Python Setup

The SPIKE App has a built-in Python editor; the hub runs MicroPython (a slim Python). This page covers the environment, your first Python program, and how it relates to Word Blocks.

Why upgrade to Python

	Word Blocks	Python
Getting started	fast	requires syntax
Loop speed	slower	fast (denser line-follow sampling = more stable)
Functions	My Blocks, no return values	real functions with returns
Math	painful nested blocks	one-line expressions
PID, data structures	barely	natural
Version control	binary project files	plain text, git-friendly

Suggested route: finish the Word Blocks track first (motors/sensors/control flow concepts) - everything transfers, only the notation changes.

New Python project

SPIKE App → New project → Python. Code editor on the left; the Console on the right shows print() output and error messages - a debugging tool Word Blocks never had.

This site uses the SPIKE App 3 API

LEGO rewrote the Python API in SPIKE App 3 (the import motor style). Many older tutorials online use the SPIKE 2 style (from spike import PrimeHub) - they are incompatible. On this site, the import motor / from hub import port style is the one to learn.

First program

import runloop
from hub import light_matrix, sound

async def main():
    await light_matrix.write("Hello")   # scrolls text; continues when done
    sound.beep(440, 300, 100)           # 440 Hz for 0.3 s
    print("done")                       # goes to the console

runloop.run(main())

Run it: the matrix scrolls "Hello", a beep plays, the console prints done.

The skeleton you must understand: async / await / runloop

SPIKE 3 Python is asynchronous. Any program that waits for an action to finish (which is nearly every robot program) uses this skeleton; purely synchronous scripts (just print, just lights) can skip it:

import runloop

async def main():
    ...   # your program goes here

runloop.run(main())

Three rules to memorize now (the advanced lesson explains the machinery):

1. The program body lives in async def main():.
2. Actions that "finish before continuing" (turn N degrees, finish scrolling text) get await in front.
3. The last line runloop.run(main()) starts everything.

await motor.run_for_degrees(...) = the blocking "run for degrees" block; without await it's like the "start motor" block - the motor still starts, the program just doesn't wait. Note this applies to LEGO's native API only: your own async functions do nothing without await - details in the advanced lesson.

print debugging

value = 42
print("reflection =", value)

Streaming sensor values to the console beats squinting at the 5x5 matrix:

import runloop, color_sensor
from hub import port

async def main():
    while True:
        print(color_sensor.reflection(port.C))
        await runloop.sleep_ms(100)

runloop.run(main())

Threshold calibration just got much more comfortable.

Exercises

1. Run the first program.
2. Deliberately misspell light_matrix, run, and read the console error top to bottom - reading errors is Python skill #1.
3. Use the loop above to print your sensor's black/white values; compare with your Word Blocks-era calibration.

Next lesson: API Basics - crash-course syntax plus the SPIKE module map.