Arduino Due and MMA8451 sensor example

The MMA8451 is a low-power accelerometer with 14 bits of resolution, with the following features:

Embedded functions with flexible user-programmable options, configurable to two interrupt pins
Embedded interrupt functions for overall power savings relieving the host processor from continuously polling data
Access to both low-pass filtered data as well as high-pass filtered data, which minimizes the data analysis required for jolt detection and faster transitions
Inertial wake-up interrupt signals from any combination of the configurable embedded functions allowing the MMA8451Q to monitor events and remain in a low-power mode during periods of inactivity

Features

1.95 to 3.6-volt supply voltage
1.6 to 3.6-volt interface voltage
±2g/±4g/±8g dynamically selectable full-scale
Output data rates (ODR) from 1.56 Hz to 800 Hz
99 μg/√Hz noise
14-bit and 8-bit digital output
I²C digital output interface (operates to 2.25 MHz with 4.7 kΩ pull-up)
Two programmable interrupt pins for seven interrupt sources
Three embedded channels of motion detection
- Freefall or motion detection: one channel
- Pulse detection: one channel
- Jolt detection: one channel
Orientation (portrait/landscape) detection with programmable hysteresis
Automatic ODR change for auto-wake and return to sleep
32 sample FIFO
High pass filter data available per sample and through the FIFO
Self-test

Again due to the size and package of the module its easier to buy a module, here is one that I purchased.

Connection

I used the following connection from the module above to my Arduino Due

Arduino Due Connection	Module Connection
3v3	VCC_IN
Gnd	Gnd
SDA 20	SDA
SCL 21	SCL

Here is a layout showing this

Code

This requires the Adafruit library from https://github.com/adafruit/Adafruit_MMA8451_Library/archive/master.zip

I had to edit the Adafruit header file called Adafruit_MMA8451.h as my device was address 0x1c (28), I discovered this using an I2C scanner

#define MMA8451_DEFAULT_ADDRESS (0x1C)

[codesyntax lang=”cpp”]

#include <Wire.h>
#include "Adafruit_MMA8451.h"
#include <Adafruit_Sensor.h>

Adafruit_MMA8451 mma = Adafruit_MMA8451();

void setup(void) {
Serial.begin(9600);

Serial.println("Adafruit MMA8451 test!");

if (! mma.begin()) {
Serial.println("Couldnt start");
while (1);
}
Serial.println("MMA8451 found!");

mma.setRange(MMA8451_RANGE_2_G);

Serial.print("Range = "); Serial.print(2 << mma.getRange());
Serial.println("G");

}

void loop() {
// Read the 'raw' data in 14-bit counts
mma.read();
Serial.print("X:\t"); Serial.print(mma.x);
Serial.print("\tY:\t"); Serial.print(mma.y);
Serial.print("\tZ:\t"); Serial.print(mma.z);
Serial.println();

/* Get a new sensor event */
sensors_event_t event;
mma.getEvent(&event);

/* Display the results (acceleration is measured in m/s^2) */
Serial.print("X: \t"); Serial.print(event.acceleration.x); Serial.print("\t");
Serial.print("Y: \t"); Serial.print(event.acceleration.y); Serial.print("\t");
Serial.print("Z: \t"); Serial.print(event.acceleration.z); Serial.print("\t");
Serial.println("m/s^2 ");

/* Get the orientation of the sensor */
uint8_t o = mma.getOrientation();

switch (o) {
case MMA8451_PL_PUF:
Serial.println("Portrait Up Front");
break;
case MMA8451_PL_PUB:
Serial.println("Portrait Up Back");
break;
case MMA8451_PL_PDF:
Serial.println("Portrait Down Front");
break;
case MMA8451_PL_PDB:
Serial.println("Portrait Down Back");
break;
case MMA8451_PL_LRF:
Serial.println("Landscape Right Front");
break;
case MMA8451_PL_LRB:
Serial.println("Landscape Right Back");
break;
case MMA8451_PL_LLF:
Serial.println("Landscape Left Front");
break;
case MMA8451_PL_LLB:
Serial.println("Landscape Left Back");
break;
}
Serial.println();
delay(500);

}

[/codesyntax]