1);
    }

    // Skip over the 1us low part of a high bit
    pulseClock_N64(3);

    // Read bit
    tempBits[i] = N64_QUERY;

    // wait for line to go high again
    while (!N64_QUERY) {
      pulseClock_N64(1);
    }
  }
}

// Reset Eeprom
void resetEeprom() {
  delay(100);
  // Pull Reset(PD4) low
  PORTD &= ~(1 << 4);
  delay(100);
  // Pull RESET(PD4) high
  PORTD |= (1 << 4);
}

// Dump Save to Serial Monitor
void printSave() {
  char myBuffer[3];

  for (byte i = 0; i < (eepPages / 64); i++) {
    Serial.print("Page: ");
    Serial.println(i);

    // Load eepBuffer with 512 bytes
    for (int e = 0; e < 512; e++) {
      eepBuffer[e] = pgm_read_byte(&eepSave[i * 512 + e]);
    }

    for (byte pageNumber = 0; pageNumber < 32; pageNumber++) {
      // Send data to write
      for (byte j = 0; j < 16; j++) {
        itoa(eepBuffer[pageNumber * 16 + j], myBuffer, 16);
        for (size_t i = 0; i < 2 - strlen(myBuffer); i++) {
          Serial.print("0");
        }
        // Now print the significant bits
        Serial.print(myBuffer);
        Serial.print(" ");
      }
      Serial.println(" ");
    }
    Serial.println(" ");
  }
  Serial.println(" ");
}

// Erase Eeprom
void eraseEeprom() {
  for (byte i = 0; i < (eepPages / 64); i++) {
    Serial.print("Page: ");
    Serial.println(i);

    // Load eepBuffer with 512 bytes
    for (int e = 0; e < 512; e++) {
      eepBuffer[e] = 0xFF;
    }

    for (byte pageNumber = 0; pageNumber < 64; pageNumber++) {
      // Disable interrupts for more uniform clock pulses
      noInterrupts();

      // Wait ~50ms between page writes or eeprom will have write errors
      pulseClock_N64(26000);

      // Send write command
      sendData(0x05);
      // Send page number
      sendData(pageNumber + (i * 64));
      // Send data to write
      for (byte j = 0; j < 8; j++) {
        sendData(eepBuffer[(pageNumber * 8) + j]);
      }
      sendStop();

      interrupts();
    }
  }
}

// Write Eeprom to cartridge
void writeEeprom() {
  for (byte i = 0; i < (eepPages / 64); i++) {
    Serial.print("Page: ");
    Serial.println(i);

    // Load eepBuffer with 512 bytes
    for (int e = 0; e < 512; e++) {
      eepBuffer[e] = pgm_read_byte(&eepSave[i * 512 + e]);
    }

    for (byte pageNumber = 0; pageNumber < 64; pageNumber++) {
      // Disable interrupts for more uniform clock pulses
      noInterrupts();

      // Wait ~50ms between page writes or eeprom will have write errors
      pulseClock_N64(26000);

      // Send write command
      sendData(0x05);
      // Send page number
      sendData(pageNumber + (i * 64));
      // Send data to write
      for (byte j = 0; j < 8; j++) {
        sendData(eepBuffer[(pageNumber * 8) + j]);
      }
      sendStop();

      interrupts();
    }
  }
}

// Dump Eeprom to Serial Monitor
void readEeprom() {
  // Wait 0.6ms
  pulseClock_N64(300);

  for (byte i = 0; i < (eepPages / 64); i++) {
    Serial.print("Page: ");
    Serial.println(i);

    for (byte pageNumber = 0; pageNumber < 64; pageNumber++) {
      // Disable interrupts for more uniform clock pulses
      noInterrupts();

      // Send read command
      sendData(0x04);
      // Send Page number
      sendData(pageNumber + (i * 64));
      // Send stop bit
      sendStop();

      // read data
      readData();
      sendStop();

      interrupts();

      // OR 8 bits into one byte for a total of 8 bytes
      for (byte j = 0; j < 64; j += 8) {
        eepBuffer[(pageNumber * 8) + (j / 8)] = tempBits[0 + j] << 7 | tempBits[1 + j] << 6 | tempBits[2 + j] << 5 | tempBits[3 + j] << 4 | tempBits[4 + j] << 3 | tempBits[5 + j] << 2 | tempBits[6 + j] << 1 | tempBits[7 + j];
      }
      // Wait ~0.6ms between pages or eeprom will lock up
      pulseClock_N64(300);
    }

    // Print 64 pages at once to Serial
    char myBuffer[3];

    for (int d = 0; d < 32; d++) {
      for (int f = 0; f < 16; f++) {
        itoa(eepBuffer[d * 16 + f], myBuffer, 16);
        for (size_t i = 0; i < 2 - strlen(myBuffer); i++) {
          Serial.print("0");
        }
        // Now print the significant bits
        Serial.print(myBuffer);
        Serial.print(" ");
      }
      Serial.println(" ");
    }
    Serial.println(" ");
  }
  Serial.println(" ");
}

//******************************************
// Loop
//******************************************
void loop() {
}

//******************************************
// End of File
//******************************************

[weleusernamegod]

Hi Sanni,

Wow, what a response! This has exceeded all my expectations, thank you so much! I'm putting it all together now and will try it out as soon as I can.

[weleusernamegod]

I have just successfully reflashed a 100% savegame to EEPROM! On the first few attempts, the script got stuck reading the EEPROM - the serial monitor just printed 'Re' and then stopped. After trying it with another salvaged EEPROM from a donor cartridge, it worked perfectly! So my game's chip was indeed broken.

Thanks a lot Sanni for your help :)

[sanni]

Glad it worked out. It was a nice coding exercise. I was surprised myself that the code just worked on the Arduino Uno without any fuss. I did use an older version of my code base though because it doesn't need the clock generator so it's easier to put together.

Even more interesting: It gave me some new insights about the N64 eeprom because the code wouldn't work at first without resetting the eeprom between the different operations. Something I currently are not doing the OSCR code. So if in the future people report the eeprom reading/writing not to work I'm going to put a reset between the read/write there too.