Accel Unit

This is the driver library of Accel Unit, which is used to obtain data from the acceleration sensor and support motion detection.

Support the following products:

UiFlow2 Example

get accel value

Open the stickcplus2_unit_accel_example.m5f2 project in UiFlow2.

This example gets the acceleration value of the Accel Unit and displays it on the screen.

UiFlow2 Code Block:

Example output:

None

MicroPython Example

get accel value

This example gets the acceleration value of the Accel Unit and displays it on the screen.

MicroPython Code Block:

# SPDX-FileCopyrightText: 2024 M5Stack Technology CO LTD
#
# SPDX-License-Identifier: MIT

import os, sys, io
import M5
from M5 import *
from hardware import *
from unit import AccelUnit


label0 = None
label1 = None
label2 = None
title0 = None
label3 = None
label4 = None
label5 = None
i2c0 = None
accel_0 = None


acc = None


def setup():
    global label0, label1, label2, title0, label3, label4, label5, i2c0, accel_0, acc

    M5.begin()
    label0 = Widgets.Label("x:", 4, 48, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)
    label1 = Widgets.Label("y:", 4, 88, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)
    label2 = Widgets.Label("z:", 4, 128, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)
    title0 = Widgets.Title("ACCEL UNIT", 3, 0xFFFFFF, 0x0000FF, Widgets.FONTS.DejaVu18)
    label3 = Widgets.Label("label3", 24, 48, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)
    label4 = Widgets.Label("label4", 24, 88, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)
    label5 = Widgets.Label("label5", 24, 128, 1.0, 0xFFFFFF, 0x222222, Widgets.FONTS.DejaVu18)

    i2c0 = I2C(0, scl=Pin(33), sda=Pin(32), freq=100000)
    accel_0 = AccelUnit(i2c0, 0x53)


def loop():
    global label0, label1, label2, title0, label3, label4, label5, i2c0, accel_0, acc
    M5.update()
    acc = accel_0.get_accel()
    label3.setText(str(acc[0]))
    label4.setText(str(acc[1]))
    label5.setText(str(acc[2]))


if __name__ == "__main__":
    try:
        setup()
        while True:
            loop()
    except (Exception, KeyboardInterrupt) as e:
        try:
            from utility import print_error_msg

            print_error_msg(e)
        except ImportError:
            print("please update to latest firmware")

Example output:

None

API

AccelUnit

class unit.accel.AccelUnit(i2c, address=83)

Bases: ADXL345

Create an AccelUnit object.

Parameters:

i2c (I2C) – The I2C bus the Accel Unit is connected to.
address (int) – The I2C address of the device. Default is 0x53.

UiFlow2 Code Block:

MicroPython Code Block:

from hardware import I2C
from unit import AccelUnit

acceli2c0 = I2C(0, scl=Pin(1), sda=Pin(2), freq=100000)
accel_0 = AccelUnit(i2c0)

disable_freefall_detection()

Disable freefall detection.

UiFlow2 Code Block:

MicroPython Code Block:

accel_0.disable_freefall_detection()

Return type:: None

disable_motion_detection()

Disable motion detection.

UiFlow2 Code Block:

MicroPython Code Block:

accel_0.disable_motion_detection()

Return type:: None

disable_tap_detection()

Disable tap detection.

UiFlow2 Code Block:

MicroPython Code Block:

accel_0.disable_tap_detection()

Return type:: None

enable_freefall_detection(*, threshold=10, time=25)

Freefall detection parameters:

Parameters:

threshold (int) – The value that acceleration on all axes must be under to register as dropped. The scale factor is 62.5 mg/LSB.
time (int) – The amount of time that acceleration on all axes must be less than threshold to register as dropped. The scale factor is 5 ms/LSB. Values between 100 ms and 350 ms (20 to 70) are recommended.

Return type:

None

If you wish to set them yourself rather than using the defaults, you must use keyword arguments:

accelerometer.enable_freefall_detection(time=30)

UiFlow2 Code Block:

MicroPython Code Block:

accel_0.enable_freefall_detection()

enable_motion_detection(*, threshold=18)

The activity detection parameters.

Parameters:: threshold (int) – The value that acceleration on any axis must exceed to register as active. The scale factor is 62.5 mg/LSB.
Return type:: None

If you wish to set them yourself rather than using the defaults, you must use keyword arguments:

accelerometer.enable_motion_detection(threshold=20)

UiFlow2 Code Block:

MicroPython Code Block:

accel_0.enable_motion_detection(threshold=18)

enable_tap_detection(*, threshold=20, duration=50, latency=20, window=255)

The tap detection parameters.

Parameters:

tap_count (int) – 1 to detect only single taps, and 2 to detect only double taps.
threshold (int) – A threshold for the tap detection. The scale factor is 62.5 mg/LSB The higher the value the less sensitive the detection.
duration (int) – This caps the duration of the impulse above threshold. Anything above duration won’t register as a tap. The scale factor is 625 µs/LSB.
latency (int) – (double tap only) The length of time after the initial impulse falls below threshold to start the window looking for a second impulse. The scale factor is 1.25 ms/LSB.
window (int) – (double tap only) The length of the window in which to look for a second tap. The scale factor is 1.25 ms/LSB.

Return type:

None

If you wish to set them yourself rather than using the defaults, you must use keyword arguments:

accelerometer.enable_tap_detection(duration=30, threshold=25)

UiFlow2 Code Block:

MicroPython Code Block:

accel_0.enable_tap_detection(tap_count=1, threshold=20, duration=50, latency=20, window=255)

get_accel()

The x, y, z acceleration values returned in a 3-tuple in \(m / s ^ 2\).

