On the back of the MatrixPortal is a triple-axis accelerometer that you can use to detect motion. (That's how our cool digital sand demo works!)
You can use this sensor in both CircuitPython and Arduino. After the library support is installed, you can then use the example code provided to get X, Y and Z acceleration values.
Arduino Usage
In Arduino, make sure to install our LIS3DH library, our guide for the individual sensor covers all that here
You can then load up this example
However, before you upload it - change this line:
if (! lis.begin(0x18)) { // change this to 0x19 for alternative i2c address
to:
if (! lis.begin(0x19)) { // change this to 0x19 for alternative i2c address
This will change the library to use the alternate address 0x19 of the accelerometer instead of the default 0x18!
// Basic demo for accelerometer readings from Adafruit LIS3DH
#include <Wire.h>
#include <SPI.h>
#include <Adafruit_LIS3DH.h>
#include <Adafruit_Sensor.h>
// Used for software SPI
#define LIS3DH_CLK 13
#define LIS3DH_MISO 12
#define LIS3DH_MOSI 11
// Used for hardware & software SPI
#define LIS3DH_CS 10
// software SPI
//Adafruit_LIS3DH lis = Adafruit_LIS3DH(LIS3DH_CS, LIS3DH_MOSI, LIS3DH_MISO, LIS3DH_CLK);
// hardware SPI
//Adafruit_LIS3DH lis = Adafruit_LIS3DH(LIS3DH_CS);
// I2C
Adafruit_LIS3DH lis = Adafruit_LIS3DH();
void setup(void) {
Serial.begin(115200);
while (!Serial) delay(10); // will pause Zero, Leonardo, etc until serial console opens
Serial.println("LIS3DH test!");
if (! lis.begin(0x18)) { // change this to 0x19 for alternative i2c address
Serial.println("Couldnt start");
while (1) yield();
}
Serial.println("LIS3DH found!");
// lis.setRange(LIS3DH_RANGE_4_G); // 2, 4, 8 or 16 G!
Serial.print("Range = "); Serial.print(2 << lis.getRange());
Serial.println("G");
// lis.setDataRate(LIS3DH_DATARATE_50_HZ);
Serial.print("Data rate set to: ");
switch (lis.getDataRate()) {
case LIS3DH_DATARATE_1_HZ: Serial.println("1 Hz"); break;
case LIS3DH_DATARATE_10_HZ: Serial.println("10 Hz"); break;
case LIS3DH_DATARATE_25_HZ: Serial.println("25 Hz"); break;
case LIS3DH_DATARATE_50_HZ: Serial.println("50 Hz"); break;
case LIS3DH_DATARATE_100_HZ: Serial.println("100 Hz"); break;
case LIS3DH_DATARATE_200_HZ: Serial.println("200 Hz"); break;
case LIS3DH_DATARATE_400_HZ: Serial.println("400 Hz"); break;
case LIS3DH_DATARATE_POWERDOWN: Serial.println("Powered Down"); break;
case LIS3DH_DATARATE_LOWPOWER_5KHZ: Serial.println("5 Khz Low Power"); break;
case LIS3DH_DATARATE_LOWPOWER_1K6HZ: Serial.println("16 Khz Low Power"); break;
}
}
void loop() {
lis.read(); // get X Y and Z data at once
// Then print out the raw data
Serial.print("X: "); Serial.print(lis.x);
Serial.print(" \tY: "); Serial.print(lis.y);
Serial.print(" \tZ: "); Serial.print(lis.z);
/* Or....get a new sensor event, normalized */
sensors_event_t event;
lis.getEvent(&event);
/* Display the results (acceleration is measured in m/s^2) */
Serial.print("\t\tX: "); Serial.print(event.acceleration.x);
Serial.print(" \tY: "); Serial.print(event.acceleration.y);
Serial.print(" \tZ: "); Serial.print(event.acceleration.z);
Serial.println(" m/s^2 ");
Serial.println();
delay(200);
}
CircuitPython Usage
To use with CircuitPython, you need to first install a few libraries, into the lib folder on your CIRCUITPY drive. Then you need to update code.py with the example script.
Thankfully, we can do this in one go. In the example below, click the Download Project Bundle button below to download the necessary libraries and the code.py file in a zip file. Extract the contents of the zip file, open the directory examples/ and then click on the directory that matches the version of CircuitPython you're using and copy the contents of that directory to your CIRCUITPY drive.
Your CIRCUITPY drive should now look similar to the following image:
# SPDX-FileCopyrightText: 2021 ladyada for Adafruit Industries
# SPDX-License-Identifier: MIT
import time
import board
import busio
import adafruit_lis3dh
# Hardware I2C setup. Use the CircuitPlayground built-in accelerometer if available;
# otherwise check I2C pins.
if hasattr(board, "ACCELEROMETER_SCL"):
i2c = busio.I2C(board.ACCELEROMETER_SCL, board.ACCELEROMETER_SDA)
lis3dh = adafruit_lis3dh.LIS3DH_I2C(i2c, address=0x19)
else:
i2c = board.I2C() # uses board.SCL and board.SDA
# i2c = board.STEMMA_I2C() # For using the built-in STEMMA QT connector on a microcontroller
lis3dh = adafruit_lis3dh.LIS3DH_I2C(i2c)
# Hardware SPI setup:
# spi = board.SPI()
# cs = digitalio.DigitalInOut(board.D5) # Set to correct CS pin!
# lis3dh = adafruit_lis3dh.LIS3DH_SPI(spi, cs)
# PyGamer or MatrixPortal I2C Setup:
# i2c = board.I2C() # uses board.SCL and board.SDA
# lis3dh = adafruit_lis3dh.LIS3DH_I2C(i2c, address=0x19)
# Set range of accelerometer (can be RANGE_2_G, RANGE_4_G, RANGE_8_G or RANGE_16_G).
lis3dh.range = adafruit_lis3dh.RANGE_2_G
# Loop forever printing accelerometer values
while True:
# Read accelerometer values (in m / s ^ 2). Returns a 3-tuple of x, y,
# z axis values. Divide them by 9.806 to convert to Gs.
x, y, z = [
value / adafruit_lis3dh.STANDARD_GRAVITY for value in lis3dh.acceleration
]
print("x = %0.3f G, y = %0.3f G, z = %0.3f G" % (x, y, z))
# Small delay to keep things responsive but give time for interrupt processing.
time.sleep(0.1)
Before you save, however, you must tell the example where to find the sensor!
Remove these lines:
# Hardware I2C setup. Use the CircuitPlayground built-in accelerometer if available;
# otherwise check I2C pins.
if hasattr(board, "ACCELEROMETER_SCL"):
i2c = busio.I2C(board.ACCELEROMETER_SCL, board.ACCELEROMETER_SDA)
lis3dh = adafruit_lis3dh.LIS3DH_I2C(i2c, address=0x19)
else:
i2c = board.I2C() # uses board.SCL and board.SDA
# i2c = board.STEMMA_I2C() # For using the built-in STEMMA QT connector on a microcontroller
lis3dh = adafruit_lis3dh.LIS3DH_I2C(i2c)
And 'uncomment' these lines:
# PyGamer or MatrixPortal I2C Setup: # i2c = board.I2C() # uses board.SCL and board.SDA # lis3dh = adafruit_lis3dh.LIS3DH_I2C(i2c, address=0x19)
So they look like this:
# PyGamer or MatrixPortal I2C Setup: i2c = board.I2C() # uses board.SCL and board.SDA lis3dh = adafruit_lis3dh.LIS3DH_I2C(i2c, address=0x19)
Now you can save, and check the REPL for acceleration data!
