CodingPirates/microbit-micropython-cookbook
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@@ -25,6 +25,14 @@ this.authors()
love.badaboom() love.badaboom()
``` ```
## Editor of Choice
The official [Python online editor](https://python.microbit.org/v/2.0) does not need installation and can be used anywhere with Internet and Chrome web browser. Support Web-USB. It's ok to use, really.
Personally, I would perfer [Mu editor](https://codewith.mu/) for any beginners. It has code check, (limited) auto-complete and can automatically detect/upload code to your micro:bit.
If you have experiences with MicroPython with ESP8266/ESP32 or CircuitPython, you can consider [Thonny](https://thonny.org/) which allows you to access micro:bit's REPL directly without having to upload hex file.
## Some Lesser Known Facts ## Some Lesser Known Facts
Since both Python and MicroPython are interpreted languages, they eat a lot of memory. Also, the hex file generated by micro:bit Python editors are consisted of 2 parts: the MicroPython firmware (up to 248 KB) and user's script (up to only 8 KB). See [Firmware Hex File](https://microbit-micropython.readthedocs.io/en/latest/devguide/hexformat.html). Which means it's less likely to build bigger projects with micro:bit's MicroPython. Since both Python and MicroPython are interpreted languages, they eat a lot of memory. Also, the hex file generated by micro:bit Python editors are consisted of 2 parts: the MicroPython firmware (up to 248 KB) and user's script (up to only 8 KB). See [Firmware Hex File](https://microbit-micropython.readthedocs.io/en/latest/devguide/hexformat.html). Which means it's less likely to build bigger projects with micro:bit's MicroPython.
@@ -35,13 +43,9 @@ micro:bit's MicroPython is based on Python 3.4. Which means many built-in Python
Also, about how micro:bit get its own version of MicroPython: [The Story of MicroPython on the BBC micro:bit](http://ntoll.org/article/story-micropython-on-microbit) by Nicholas H. Tollervey, who also created the [Mu editor](https://codewith.mu/). Also, about how micro:bit get its own version of MicroPython: [The Story of MicroPython on the BBC micro:bit](http://ntoll.org/article/story-micropython-on-microbit) by Nicholas H. Tollervey, who also created the [Mu editor](https://codewith.mu/).
## Editor of Choice ## Recursion is Not Welcomed
The official [Python online editor](https://python.microbit.org/v/2.0) does not need installation and can be used anywhere with Internet and Chrome web browser. Support Web-USB. It's ok to use, really. Since micro:bit has very limited memory, the recursion depth is severely limited. Only [8 nested function calls or so](https://mail.python.org/pipermail/microbit/2016-February/000896.html) can be used without triggering RuntimeError.
Personally, I would perfer [Mu editor](https://codewith.mu/) for any beginners. It has code check, (limited) auto-complete and can automatically detect/upload code to your micro:bit.
If you have experiences with MicroPython with ESP8266/ESP32 or CircuitPython, you can consider [Thonny](https://thonny.org/) which allows you to access micro:bit's REPL directly without having to upload hex file.
## Why You Shouldn't Use * For Import ## Why You Shouldn't Use * For Import
@@ -76,25 +80,45 @@ gc.enable() # auto memory recycle
gc.collect() # force memory recycle gc.collect() # force memory recycle
``` ```
## Recursion is Not Welcomed
Since micro:bit has very limited memory, the recursion depth is severely limited. Only [8 nested function calls or so](https://mail.python.org/pipermail/microbit/2016-February/000896.html) can be used without triggering RuntimeError.
## Classic Blinky ## Classic Blinky
```python ```python
from microbit import display, sleep from microbit import display, Image, sleep
while True: while True:
display.set_pixel(0, 0, 9) display.show(Image.HEART)
sleep(1000) sleep(1000)
display.set_pixel(0, 0, 0) display.clear()
sleep(1000) sleep(1000)
``` ```
## Blinky LEDs Without Using Sleep
The two LEDs would blink at different intervals.
```python
from microbit import display
import utime
delay1, delay2 = 1000, 300
since1, since2 = utime.ticks_ms(), utime.ticks_ms()
while True:
now = utime.ticks_ms()
if utime.ticks_diff(now, since1) >= delay1:
display.set_pixel(0, 0, 9 if display.get_pixel(0, 0) == 0 else 0)
since1 = utime.ticks_ms()
if utime.ticks_diff(now, since2) >= delay2:
display.set_pixel(4, 4, 9 if display.get_pixel(4, 4) == 0 else 0)
since2 = utime.ticks_ms()
```
## Fill LED Display ## Fill LED Display
Light up every LEDs. Use fillScreen() as default. Light up every LEDs. You can use fillScreen() as default.
```python ```python
from microbit import display, Image, sleep from microbit import display, Image, sleep
@@ -121,6 +145,34 @@ while True:
sleep(50) sleep(50)
``` ```
## LED Bar Graph
A 25-level LED progress bar.
