No new values from Accelerometer

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1

I have a MMA8462Q (Redbot acceleromoter) that I can not get a good read from. I have it wired up properly, its A5 to SCL and A4 to SDA, ground to ground and 5v to 5v. I get a reading from it using the sketch below but they never change.

I always get:

0.00

75.00

12.00

Not matter how much I shake that accelerometer it never changes. Thanks in advance

#include <Wire.h>
float test;
void setup()
{
  Wire.begin();        // join i2c bus (address optional for master)
  Serial.begin(9600);  // start serial for output
}

void loop()
{
  Wire.requestFrom(29, 3);    // request 6 bytes from slave device #2

  while(Wire.available())    // slave may send less than requested
  { 
    test = Wire.read(); // receive a byte as character
    Serial.println(test);
  }

  delay(500);
}
2

The MMA8462Q is a 3.3V device. Does your breakout board have a voltage regulator and level shifters?

Assuming it does, the program you posted is pretty minimal and it does not look like it should work at all. Are you sure that the accelerometer does not need to be initialized and that you are reading out the correct registers? Normally one would read out 6 bytes, beginning at register 1, for the three acceleration values.

Consult the Redbot library for some examples.

3

The redbot accelerometer board has level shifters and pullups, so that should be OK.

I agree, the redbot Arduino library should be your starting point for the code.

/mike