onboard-micropython.md

On-Board Sensor Data Logging with MicroPython

This example uses the onboard sensors displayed below on the micro:bit:

---

Example: Accelerometer

Step 1: Import the Modules

Import the necessary module that are not preloaded with import log:

# Imports go at the top
from microbit import *
import log

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Step 2: Enable mirroring in Serial

This is not compulsory, but seeing the data being recorded shows that the code is working.

# Enable mirroring in serial
log.set_mirroring(True)

---

Step 3: Label the Column on the MY_DATA.HTM File

Set the name of the row labels on the log file.

# Label the accelerometer columns on the MY_DATA.HTM file
log.set_labels('x', 'y', 'z')

Step 4: Log the Data

Log the data every 10 millisecond sleep(10) in a while loop while with the log.add() method.

while True:
    # If button A is pressed log the accelerometer data
    if button_a.is_pressed():
        # Add rows to MY_DATA.HTM
        log.add({
            'x': accelerometer.get_x(),
            'y': accelerometer.get_y(),
            'z': accelerometer.get_z()
        })
    # If button B is pressed delete MY_DATA.HTM
    if button_b.is_pressed():
        # Delete MY_DATA.HTM
        log.delete()
    sleep(10)

Here is the complete commented code for the accelerometer.

# Imports go at the top
from microbit import *
import log

# Enable mirroring in serial
log.set_mirroring(True)

# Label the accelerometer columns on the MY_DATA.HTM file
log.set_labels('x', 'y', 'z')

# Code in a 'while True:' loop repeats forever
while True:
    # If button A is pressed log the accelerometer data
    if button_a.is_pressed():
        # Add rows to MY_DATA.HTM
        log.add({
            'x': accelerometer.get_x(),
            'y': accelerometer.get_y(),
            'z': accelerometer.get_z()
        })
    # If button B is pressed delete MY_DATA.HTM
    if button_b.is_pressed():
        # Delete MY_DATA.HTM
        log.delete()

    sleep(10)

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Code for Other On-Board Sensors

Change the labels in log.set_labels(). Make sure the names are strings in ' ' or " ". If there is more than one label, separate them with commas.

• accelerometer.get_x(): Get acceleration (x).
• accelerometer.get_y(): Get acceleration (y).
• accelerometer.get_y(): Get acceleration (z).
• compass.get_field_strength() : Get magnetic field strength (overall).
• compass.get_x(): Get magnetic field strength (x).
• compass.get_y(): Get magnetic field strength (y).
• compass.get_z(): Get magnetic field strength (z).
• microphone.sound_level(): Get sound level.
• read_light_level(): Get light level.
• temperature(): Get temperature.