micropython-BPIBIT: A MicroPython ESP32 Module for BPI:bit/Web:bit

This is a MicroPython module designed for the BPI:bit/Web:bit, using BBC micro:bit pin numbers and provide various easy-to-use functions.

This module only works for MicroPython firmware v1.17 for ESP32. Since v1.18 the PWM frequency range has changed so the note playing would be mostly useless.

Install Module

Upload these onto your board:

• BPIBIT.py
• mpu9250.py
• mpu6500.py
• ak8963.py

The library for the onboard MPU-9250 is from this repo: MicroPython MPU-9250 (MPU-6500 + AK8963) I2C driver. Without this driver the BPIBIT module still works, but all the accelerometer/gyroscope/compass functions would not work and only return None.

Blinky LED

Blink the tiny red LED behind the board:

import BPIBIT

while True:
    BPIBIT.digitalWritePin('BUILTIN_LED', 1)
    BPIBIT.pause(500)
    BPIBIT.digitalWritePin('BUILTIN_LED', 0)
    BPIBIT.pause(500)  # or BPIBIT.pauseMicros(500000)

System Running Time

import BPIBIT

while True:
    print(BPIBIT.runningTime())
    # print(BPIBIT.runningTimeMicros())
    BPIBIT.pause(100)

Read/Write GPIOs

result = BPIBIT.digitalReadPin(pin=2)  # read digital signal of pin 2
result = BPIBIT.analogReadPin(pin=2)  # read analog signal of pin 2
BPIBIT.digitalWritePin(pin=2, value=1)  # write digital signal to pin 2
BPIBIT.analogWritePin(pin=2, value=1023)  # write analog signal (PWM) to pin 2

All ESP32 pins in this module are remapped to micro:bit pin numbers. For example, pin 2 is actually pin 33 on ESP32. It's easier to use micro:bit accessories this way.

All digital pins can be used to write analog signals; on the other hand, only pin 1 and 2 can be used to read analog signals (0-1023).

Servo Control

import BPIBIT

while True:
    BPIBIT.servoWritePin(pin=2, degree=0)
    BPIBIT.pause(1000)
    BPIBIT.servoWritePin(pin=2, degree=180)
    BPIBIT.pause(1000)

Buttons/Touchpads

import BPIBIT

while True:
    print(BPIBIT.onButtonPressed(button='A'))  # if button A is being pressed
    BPIBIT.pause(100)

Parameter "button" can be 'A', 'B' or 'AB' (both).

ESP32 also supports capacitive touch; on BPI:bit pin 1, 2, 3, 6, 7, 11 are available. However, without external touchpads only Pin 1 and 2 are large enough to be touched by finger, and Pin 0 (GPIO 25) does not support capacitive touch.

import BPIBIT

while True:
    print(BPIBIT.pinIsTouched(pin=2))  # set pin 2 as touchpad and return pressing status
    BPIBIT.pause(100)

Buzzer and Tone

BPIBIT.analogPitch(freq=1047, delay=0)  # set buzzer to play 1047 Hz, no stop
BPIBIT.playTone(note='C6', delay=500)  # set buzzer to play note C6 (1047 Hz) for 500 ms
BPIBIT.rest(500)  # rest 500 ms
BPIBIT.noTone()  # turn off buzzer

The module has a built-in note library ranged from C3 to C7. C3 sharp/D3 flap is written as 'C3D3', and so on. If you input a wrong note, no sound will be played for it.

Below is a short music example:

import BPIBIT

tempo = 400

BPIBIT.playTone('D4', tempo)
BPIBIT.playTone('G4', tempo * 2)
BPIBIT.playTone('A4B4', tempo)
BPIBIT.playTone('D5', tempo * 2)
BPIBIT.playTone('G5', tempo)
BPIBIT.playTone('A5B5', tempo * 1.5)
BPIBIT.playTone('A5', tempo * 0.5)
BPIBIT.playTone('G5', tempo)
BPIBIT.playTone('A5', tempo * 2)
BPIBIT.playTone('D5', tempo)
BPIBIT.playTone('D5', tempo * 1.5)
BPIBIT.playTone('C5', tempo * 0.5)
BPIBIT.playTone('E5', tempo)
BPIBIT.playTone('D5', tempo * 1.5)
BPIBIT.playTone('C5', tempo * 0.5)
BPIBIT.playTone('E5', tempo)
BPIBIT.playTone('D5', tempo * 4)
BPIBIT.rest(tempo)
BPIBIT.playTone('D4', tempo)
BPIBIT.playTone('G4', tempo * 2)
BPIBIT.playTone('A4B4', tempo)
BPIBIT.playTone('D5', tempo * 2)
BPIBIT.playTone('F5', tempo)
BPIBIT.playTone('G5A5', tempo * 1.5)
BPIBIT.playTone('G5', tempo * 0.5)
BPIBIT.playTone('F5', tempo)
BPIBIT.playTone('G5', tempo * 2)
BPIBIT.playTone('G4', tempo)
BPIBIT.playTone('G4', tempo * 1.5)
BPIBIT.playTone('F4G4', tempo * 0.5)
BPIBIT.playTone('A4', tempo)
BPIBIT.playTone('G4', tempo * 1.5)
BPIBIT.playTone('F4G4', tempo * 0.5)
BPIBIT.playTone('A4B4', tempo)
BPIBIT.playTone('G4', tempo * 4)
BPIBIT.noTone()

