Arduino Apple ADB fun

adbfun.ino

#define BYTE_TO_BINARY_PATTERN "%c%c%c%c%c%c%c%c\n"
#define BYTE_TO_BINARY(val) \
  (val & 0x80 ? '1' : '0'), \
  (val & 0x40 ? '1' : '0'), \
  (val & 0x20 ? '1' : '0'), \
  (val & 0x10 ? '1' : '0'), \
  (val & 0x8 ? '1' : '0'), \
  (val & 0x4 ? '1' : '0'), \
  (val & 0x2 ? '1' : '0'), \
  (val & 0x1 ? '1' : '0')
void setup() {
  Serial.begin(9600);
  pinMode(2, INPUT_PULLUP);
}
#define NUM 256
unsigned long startTime, endTime, diff;
unsigned long diffs[NUM];
unsigned long index = 0;
unsigned char command;
char printBuffer[64];
boolean waitingForStart = true;
unsigned char deviceId = 3;
void writeOne() {
  digitalWrite(2, LOW);
  delayMicroseconds(35);
  digitalWrite(2, HIGH);
  delayMicroseconds(65);
}
void writeZero() {
  digitalWrite(2, LOW);
  delayMicroseconds(65);
  digitalWrite(2, HIGH);
  delayMicroseconds(35);
}
unsigned long readPulse() {
  while(digitalRead(2)) {}
  startTime = micros();
  while(!digitalRead(2)) {}
  endTime = micros();
  return (endTime - startTime);
}
boolean isHigh(unsigned long d) {
  return (d > (35 - 10) && d < (35 + 10));
}
boolean isLow(unsigned long d) {
  return (d > (65 - 10) && d < (65 + 10));
}
void loop() {
  diff = readPulse();
  if (diff > 750 && diff < 850) {
    index = 0;
    waitingForStart = false;
  } else if (!waitingForStart) {
    diffs[index] = diff;
    index++;
    if (index == 8) {
      command = 0;
      for (index = 0; index < 8; index++) {
        if (isHigh(diffs[index])) {
          command |= (1 << (7 - index));
        } else if (isLow(diffs[index])) {
          command &= ~(1 << (7 - index));
        }
      }
      if (command >> 4 == deviceId) {
        if (((command >> 2) & 3) == 3) {
          // Talk command
          if (command & 3 == 3) {
            // Register 3
            // Respond with some stuff
            delayMicroseconds(200);
            pinMode(2, OUTPUT);
            // '1' Start bit
            writeOne();
            // 15 reserved, 0
            writeZero();
            // 14 exceptional event, device specific, 1 if unused
            writeOne();
            // 13 service request enable, 1 = enabled
            writeOne();
            // 12 reserved, 0
            writeZero();
            // 11
            // 10
            //  9
            //  8 address
            // Send a random address, which is just going to be hardcoded as 6 here, because I'm lazy
            writeZero();
            writeOne();
            writeOne();
            writeZero();
            //  7
            //  6
            //  5
            //  4
            //  3
            //  2
            //  1
            //  0 device handler id
            writeZero();
            writeZero();
            writeZero();
            writeZero();
            writeZero();
            writeZero();
            writeZero();
            writeOne();
            // '0' stop bit
            writeZero();
            pinMode(2, INPUT_PULLUP);
          } else if (command & 3 == 0) {
            // Register 0
            // Respond with some stuff
            delayMicroseconds(200);
            pinMode(2, OUTPUT);
            // '1' Start bit
            writeOne();
            // 15 button status, 0 = down
            writeOne();
            // 14
            // 13
            // 12
            // 11
            // 10
            //  9
            //  8 Y move counts 2's complement form, negative = up
            writeZero();
            writeZero();
            writeZero();
            writeZero();
            writeZero();
            writeZero();
            writeZero();
            //  7 not used (always 0)
            writeZero();
            //  6
            //  5
            //  4
            //  3
            //  2
            //  1
            //  0 X move counts, negative = left
            writeZero();
            writeZero();
            writeZero();
            writeZero();
            writeZero();
            writeZero();
            writeOne();
            // '0' stop bit
            writeZero();
            pinMode(2, INPUT_PULLUP);
          }
        } else if (((command >> 2) & 3) == 2) {
          // Listen command
          // Listen Register 3
          if (command & 3 == 3) {
            for(index = 0; index < 19; index++) {
              diffs[index] = readPulse();
            }
            deviceId = (isHigh(diffs[6]) << 3) | (isHigh(diffs[7]) << 2) | (isHigh(diffs[8]) << 1) | (isHigh(diffs[9]));
            sprintf(printBuffer, "Going to DeviceId: %d\n", deviceId);
            Serial.print(printBuffer);
            for(index = 0; index < 19; index++) {
              sprintf(printBuffer, "%d\n", (isLow(diffs[index])) ? 0 : (isHigh(diffs[index])) ? 1 : diffs[index]);
              Serial.print(printBuffer);
            }
            Serial.print("Done.\n");
            // TODO: The host keeps sending us to different IDs (27 times!) and then polls register 0 very infrequently, so this is probably working wrongly? Or do we just need to do a sysrequest to actually send data?
            // (That's done by effectively wiping out the stop bit on any host command, holding it low for a total of 300usec. Then it waits to be addressed. If the host addresses some other device instead, do it again).
          } else {
            sprintf(printBuffer, BYTE_TO_BINARY_PATTERN, BYTE_TO_BINARY(command));
            Serial.print(printBuffer);
            Serial.print("Unknown Listen command:\n");
            for(index = 0; index < NUM; index++) {
              diffs[index] = readPulse();
            }
            for(index = 0; index < NUM; index++) {
              sprintf(printBuffer, "%d\n", (isLow(diffs[index])) ? 0 : (isHigh(diffs[index])) ? 1 : diffs[index]);
              Serial.print(printBuffer);
            }
            Serial.print("Done.\n");
            while(1) {}
          }
        }
        sprintf(printBuffer, BYTE_TO_BINARY_PATTERN, BYTE_TO_BINARY(command));
        Serial.print(printBuffer);
      }
      index = 0;
      waitingForStart = true;
    }
  }
}