Okay, I might have fried my Arduino Due, Help needed

Official Hardware Mega Due
1

Hi

I have been attempting to connect a L3G4200D Parallax gyroscope to the Arduino Due. I tried the following pin connections:

Gyro-->Due

SCL-->Pin 21(SCL)
SDA-->Pin 20(SDA)
Vin--> 5 V
GND--> GND

and the following code (the one provided by parallax for arduino)

#include <Wire.h>

#define CTRL_REG1 0x20
#define CTRL_REG2 0x21
#define CTRL_REG3 0x22
#define CTRL_REG4 0x23

int Addr = 105;                 // I2C address of gyro
int x, y, z;

void setup(){
  Wire.begin();
  Serial.begin(9600);
  writeI2C(CTRL_REG1, 0x1F);    // Turn on all axes, disable power down
  writeI2C(CTRL_REG3, 0x08);    // Enable control ready signal
  writeI2C(CTRL_REG4, 0x80);    // Set scale (500 deg/sec)
  delay(100);                   // Wait to synchronize 
}

void loop(){
  getGyroValues();              // Get new values
  // In following Dividing by 114 reduces noise
  Serial.print("Raw X:");  Serial.print(x / 114);  
  Serial.print(" Raw Y:"); Serial.print(y / 114);
  Serial.print(" Raw Z:"); Serial.println(z / 114);
  delay(500);                   // Short delay between reads
}

void getGyroValues () {
  byte MSB, LSB;

  MSB = readI2C(0x29);
  LSB = readI2C(0x28);
  x = ((MSB << 8) | LSB);

  MSB = readI2C(0x2B);
  LSB = readI2C(0x2A);
  y = ((MSB << 8) | LSB);

  MSB = readI2C(0x2D);
  LSB = readI2C(0x2C);
  z = ((MSB << 8) | LSB);
}

int readI2C (byte regAddr) {
    Wire.beginTransmission(Addr);
    Wire.write(regAddr);                // Register address to read
    Wire.endTransmission();             // Terminate request
    Wire.requestFrom(Addr, 1);          // Read a byte
    while(!Wire.available()) { };       // Wait for receipt
    return(Wire.read());                // Get result
}

void writeI2C (byte regAddr, byte val) {
    Wire.beginTransmission(Addr);
    Wire.write(regAddr);
    Wire.write(val);
    Wire.endTransmission();
}

The output in the serial window for this code was strange. I seemed to get reasonable rates when i rotated the gyro in the CCW direction but when rotated CW, instead of getting a negative rate i got something in the rage of 500-600 deg/sec. I posted about this problem on the parallax forums and they told me that i might have damaged my board due to the sensor being powered by the 5V pin. I knew that the Due I/O pins were not 5V tolerant but I had no idea this rule applied to the 5V pin itself. So I come to my question, have I fried my board?

P.S The sensor itself is fine, i checked it with an Uno

2

That gyro board works from 2.7V up so power it from 3.3V. The specs list the power
consumption for both 3.3V and 5V, so it clearly works at 3.3V.

In theory the I2C bus will only have been pulling up via resistors, perhaps 10k
ones, so it may have done no damage, but the Due pins absolutely cannot withstand
5V direct at all, you get no second chances. The protection diodes are weeny too
so tolerate only a 100uA or so IIRC.

Basically if there's any risk of 5V getting to a Due pin, you need to add protection
to that pin (schottkys to GND and 3.3V, and a series resistor). Powering the gyro module
from 3.3V prevents any risk.