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Tuesday 1 April 2025 8 versions

Short Introduction to Programming with Python

If you are new to programming with Python then you might have a look at the “Welcome To CircuitPython” guide by Adafruit. The chapter “How do I learn Python?” has links to guides for every level of experience.

Another guide “Getting Started with Raspberry Pi Pico and CircuitPython” is dedicated to programming “Pico” boards with CPy. The chapter “NeoPixel LEDs” is very helpful for this workshop.

These guides can also be downloaded from the assets directory.

Structure of a CircuitPython program

  1. import needed libraries (and methods)
  2. define your global variables (and constants)
  3. define (aka. develop) your own functions
  4. initialize all needed objects
  5. start the main loop

Control structures

Python does not use any explicit syntactic brackets ( like begin and end, or { and } ) to delimit compound statements.
That’s why indentation (usually by 4 spaces) is used to group statements.

Python does have most of the usual control structures.
But you need to terminate the ’test’ with a colon :.

 1# IF statement
 2if (a == b):
 3    x = y
 4elif (b == c):
 5    x = z
 6else:
 7    z = x +y
 8
 9# WHILE statement
10i = 0
11while (i < 10):
12    i += 1
13
14# FOR statement
15for j in range(10):
16    print(j)

Function definitions

The same is true for function definitions.
Put the name and all parameters onto the first line and terminate the line with a colon :.
Then you need to indent all statements of the function body.
The function definitions ends, when you outdent to the level of the def keyword.

1# Function defintion
2def fname(x, y, z):
3    return x * y * z
4
5print( fname(2, 3, 5) )

Data types

Python does have all the usual data types, like integers, floats and strings.
Some conversions are done implicitly. Others need to be carried out explicitly by calling a function.

1a, b = 5, 7
2x, y = 9.7, 6.5
3z = float( a + b )
4c = int( x / y )
5s = "my "
6t = " know"
7r = "ledge"
8print(z, c, s+t+r)

Data structures

The basic data structures of Python are lists, dictionaries, and tuples:

1# LISTS have indices that are integers and can be used as ARRAYS
2# delimiters are [ and ]
3a = [ 1, 2, 3, ]
4rgb = [ 0xff, 0xcc, 0xd8 ]
5b = [ 'a', 12, 3.14, [], rgb ]
6print( a[1], b[4] )

1# DICTIONARIES are similar to LISTS, 
2# except the indices are strings (or any other type)
3# delimiters are { and }
4word = {}
5word['en'] = 'book'
6word['de'] = 'buch'
7word['fr'] = 'livre'
8words = { 'one': 'eins', 'two': 'due', 'three': 'trois', }

1# TUPLES are an immutable sequence of values
2# delimiters are ( and )
3t = ( 1, 2, 3, 4, 5 )
4print( t[2] )

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