Returns:: x, y, z acceleration values in \(m / s ^ 2\).
Return type:: tuple[float, float, float]

UiFlow2 Code Block:

MicroPython Code Block:

accel_0.get_accel()

get_data_rate()

Get the data rate of the sensor.

Returns:: The data rate of the sensor.
Return type:: int

UiFlow2 Code Block:

MicroPython Code Block:

accel_0.get_data_rate()

get_range()

Get the measurement range of the sensor.

Returns:: The measurement range of the sensor.
Return type:: int

UiFlow2 Code Block:

MicroPython Code Block:

accel_0.get_range()

is_freefall()

Returns True if freefall has been detected.

Returns:: True if freefall has been detected.
Return type:: bool

UiFlow2 Code Block:

MicroPython Code Block:

accel_0.is_freefall()

is_motion()

Returns True if motion has been detected.

Returns:: True if motion has been detected.
Return type:: bool

UiFlow2 Code Block:

MicroPython Code Block:

accel_0.is_motion()

is_tap()

Returns True if a tap has been detected.

Returns:: True if a tap has been detected.
Return type:: bool

UiFlow2 Code Block:

MicroPython Code Block:

accel_0.is_tap()

set_data_rate(rate)

Set the data rate of the sensor.

Parameters:: rate (int) – The data rate of the sensor.
Return type:: None

UiFlow2 Code Block:

MicroPython Code Block:

accel_0.set_data_rate(accel_0.RATE_3200_HZ)

set_range(range)

The measurement range of the sensor.

Parameters:: range (int) – The measurement range of the sensor.
Return type:: None

UiFlow2 Code Block:

MicroPython Code Block:

accel_0.set_range(accel_0.RANGE_2_G)

ADXL345

class unit.accel.ADXL345(i2c, address=micropython.const)

Bases: object

Driver for the ADXL345 3 axis accelerometer.

Parameters:

i2c (I2C) – The I2C bus the ADXL345 is connected to.
address (int) – The I2C device address for the sensor. Default is 0x53.

Quickstart: Importing and using the device

Here is an example of using the ADXL345 class. First you will need to import the libraries to use the sensor:
import machine
import adxl34x
Once this is done you can define your I2C object and define your sensor object:
i2c = machine.I2C(0)  # uses board default SDA and SCL pins
accelerometer = adxl34x.ADXL343(i2c)
Now you have access to the acceleration attribute:
acceleration = accelerometer.acceleration

property acceleration: tuple[int, int, int]: The x, y, z acceleration values returned in a 3-tuple in \(m / s ^ 2\).

property data_rate: int: The data rate of the sensor.

disable_freefall_detection()

Disable freefall detection.

Return type:: None

disable_motion_detection()

Disable motion detection.

Return type:: None

disable_tap_detection()

Disable tap detection.

Return type:: None

enable_freefall_detection(*, threshold=10, time=25)

Freefall detection parameters:

Parameters:

threshold (int) – The value that acceleration on all axes must be under to register as dropped. The scale factor is 62.5 mg/LSB.
time (int) – The amount of time that acceleration on all axes must be less than threshold to register as dropped. The scale factor is 5 ms/LSB. Values between 100 ms and 350 ms (20 to 70) are recommended.

Return type:

None

If you wish to set them yourself rather than using the defaults, you must use keyword arguments:

accelerometer.enable_freefall_detection(time=30)

enable_motion_detection(*, threshold=18)

The activity detection parameters.

Parameters:: threshold (int) – The value that acceleration on any axis must exceed to register as active. The scale factor is 62.5 mg/LSB.

If you wish to set them yourself rather than using the defaults, you must use keyword arguments:

accelerometer.enable_motion_detection(threshold=20)

enable_tap_detection(*, tap_count=1, threshold=20, duration=50, latency=20, window=255)

The tap detection parameters.

Parameters:

tap_count (int) – 1 to detect only single taps, and 2 to detect only double taps.
threshold (int) – A threshold for the tap detection. The scale factor is 62.5 mg/LSB The higher the value the less sensitive the detection.
duration (int) – This caps the duration of the impulse above threshold. Anything above duration won’t register as a tap. The scale factor is 625 µs/LSB.
latency (int) – (double tap only) The length of time after the initial impulse falls below threshold to start the window looking for a second impulse. The scale factor is 1.25 ms/LSB.
window (int) – (double tap only) The length of the window in which to look for a second tap. The scale factor is 1.25 ms/LSB.

If you wish to set them yourself rather than using the defaults, you must use keyword arguments:

accelerometer.enable_tap_detection(duration=30, threshold=25)

property events: dict[str, bool]

events will return a dictionary with a key for each event type that has been enabled.

The possible keys are:

Key	Description
`tap`	True if a tap was detected recently. Whether it’s looking for a single or double tap is determined by the tap param of enable_tap_detection.
`motion`	True if the sensor has seen acceleration above the threshold set with enable_motion_detection.
`freefall`	True if the sensor was in freefall. Parameters are set when enabled with enable_freefall_detection.

property offset: tuple[int, int, int]

The x, y, z offsets as a tuple of raw count values.

See offset_calibration example for usage.

property range: int: The measurement range of the sensor.

property raw_x: int: The raw x value.

property raw_y: int: The raw y value.

property raw_z: int: The raw z value.