MicroscopeController/MouseIO.ino at master · knud/MicroscopeController · GitHub

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/*
 * Pin 5 is the mouse data pin, pin 6 is the clock pin
 * Feel free to use whatever pins are convenient.
 */
#define MDATA 18
#define MCLK 19


void mouse_write(char data)
{
  char i;
  char parity = 1;

  //  Serial.print("Sending ");
  //  Serial.print(data, HEX);
  //  Serial.print(" to mouse\n");
  //  Serial.print("RTS");
  /* put pins in output mode */
  gohi(MDATA);
  gohi(MCLK);
  delayMicroseconds(300);
  golo(MCLK);
  delayMicroseconds(300);
  golo(MDATA);
  delayMicroseconds(10);
  /* start bit */
  gohi(MCLK);
  /* wait for mouse to take control of clock); */
  while (digitalRead(MCLK) == HIGH)
    ;
  /* clock is low, and we are clear to send data */
  for (i=0; i < 8; i++) {
    if (data & 0x01) {
      gohi(MDATA);
    }
    else {
      golo(MDATA);
    }
    /* wait for clock cycle */
    while (digitalRead(MCLK) == LOW)
      ;
    while (digitalRead(MCLK) == HIGH)
      ;
    parity = parity ^ (data & 0x01);
    data = data >> 1;
  }
  /* parity */
  if (parity) {
    gohi(MDATA);
  }
  else {
    golo(MDATA);
  }
  while (digitalRead(MCLK) == LOW)
    ;
  while (digitalRead(MCLK) == HIGH)
    ;
  /* stop bit */
  gohi(MDATA);
  delayMicroseconds(50);
  while (digitalRead(MCLK) == HIGH)
    ;
  /* wait for mouse to switch modes */
  while ((digitalRead(MCLK) == LOW) || (digitalRead(MDATA) == LOW))
    ;
  /* put a hold on the incoming data. */
  golo(MCLK);
  //  Serial.print("done.\n");
}

/*
 * Get a byte of data from the mouse
 */
char mouse_read(void)
{
  char data = 0x00;
  int i;
  char bit = 0x01;

  //  Serial.print("reading byte from mouse\n");
  /* start the clock */
  gohi(MCLK);
  gohi(MDATA);
  delayMicroseconds(50);
  while (digitalRead(MCLK) == HIGH)
    ;
  delayMicroseconds(5);  /* not sure why */
  while (digitalRead(MCLK) == LOW) /* eat start bit */
    ;
  for (i=0; i < 8; i++) {
    while (digitalRead(MCLK) == HIGH)
      ;
    if (digitalRead(MDATA) == HIGH) {
      data = data | bit;
    }
    while (digitalRead(MCLK) == LOW)
      ;
    bit = bit << 1;
  }
  /* eat parity bit, which we ignore */
  while (digitalRead(MCLK) == HIGH)
    ;
  while (digitalRead(MCLK) == LOW)
    ;
  /* eat stop bit */
  while (digitalRead(MCLK) == HIGH)
    ;
  while (digitalRead(MCLK) == LOW)
    ;

  /* put a hold on the incoming data. */
  golo(MCLK);
  //  Serial.print("Recvd data ");
  //  Serial.print(data, HEX);
  //  Serial.print(" from mouse\n");
  return data;
}

void mouse_init()
{
  gohi(MCLK);
  gohi(MDATA);
//  Serial.print("Sending reset to mouse\n");
  mouse_write(0xff);
  mouse_read();  /* ack byte */
//  Serial.print("Read ack byte1\n");
  mouse_read();  /* blank */
  mouse_read();  /* blank */
//  Serial.print("Sending remote mode code\n");
  mouse_write(0xf0);  /* remote mode */
  mouse_read();  /* ack */
//  Serial.print("Read ack byte2\n");
  delayMicroseconds(100);
}