```python
from microbit import display, sleep
def plotBarGraph(value, maxValue, brightness=9):
bar = value / maxValue
valueArray = ((0.96, 0.88, 0.84, 0.92, 1.00),
(0.76, 0.68, 0.64, 0.72, 0.80),
(0.56, 0.48, 0.44, 0.52, 0.60),
(0.36, 0.28, 0.24, 0.32, 0.40),
(0.16, 0.08, 0.04, 0.12, 0.20))
for y in range(5):
for x in range(5):
display.set_pixel(x, y,
brightness if bar >= valueArray[y][x] else 0)
while True:
lightLevel = display.read_light_level()
plotBarGraph(lightLevel, 255) # or plotBarGraph(lightLevel, 255, 9)
sleep(50)
```
Since read_light_level() uses LEDs themselves as light sensors (see [this video](https://www.youtube.com/watch?v=TKhCr-dQMBY)), The LED screen would flicker a bit.
## A More Convenient Pin Class ## A More Convenient Pin Class
Make a Pin class to "rename" existing pin methods. Make a Pin class to "rename" existing pin methods.
@@ -163,7 +215,7 @@ while True:
## Another Version of Pin Class ## Another Version of Pin Class
Use **namedtuple** as a simple Pin class. Save more memory than regular class. Use **namedtuple** as a simple Pin class. Might save more memory than regular class.
```python ```python
from microbit import pin0, pin2, sleep from microbit import pin0, pin2, sleep
@@ -184,74 +236,18 @@ while True:
sleep(50) sleep(50)
``` ```
## Blinky Without Using Sleep ## Value Mapping
Translate a value in a range to its corresponding value in anoher range. Borrowed from [here](https://stackoverflow.com/questions/1969240/mapping-a-range-of-values-to-another).
```python ```python
from microbit import display def translate(value, leftMin, leftMax, rightMin, rightMax):
import utime leftSpan = leftMax - leftMin
rightSpan = rightMax - rightMin
delay = 1000 valueScaled = float(value - leftMin) / float(leftSpan)
since = utime.ticks_ms() return rightMin + (valueScaled * rightSpan)
while True:
now = utime.ticks_ms()
if utime.ticks_diff(now, since) >= delay:
display.set_pixel(0, 0, 9 if display.get_pixel(0, 0) == 0 else 0)
since = utime.ticks_ms()
``` ```
This method would be useful if you want to do severl things at different intervals:
```python
from microbit import display
import utime
delay1, delay2 = 1000, 300
since1, since2 = utime.ticks_ms(), utime.ticks_ms()
while True:
now = utime.ticks_ms()
if utime.ticks_diff(now, since1) >= delay1:
display.set_pixel(0, 0, 9 if display.get_pixel(0, 0) == 0 else 0)
since1 = utime.ticks_ms()
if utime.ticks_diff(now, since2) >= delay2:
display.set_pixel(4, 4, 9 if display.get_pixel(4, 4) == 0 else 0)
since2 = utime.ticks_ms()
```
## LED Bar Graph
A 25-level LED progress bar.
```python
from microbit import display, sleep
def plotBarGraph(value, maxValue, brightness=9):
bar = value / maxValue
valueArray = ((0.96, 0.88, 0.84, 0.92, 1.00),
(0.76, 0.68, 0.64, 0.72, 0.80),
(0.56, 0.48, 0.44, 0.52, 0.60),
(0.36, 0.28, 0.24, 0.32, 0.40),
(0.16, 0.08, 0.04, 0.12, 0.20))
for y in range(5):
for x in range(5):
display.set_pixel(x, y,
brightness if bar >= valueArray[y][x] else 0)
while True:
lightLevel = display.read_light_level()
plotBarGraph(lightLevel, 255) # or plotBarGraph(lightLevel, 255, 9)
sleep(50)
```
Since read_light_level() uses LEDs themselves as light sensors (see [this video](https://www.youtube.com/watch?v=TKhCr-dQMBY)), in this example a short delay is added, but the LED screen would still flicker a bit.
## Servo Control ## Servo Control
```python ```python
@@ -273,19 +269,8 @@ while True:
Do not use servos and buzzers at the same time. They require different PWM frequencies and most microcontrollers can only set one frequency accross all pins at a time. Do not use servos and buzzers at the same time. They require different PWM frequencies and most microcontrollers can only set one frequency accross all pins at a time.
Also: micro:bit's power output may just (barely) enough to power a single SG90 mini servo. External power supply recommended. Also: micro:bit's power output may just (barely) enough to power a single SG90 mini servo. External power supply is recommended.
## Value Mapping
Translate a value in a range to its corresponding value in anoher range. Borrowed from [here](https://stackoverflow.com/questions/1969240/mapping-a-range-of-values-to-another).
```python
def translate(value, leftMin, leftMax, rightMin, rightMax):
leftSpan = leftMax - leftMin
rightSpan = rightMax - rightMin
valueScaled = float(value - leftMin) / float(leftSpan)
return rightMin + (valueScaled * rightSpan)
```
## Get Pitch and Roll Degrees ## Get Pitch and Roll Degrees
@@ -314,7 +299,7 @@ while True:
print('Pitch:', rotationPitch(), ' / roll:', rotationRoll()) print('Pitch:', rotationPitch(), ' / roll:', rotationRoll())
sleep(100) sleep(100)
``` ```
## NeoPixel Rainbow/Rotation ## NeoPixel Rainbow/Rotation Effect
This code needs at least 3 LEDs in the NeoPixel chain. Of course, you can set a number (much) higher than actual LEDs to get smooth rainbow effects. This code needs at least 3 LEDs in the NeoPixel chain. Of course, you can set a number (much) higher than actual LEDs to get smooth rainbow effects.