Optimizing MicroPython Code: Strategies for Enhanced Performance

Identifying the Slowest Section of Code

Profiling is essential for identifying performance bottlenecks. While MicroPython may not support traditional profiling tools, you can use timing functions to measure execution time in milliseconds, microseconds, or CPU cycles. A practical approach is to use a @timed_function decorator to time function execution:

import time

def timed_function(f, *args, **kwargs):
    myname = str(f).split(' ')[1]
    def new_func(*args, **kwargs):
        t = time.ticks_us()
        result = f(*args, **kwargs)
        delta = time.ticks_diff(time.ticks_us(), t)
        print('Function {} Time = {:6.3f}ms'.format(myname, delta/1000))
        return result
    return new_func

Utilizing the const() Function

MicroPython features a const() declaration similar to #define in C. It replaces identifiers with numeric values during bytecode compilation, eliminating runtime dictionary lookups. The arguments must evaluate to an integer, like 0x100 or 1 << 8:

a = const(20)

Reducing and Shortening Variable Names

Minimize the number and length of variable names to improve clarity and potentially enhance performance. Consistently use short, descriptive identifiers.

Favoring Local Scope Over Global Scope

Avoid global variables when possible. Encapsulating variables within functions helps reduce scope-related errors and improves manageability.

Example:

from machine import Pin

# Inefficient
led = Pin(2, Pin.OUT)

def some_function():
    for x in range(100):
        led.value(not led.value())

some_function()

# Efficient

def some_function():
    led = Pin(2, Pin.OUT)
    for x in range(100):
        led.value(not led.value())

some_function()

Using Global Object References Locally

For better efficiency, reference global objects within the local scope of functions:

import time
from machine import Pin

def f():
    led = Pin(2, Pin.OUT)
    s = time.sleep
    while True:
        led.value(not led.value())
        s(1)

Avoiding * and ** Args in Functions

Using *args and **kwargs in function definitions increases lookup time. Opt for explicit parameter definitions when possible.

Compiling Programs to .mpy

Files in .mpy format decrease compilation times compared to .py files. For maximum efficiency, consider freezing your script into the firmware.

Pro Tip: Freezing scripts into firmware can significantly enhance your program's performance, making it more efficient and reliable for embedded applications.