name = "John"
fav_color = 0x003366
body_temp = 98.65
fav_number = 123
print("name:%s color:%06x temp:%2.1f num:%d" % (name,fav_color,body_temp,fav_number))
# 'name:John color:ff3366 temp:98.6 num:123'

Formatting strings with f-strings

(This doesn't work on 'small' CircuitPythons like QTPy M0 due to the small amounts of flash memory on the board.)

name = "John"
fav_color = 0x003366
body_temp = 98.65
print(f"name:{name} color:{color:06x} temp:{body_temp:2.1f} num:{fav_number:%d}")
# 'name:John color:ff3366 temp:98.6 num:123'
# my_config.py
config = {
    "username": "Grogu Djarin",
    "password": "ig88rules",
    "secret_key": "3a3d9bfaf05835df69713c470427fe35"
}

# code.py
from my_config import config
print("secret:", config['secret_key'])
# 'secret: 3a3d9bfaf05835df69713c470427fe35'

Run different code.py on startup

Use microcontroller.nvm to store persistent state across resets or between boot.py and code.py, and declare that the first byte of nvm will be the startup_mode. Now if you create multiple code.py files (say) code1.py, code2.py, etc. you can switch between them based on startup_mode.

import time
import microcontroller
startup_mode = microcontroller.nvm[0]
if startup_mode == 1:
    import code1      # runs code in `code1.py`
if startup_mode == 2:
    import code2      # runs code in `code2.py`
# otherwise runs 'code.py`
while True:
    print("main code.py")
    time.sleep(1)

Note: in CircuitPyton 7+ you can use supervisor.set_next_code_file() to change which .py file is run on startup. This changes only what happens on reload, not hardware reset or powerup. Using it would look like:

import supervisor
supervisor.set_next_code_file('code_awesome.py')
# and then if you want to run it now, trigger a reload
supervisor.reload()

This guide was first published on Apr 02, 2022. It was last updated on Apr 02, 2022.

This page (Computery Tasks) was last updated on May 24, 2022.

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