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Update README.md
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Alan Wang
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README.md
169
README.md
@@ -25,6 +25,14 @@ this.authors()
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love.badaboom()
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```
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## Editor of Choice
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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.
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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.
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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.
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## Some Lesser Known Facts
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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.
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@@ -35,13 +43,9 @@ micro:bit's MicroPython is based on Python 3.4. Which means many built-in Python
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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/).
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## Editor of Choice
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## Recursion is Not Welcomed
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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.
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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.
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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.
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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.
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## Why You Shouldn't Use * For Import
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@@ -76,25 +80,45 @@ gc.enable() # auto memory recycle
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gc.collect() # force memory recycle
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```
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## Recursion is Not Welcomed
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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.
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## Classic Blinky
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```python
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from microbit import display, sleep
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from microbit import display, Image, sleep
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while True:
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display.set_pixel(0, 0, 9)
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display.show(Image.HEART)
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sleep(1000)
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display.set_pixel(0, 0, 0)
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display.clear()
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sleep(1000)
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```
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## Blinky LEDs Without Using Sleep
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The two LEDs would blink at different intervals.
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```python
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from microbit import display
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import utime
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delay1, delay2 = 1000, 300
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since1, since2 = utime.ticks_ms(), utime.ticks_ms()
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while True:
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now = utime.ticks_ms()
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if utime.ticks_diff(now, since1) >= delay1:
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display.set_pixel(0, 0, 9 if display.get_pixel(0, 0) == 0 else 0)
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since1 = utime.ticks_ms()
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if utime.ticks_diff(now, since2) >= delay2:
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display.set_pixel(4, 4, 9 if display.get_pixel(4, 4) == 0 else 0)
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since2 = utime.ticks_ms()
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```
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## Fill LED Display
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Light up every LEDs. Use fillScreen() as default.
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Light up every LEDs. You can use fillScreen() as default.
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```python
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from microbit import display, Image, sleep
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@@ -121,6 +145,34 @@ while True:
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sleep(50)
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```
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## LED Bar Graph
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A 25-level LED progress bar.
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```python
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from microbit import display, sleep
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def plotBarGraph(value, maxValue, brightness=9):
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bar = value / maxValue
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valueArray = ((0.96, 0.88, 0.84, 0.92, 1.00),
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(0.76, 0.68, 0.64, 0.72, 0.80),
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(0.56, 0.48, 0.44, 0.52, 0.60),
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(0.36, 0.28, 0.24, 0.32, 0.40),
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(0.16, 0.08, 0.04, 0.12, 0.20))
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for y in range(5):
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for x in range(5):
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display.set_pixel(x, y,
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brightness if bar >= valueArray[y][x] else 0)
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while True:
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lightLevel = display.read_light_level()
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plotBarGraph(lightLevel, 255) # or plotBarGraph(lightLevel, 255, 9)
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sleep(50)
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```
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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.
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## A More Convenient Pin Class
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Make a Pin class to "rename" existing pin methods.
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@@ -163,7 +215,7 @@ while True:
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## Another Version of Pin Class
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Use **namedtuple** as a simple Pin class. Save more memory than regular class.
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Use **namedtuple** as a simple Pin class. Might save more memory than regular class.
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```python
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from microbit import pin0, pin2, sleep
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@@ -184,74 +236,18 @@ while True:
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sleep(50)
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```
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## Blinky Without Using Sleep
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## Value Mapping
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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).
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```python
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from microbit import display
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import utime
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delay = 1000
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since = utime.ticks_ms()
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while True:
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now = utime.ticks_ms()
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if utime.ticks_diff(now, since) >= delay:
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display.set_pixel(0, 0, 9 if display.get_pixel(0, 0) == 0 else 0)
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since = utime.ticks_ms()
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def translate(value, leftMin, leftMax, rightMin, rightMax):
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leftSpan = leftMax - leftMin
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rightSpan = rightMax - rightMin
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valueScaled = float(value - leftMin) / float(leftSpan)
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return rightMin + (valueScaled * rightSpan)
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```
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This method would be useful if you want to do severl things at different intervals:
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```python
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from microbit import display
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import utime
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delay1, delay2 = 1000, 300
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since1, since2 = utime.ticks_ms(), utime.ticks_ms()
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while True:
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now = utime.ticks_ms()
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if utime.ticks_diff(now, since1) >= delay1:
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display.set_pixel(0, 0, 9 if display.get_pixel(0, 0) == 0 else 0)
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since1 = utime.ticks_ms()
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if utime.ticks_diff(now, since2) >= delay2:
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display.set_pixel(4, 4, 9 if display.get_pixel(4, 4) == 0 else 0)
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since2 = utime.ticks_ms()
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```
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## LED Bar Graph
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A 25-level LED progress bar.
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```python
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from microbit import display, sleep
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def plotBarGraph(value, maxValue, brightness=9):
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bar = value / maxValue
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valueArray = ((0.96, 0.88, 0.84, 0.92, 1.00),
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(0.76, 0.68, 0.64, 0.72, 0.80),
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(0.56, 0.48, 0.44, 0.52, 0.60),
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(0.36, 0.28, 0.24, 0.32, 0.40),
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(0.16, 0.08, 0.04, 0.12, 0.20))
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for y in range(5):
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for x in range(5):
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display.set_pixel(x, y,
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brightness if bar >= valueArray[y][x] else 0)
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while True:
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lightLevel = display.read_light_level()
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plotBarGraph(lightLevel, 255) # or plotBarGraph(lightLevel, 255, 9)
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sleep(50)
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```
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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.
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## Servo Control
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```python
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@@ -273,19 +269,8 @@ while True:
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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.
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Also: micro:bit's power output may just (barely) enough to power a single SG90 mini servo. External power supply recommended.
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Also: micro:bit's power output may just (barely) enough to power a single SG90 mini servo. External power supply is recommended.
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## Value Mapping
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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).
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```python
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def translate(value, leftMin, leftMax, rightMin, rightMax):
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leftSpan = leftMax - leftMin
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rightSpan = rightMax - rightMin
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valueScaled = float(value - leftMin) / float(leftSpan)
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return rightMin + (valueScaled * rightSpan)
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```
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## Get Pitch and Roll Degrees
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@@ -314,7 +299,7 @@ while True:
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print('Pitch:', rotationPitch(), ' / roll:', rotationRoll())
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sleep(100)
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```
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## NeoPixel Rainbow/Rotation
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## NeoPixel Rainbow/Rotation Effect
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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.
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