gbreader.ino

// try to read a badly damaged 32k Gameboy Cartridge

const uint32_t aPins[16] = { PB8, PB9, PC13, PB7, PA0, PA1, PA2, PA3, 
                     PA4, PA5, PA6, PA7,  PB0, PB1, PB10, PB11 };

const uint32_t dPins[8] = { PB4, PB3, PA9, PA8, PB15, PB14, PB13,  PA10 };
// all 5V tolerant: PB4, PB3, PA9, PA8, PB15, PB14, PB13, PA10
uint16_t address;
uint16_t RD = PB5;

#define CHUNK 0x4
#define VERIFY_TIMES 5

uint8_t data[CHUNK];
uint8_t dataCheck[CHUNK];

void setAddress(uint16_t address) {
  uint16_t mask = 1;
  for (unsigned bit = 0 ; mask ; bit++, mask <<= 1)
    digitalWrite(aPins[bit], (mask & address) ? 1 : 0);
}

uint8_t readData() {
  uint8_t out = 0;
  uint8_t mask = 1;
  for (unsigned bit = 0 ; mask ; bit++, mask <<= 1)
    if (digitalRead(dPins[bit]))
      out |= mask;
  return out;
}

void waitTime(uint16_t address, uint8_t value, uint32_t ms) {
  setAddress(address);
  uint32_t t0 = millis();
  do {
    if (readData() != value)
      t0 = millis();
  } while (millis()-t0 < ms);
}

uint8_t readByte(uint16_t address, unsigned del) {
  // 10,10,1: 30x5
  // 10,10,10: better
  // 15,15,10: better
  // 5,15,10: decent , 4.5v better
  // 1,5,10
  setAddress(address);
  digitalWrite(RD,0);
  for (int i=0;i<200;i++);
//  delayMicroseconds(0);
  uint8_t v = readData();
//  digitalWrite(RD,1);
//  delayMicroseconds(5);
  return v;
}

void dumpChunk(uint8_t* d) {
  char buf[3];
  for (unsigned i = 0 ; i < CHUNK ; i++) {
    sprintf(buf, "%02x", (unsigned)d[i]);
    Serial.write((uint8*)buf, 2);
  }
}

void readChunkRaw(uint8_t* d, uint16_t address, unsigned del) {
  for (int i=0; i<CHUNK; i++)
    d[i]=readByte(address+i, del);
}

void readChunk(uint16_t address) {
  int count = 0;
  int errorCount=0;
  int numVerifies = VERIFY_TIMES;
  unsigned del = 10;
  do {
    readChunkRaw(data, address, del);
    if (count == 0 || memcmp(data,dataCheck,CHUNK)) {
      if (count>0) {
/*        Serial.write('\n');
        Serial.println(count);
        Serial.write('+');
        dumpChunk(data);
        Serial.write('\n'); */
        //Serial.write('*');
        del = 250;
        errorCount++;
        if (errorCount > 80)
          numVerifies = 3;
      }
    
      count = 1;
      memcpy(dataCheck,data,CHUNK);
    }
    else {
      count++;      
    }
  } while(count < numVerifies);
}

void setup() {
  for (int i=0;i<15;i++)
    pinMode(aPins[i],OUTPUT);
  for (int i=0;i<8;i++)
    pinMode(dPins[i],INPUT_PULLDOWN);

  pinMode(RD,OUTPUT);
  digitalWrite(RD,0);

  pinMode(PB12,OUTPUT);
  digitalWrite(PB12,1);

  Serial.begin();

  delay(3000);

  digitalWrite(PB12,0);

  address = 0;
//  setAddress(0b101010101010101);
//  while(1);
}

uint8_t carefulRead(uint16_t address) {
  setAddress(address);
  uint8_t datum = 0;
  for (int i=0;i<20;i++) {
    digitalWrite(RD,0);
    delayMicroseconds(1); //1
    for (int j=0;j<120;j++)
      datum |= readData();
    digitalWrite(RD,1);
    delayMicroseconds(100); //50
  }
  return datum;
}

void zzloop() {
  uint8_t data[4000];
  address = 0x7FF5;
  digitalWrite(RD,0);
  delayMicroseconds(100); // 7ff3 = c3, 7ff5 = 69
  for (; address <= 0x7ff5; address++) {
    Serial.println(address,HEX);
    setAddress(address);
    digitalWrite(RD,0);
    delayMicroseconds(1);
//    for (volatile int j=0;j<10;j++);
    for (int i=0;i<4000;i++) {
      //delayMicroseconds(50);
      data[i] = readData();
    }
    digitalWrite(RD,1);
    for (int i=0;i<4000;i++) {
      Serial.print(data[i],HEX);
      Serial.print(" ");
    }
    Serial.write('\n');
  }
//  while(1);
}

void loop() {
  if (address >= 0x8000)
    return;
    
  char buf[12];
  sprintf(buf, "%04x: ", (unsigned)address);
  Serial.print(buf);
  for (int i=0; i<0x20; i++) {
    uint8_t r = carefulRead(address);
    sprintf(buf, "%02x", r);
    Serial.print(buf);
    address++;
  }
  Serial.write('\n');
}

void cloop() {
  char buf[12];
  sprintf(buf, "\n%04x: ", (unsigned)address);
  Serial.print(buf);
  readChunk(address);
  dumpChunk(data);
  address += CHUNK;
  if (address >= 0x8000) {  
    Serial.write('\n');
    while(1) ; 
  }
}