Wemos Mini ADXL345 example

The ADXL345 is a small, thin, low power, 3-axis accelerometer with high resolution (13-bit) measurement at up to ±16g. Digital output data is formatted as 16-bit twos complement and is accessible through either a SPI (3- or 4-wire) or I2C digital interface.

The ADXL345 is well suited for mobile device applications. It measures the static acceleration of gravity in tilt-sensing applications, as well as dynamic acceleration resulting from motion or shock.

Its high resolution (4 mg/LSB) enables measurement of inclination changes less than 1.0°.

Several special sensing functions are provided. Activity and inactivity sensing detect the presence or lack of motion and if the acceleration on any axis exceeds a user-set level. Tap sensing detects single and double taps.

Free-fall sensing detects if the device is falling. These functions can be mapped to one of two interrupt output pins. An integrated, patent pending 32-level first in, first out (FIFO) buffer can be used to store data to minimize host processor intervention.

adxl345-module

 

Parts List

Here are the parts I used

 

Name Links
Wemos Mini
ADXL345
Connecting cables

 

Connection and layout

I used the following connection from the module above to my Wemos Mini

 

Wemos Mini Connection Module Connection
3v3 VCC
Gnd Gnd
SDA D2 SDA
SCL D1 SCL

 

Here is a layout for reference

wemos-adxl345_bb

 

Code

This needs the Adafruit library – https://github.com/adafruit/Adafruit_ADXL345

This is just the sensor test code from the library above

#include <Wire.h>
#include <Adafruit_Sensor.h>
#include <Adafruit_ADXL345_U.h>

/* Assign a unique ID to this sensor at the same time */
Adafruit_ADXL345_Unified accel = Adafruit_ADXL345_Unified(12345);

void displaySensorDetails(void)
{
 sensor_t sensor;
 accel.getSensor(&sensor);
 Serial.println("------------------------------------");
 Serial.print ("Sensor: "); Serial.println(sensor.name);
 Serial.print ("Driver Ver: "); Serial.println(sensor.version);
 Serial.print ("Unique ID: "); Serial.println(sensor.sensor_id);
 Serial.print ("Max Value: "); Serial.print(sensor.max_value); Serial.println(" m/s^2");
 Serial.print ("Min Value: "); Serial.print(sensor.min_value); Serial.println(" m/s^2");
 Serial.print ("Resolution: "); Serial.print(sensor.resolution); Serial.println(" m/s^2"); 
 Serial.println("------------------------------------");
 Serial.println("");
 delay(500);
}

void displayDataRate(void)
{
 Serial.print ("Data Rate: "); 
 
 switch(accel.getDataRate())
 {
 case ADXL345_DATARATE_3200_HZ:
 Serial.print ("3200 "); 
 break;
 case ADXL345_DATARATE_1600_HZ:
 Serial.print ("1600 "); 
 break;
 case ADXL345_DATARATE_800_HZ:
 Serial.print ("800 "); 
 break;
 case ADXL345_DATARATE_400_HZ:
 Serial.print ("400 "); 
 break;
 case ADXL345_DATARATE_200_HZ:
 Serial.print ("200 "); 
 break;
 case ADXL345_DATARATE_100_HZ:
 Serial.print ("100 "); 
 break;
 case ADXL345_DATARATE_50_HZ:
 Serial.print ("50 "); 
 break;
 case ADXL345_DATARATE_25_HZ:
 Serial.print ("25 "); 
 break;
 case ADXL345_DATARATE_12_5_HZ:
 Serial.print ("12.5 "); 
 break;
 case ADXL345_DATARATE_6_25HZ:
 Serial.print ("6.25 "); 
 break;
 case ADXL345_DATARATE_3_13_HZ:
 Serial.print ("3.13 "); 
 break;
 case ADXL345_DATARATE_1_56_HZ:
 Serial.print ("1.56 "); 
 break;
 case ADXL345_DATARATE_0_78_HZ:
 Serial.print ("0.78 "); 
 break;
 case ADXL345_DATARATE_0_39_HZ:
 Serial.print ("0.39 "); 
 break;
 case ADXL345_DATARATE_0_20_HZ:
 Serial.print ("0.20 "); 
 break;
 case ADXL345_DATARATE_0_10_HZ:
 Serial.print ("0.10 "); 
 break;
 default:
 Serial.print ("???? "); 
 break;
 } 
 Serial.println(" Hz"); 
}

void displayRange(void)
{
 Serial.print ("Range: +/- "); 
 
 switch(accel.getRange())
 {
 case ADXL345_RANGE_16_G:
 Serial.print ("16 "); 
 break;
 case ADXL345_RANGE_8_G:
 Serial.print ("8 "); 
 break;
 case ADXL345_RANGE_4_G:
 Serial.print ("4 "); 
 break;
 case ADXL345_RANGE_2_G:
 Serial.print ("2 "); 
 break;
 default:
 Serial.print ("?? "); 
 break;
 } 
 Serial.println(" g"); 
}

void setup(void) 
{
 Serial.begin(9600);
 Serial.println("Accelerometer Test"); Serial.println("");
 
 /* Initialise the sensor */
 if(!accel.begin())
 {
 /* There was a problem detecting the ADXL345 ... check your connections */
 Serial.println("Ooops, no ADXL345 detected ... Check your wiring!");
 while(1);
 }

 /* Set the range to whatever is appropriate for your project */
 accel.setRange(ADXL345_RANGE_16_G);
 // displaySetRange(ADXL345_RANGE_8_G);
 // displaySetRange(ADXL345_RANGE_4_G);
 // displaySetRange(ADXL345_RANGE_2_G);
 
 /* Display some basic information on this sensor */
 displaySensorDetails();
 
 /* Display additional settings (outside the scope of sensor_t) */
 displayDataRate();
 displayRange();
 Serial.println("");
}

void loop(void) 
{
 /* Get a new sensor event */ 
 sensors_event_t event; 
 accel.getEvent(&event);
 
 /* Display the results (acceleration is measured in m/s^2) */
 Serial.print("X: "); Serial.print(event.acceleration.x); Serial.print(" ");
 Serial.print("Y: "); Serial.print(event.acceleration.y); Serial.print(" ");
 Serial.print("Z: "); Serial.print(event.acceleration.z); Serial.print(" ");Serial.println("m/s^2 ");
 delay(500);
}

 

Links

 

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