CircuitPython works with WiFi-capable boards to enable you to make projects that have network connectivity. This means working with various passwords and API keys. As of CircuitPython 8, there is support for a settings.toml file. This is a file that is stored on your CIRCUITPY drive, that contains all of your secret network information, such as your SSID, SSID password and any API keys for IoT services. It is designed to separate your sensitive information from your code.py file so you are able to share your code without sharing your credentials.

CircuitPython previously used a secrets.py file for this purpose. The settings.toml file is quite similar.

CircuitPython settings.toml File

This section will provide a couple of examples of what your settings.toml file should look like, specifically for CircuitPython WiFi projects in general.

The most minimal settings.toml file must contain your WiFi SSID and password, as that is the minimum required to connect to WiFi. Copy this example, paste it into your settings.toml, and update:

• your_wifi_ssid
• your_wifi_password

CIRCUITPY_WIFI_SSID = "your_wifi_ssid"
CIRCUITPY_WIFI_PASSWORD = "your_wifi_password"

CIRCUITPY_WIFI_SSID = "your_wifi_ssid"
CIRCUITPY_WIFI_PASSWORD = "your_wifi_password"

Many CircuitPython network-connected projects on the Adafruit Learn System involve using Adafruit IO. For these projects, you must also include your Adafruit IO username and key. Copy the following example, paste it into your settings.toml file, and update:

• your_wifi_ssid
• your_wifi_password
• your_aio_username
• your_aio_key

CIRCUITPY_WIFI_SSID = "your_wifi_ssid"
CIRCUITPY_WIFI_PASSWORD = "your_wifi_password"
ADAFRUIT_AIO_USERNAME = "your_aio_username"
ADAFRUIT_AIO_KEY = "your_aio_key"

CIRCUITPY_WIFI_SSID = "your_wifi_ssid"
CIRCUITPY_WIFI_PASSWORD = "your_wifi_password"
ADAFRUIT_AIO_USERNAME = "your_aio_username"
ADAFRUIT_AIO_KEY = "your_aio_key"

Some projects use different variable names for the entries in the settings.toml file. For example, a project might use ADAFRUIT_AIO_ID in the place of ADAFRUIT_AIO_USERNAME. If you run into connectivity issues, one of the first things to check is that the names in the settings.toml file match the names in the code.

settings.toml File Tips

Here is an example settings.toml file.

# Comments are supported
CIRCUITPY_WIFI_SSID = "guest wifi"
CIRCUITPY_WIFI_PASSWORD = "guessable"
CIRCUITPY_WEB_API_PORT = 80
CIRCUITPY_WEB_API_PASSWORD = "passw0rd"
test_variable = "this is a test"
thumbs_up = "\U0001f44d"

# Comments are supported
CIRCUITPY_WIFI_SSID = "guest wifi"
CIRCUITPY_WIFI_PASSWORD = "guessable"
CIRCUITPY_WEB_API_PORT = 80
CIRCUITPY_WEB_API_PASSWORD = "passw0rd"
test_variable = "this is a test"
thumbs_up = "\U0001f44d"

In a settings.toml file, it's important to keep these factors in mind:

• Strings are wrapped in double quotes; ex: "your-string-here"
• Integers are not quoted and may be written in decimal with optional sign (+1, -1, 1000) or hexadecimal (0xabcd).
  • Floats (decimal numbers), octal (0o567) and binary (0b11011) are not supported.
• Use \u escapes for weird characters, \x and \ooo escapes are not available in .toml files
  • Example: \U0001f44d for 👍 (thumbs up emoji) and \u20ac for € (EUR sign)
• Unicode emoji, and non-ASCII characters, stand for themselves as long as you're careful to save in "UTF-8 without BOM" format

Accessing Your settings.toml Information in code.py

In your code.py file, you'll need to import the os library to access the settings.toml file. Your settings are accessed with the os.getenv() function. You'll pass your settings entry to the function to import it into the code.py file.

import os

print(os.getenv("test_variable"))

import os

print(os.getenv("test_variable"))

In the upcoming CircuitPython WiFi examples, you'll see how the settings.toml file is used for connecting to your SSID and accessing your API keys.