Read Light Level

import BPIBIT

while True:
    print(BPIBIT.lightLevel())  # returns 0-1023
    BPIBIT.pause(100)

BPIBIT.lightLevel() returns the average value of the two LDRs. You can read either by using BPIBIT.lightLevelL() or BPIBIT.lightLevelR().

Read Temperature

import BPIBIT

while True:
    c = BPIBIT.temperature()  # read temperature in Celsius
    f = c * 9 / 5 + 32  # convert to Fahrenheit
    print('c =', c, '/ f =', f)
    BPIBIT.pause(100)

The temperature sensor is analog so the reading may not be very accurate and would be affected by the board itself.

BPIBIT.temperatureRaw() would return the analog value of the thermistor (0-1023).

Acceleration, Gyroscope and Compass

import BPIBIT

while True:
    pitch = BPIBIT.rotationPitch()
    roll = BPIBIT.rotationRoll()
    heading = BPIBIT.compassHeading()
    print('Pitch =', pitch, '/ roll =', roll, '/ heading = ', heading)
    BPIBIT.pause(100)

These function would only return None if the MPU-9250 cannot be initialized.

value = BPIBIT.acceleration('x')  # get acceleration on x axis
value = BPIBIT.rotationPitch()  # get pitch angles
value = BPIBIT.rotationRoll()  # get roll angles
value = BPIBIT.gyroscope('y')  # get angular velocity on x axis
value = BPIBIT.magneticForce('z')  # get magnetic force on x axis
value = BPIBIT.compassHeading()  # get compass heading
BPIBIT.calibrateCompass()  # calibrate compass

The axis parameter can be 'x', 'y', 'z' or '' (absolute value of all axis combined).

Compass calibration takes 15 seconds. Turn your BPI:bit around at all directions and away from other magnetic fields ifpossible.

5x5 NeoPixel LED Display

BPIBIT.led(0, (64, 64, 0))  # set LED 0 to (64, 64, 0)
BPIBIT.ledAll((0, 32, 32))  # set all LEDs to (0, 32, 32)
BPIBIT.ledCode(5, code='R')  # set LED 5 to red
BPIBIT.ledCodeAll(code='G')  # set all LEDs to green
BPIBIT.ledOff()  #Turn off all LEDs

The LED indexes are 0 (right-bottom corner) to 24 (left-top corner). Parameter 'code' are pre-defined color codes:

• 'W' = white
• 'R' = red
• 'O' = orange
• 'Y' = yellow
• 'G' = green
• 'T' = turquoise
• 'C' = cyan
• 'B' = blue
• 'V' = violet
• 'P' = Purple
• '*' (asterisk) = black (off)

When using color codes, the brightness are reduced to protect the NeoPixels (so they won't be easily damaged). If you really want to light them up, use BPIBIT.led() and BPIBIT.ledAll() to set the raw value (each color 0~255).

Display LED Pattern

import BPIBIT

ledArray = ['B', 'B', 'B', 'R', 'R',
            'B', 'W', 'B', 'R', 'R',
            'B', 'B', 'B', 'R', 'R',
            'R', 'R', 'R', 'R', 'R',
            'R', 'R', 'R', 'R', 'R']
            
BPIBIT.ledCodeArray(array=ledArray)

LED Progress Bar Graph

import BPIBIT

while True:
    v = BPIBIT.lightLevel()
    BPIBIT.plotBarGraph(value=v, maxValue=1023, code='Y')
    BPIBIT.pause(100)

Scroll Text

import BPIBIT

colors = ['W', 'R', 'O', 'Y', 'G', 'T', 'C', 'B', 'V', 'P']

while True:
    for c in colors:
        BPIBIT.scrollText('Hello BPI:bit', delay=100, code=c)  # will wait until scrolling is over
        BPIBIT.pause(500)

I2C

# get software I2C
i2c = BPIBIT.getI2C(scl=19, sda=20)

SPI

# get software SPI
spi = BPIBIT.getSPI(sck=13, miso=14, mosi=15, baudrate=100000, polarity=1, phase=0)

# hardware SPI 1: sck=7, miso=6, mosi=3
hspi = BPIBIT.getHSPI(baudrate=10000000, polarity=1, phase=0)

# hardware SPI 2: sck=13, miso=14, mosi=15
vspi = BPIBIT.getHSPI(baudrate=10000000, polarity=1, phase=0)

Garbage Collection

The module enables auto memory garbage collection on import.