ADXL313 accelerometer and Raspberry Pi Pico Arduino example

In this article we connect the ever popular ADXL313 accelerometer to a raspberry Pi Pico and we will then display readings via the serial monitor window. We are using the Arduino IDE.

Lets look at the sensor first

Features

The ADXL313 is a small, thin, low power, 3-axis accelerometer with high resolution (13-bit) measurement up to ±4g. Digital output data is formatted as 16-bit twos complement and is accessible through either a serial port interface (SPI) (3-wire or 4-wire) or I²C digital interface.

Parts Required

Name	Link
Raspberry Pi Pico		Aliexpress link Amazon Ebay
ADXL313		Aliexpress link Ebay link
Connecting cables		Aliexpress link Amazon Ebay

Schematic/Connection

Here is a layout in fritzing to show this

Code Example

I used the Sparkfun ADXL313 library and  this is the default example which worked, there are several examples to experiment with

The library needs updated to work with the Raspberry Pi Pico – this issue is detailed here – https://github.com/sparkfun/SparkFun_ADXL313_Arduino_Library/issues/5

Look for the following in SparkFunADXL313.cpp

//Initializes the sensor with basic settings via SPI
//Returns false if sensor is not detected
boolean ADXL313::beginSPI(uint8_t CS_pin, SPIClass &spiPort)
{
    _CS = CS_pin;
    _spiPort = &spiPort;
    I2C = false;
//_spiPort->begin(_CS); // throws a compile error, no such function
_spiPort->begin();
//_spiPort->setDataMode(SPI_MODE3); // old way of doing SPI settings, now you must pass in an SPISettings object
_spiPort->beginTransaction(SPISettings(2000000, MSBFIRST, SPI_MODE3));
    pinMode(_CS, OUTPUT);
    digitalWrite(_CS, HIGH);

    // since we can't simply check for an "ACK" like in I2C,
    // we will check PART ID, to verify that it's there and working
  	if (checkPartId() == false) // Check for sensor Part ID
    	return (false);

  	return (true); //We're all setup!
}

And the basic example

#include <Wire.h>
#include "SparkFunADXL313.h" //Click here to get the library: http://librarymanager/All#SparkFun_ADXL313
ADXL313 myAdxl;

void setup()
{
  Serial.begin(115200);
  Serial.println("Example 1 - Reading values from ADXL313");

  Wire.begin();

  if (myAdxl.begin() == false) //Begin communication over I2C
  {
    Serial.println("The sensor did not respond. Please check wiring.");
    while(1); //Freeze
  }
  Serial.print("Sensor is connected properly.");
  
  myAdxl.measureModeOn(); // wakes up the sensor from standby and puts it into measurement mode
}

void loop()
{
  if(myAdxl.dataReady()) // check data ready interrupt, note, this clears all other int bits in INT_SOURCE reg
  {
    myAdxl.readAccel(); // read all 3 axis, they are stored in class variables: myAdxl.x, myAdxl.y and myAdxl.z
    Serial.print("x: ");
    Serial.print(myAdxl.x);
    Serial.print("\ty: ");
    Serial.print(myAdxl.y);
    Serial.print("\tz: ");
    Serial.print(myAdxl.z);
    Serial.println();
  }
  else
  {
    Serial.println("Waiting for dataReady.");
  }  
  delay(250);
}

Output

x: 10 y: -21 z: -512
x: 95 y: 57 z: -512
x: 60 y: -145 z: -512
x: -256 y: -210 z: -512
x: -512 y: 424 z: 511
x: -512 y: -512 z: 250
x: -164 y: 159 z: -512
x: -17 y: -219 z: -512

Links

https://www.analog.com/media/en/technical-documentation/data-sheets/adxl313.pdf

https://github.com/sparkfun/SparkFun_ADXL313_Arduino_Library