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Settings

Settings builtin package provides a friendly layer to read/write objects from the device flash. Keep it small, there's not a lot of space!

tip

In Visual Studio Code, open the command palette and run DeviceScript: Add Device Settings....

.env files​

Don't store secrets or settings in the code, use .env files instead.

  • ./.env.defaults: store general settings (tracked by version control)
  • ./.env.local: store secrets or override for general settings (untracked by version control)

The .env* file use a similar format to node.js .env file. The content will be transfered in the device flash when deploying the DeviceScript bytecode.

caution

The setting keys should be shorter than 14 characters!

./.env.defaults
# Default settings
# This file is tracked by git.
# DO NOT store secrets in this file.
temperature=68
./.env.local
# Local settings and secrets
# This file is/should **NOT** tracked by git
temperature=70 # override
PASSWORD=secret
tip

In Visual Studio Code, open the command palette and run DeviceScript: Add Device Settings.... From the CLI, run devs add settings.

Special Settings​

Some settings entries are treaty specially and routed to other services:

  • WIFI_SSID: set the WiFi SSID to connect to
  • WIFI_PWD: set the WiFi password (skip or leave empty to connect to open WiFi)

Using settings​

Once your .env files are ready, you can use readSetting and writeSetting to read/write settings.

import { Temperature, Button } from "@devicescript/core"
import { readSetting, writeSetting } from "@devicescript/settings"

const temperature = new Temperature()
const button = new Button()
let threshold = await readSetting<number>("temperature")

// show alert when temperature is above threshold
temperature.reading.subscribe(t => {
    if (t > threshold) {
        // too hot!
        console.log("hot!")
    }
})

// increase threshold when button is pressed
button.down.subscribe(async () => {
    threshold++
    await writeSetting("temperature", threshold)
})

Clearing​

You can use the command DeviceScript: Clear Device Setings... to clear the settings of the currently connected device.

See also​