Alex2ESP/examples

Examples

One folder per kind of device. Every sketch is complete: Wi-Fi, the MQTT session, one device (MultiDevice: two) with its own endpoint id and name, and one handler for its directives.

Sketch	Device	Interfaces	Endpoint id
Light	a lamp, on and off	PowerController	esp-light
DimmableLight	a lamp with PWM brightness	PowerController, BrightnessController	esp-dimmable-light
ColorTemperatureLight	a lamp with a warm and a cold channel, 2200 K to 7000 K	PowerController, BrightnessController, ColorTemperatureController	esp-white-light
ColorLight	an RGB lamp	PowerController, BrightnessController, ColorController	esp-color-light
TemperatureSensor	a thermometer; a ChangeReport after a change of more than 0.5 degrees, at most one a minute	TemperatureSensor	esp-temperature
ContactSensor	a door contact on a GPIO; a ChangeReport on every change	ContactSensor	esp-contact
Blind	a blind with a position of 0 to 100 and the words open, close, raise, lower	RangeController Blind.Lift with semantics	esp-blind
Thermostat	HEAT, COOL, AUTO and OFF, one setpoint or two, the errors of the thermostat	ThermostatController, TemperatureSensor	esp-thermostat
Lock	a bolt that takes 3 s: DeferredResponse, then the answer from loop()	LockController	esp-lock
Scene	a scene that switches two outputs	SceneController	esp-scene
Doorbell	a button on a GPIO; DoorbellPress on every press	DoorbellEventSource	esp-doorbell
MultiDevice	two lamps, two endpoints, one handler	PowerController	esp-multi-left, esp-multi-right

Every device announces EndpointHealth as well and reports connectivity with its state.

The sketches in legacy/ are the examples of 1.x, unchanged. They use registerEvent() and the Add...Prop() names and are kept to show that a 1.x sketch compiles against 2.0. New sketches start from the ones above.

Before flashing

Fill in the five constants at the top of the sketch: the Wi-Fi network and the MQTT user name, password and root topic of your Alex2MQTT account.

const char *WIFI_SSID = "";
const char *WIFI_PASSWORD = "";

const char *ALEXA_USERNAME = "";
const char *ALEXA_PASSWORD = "";
const char *ALEXA_ROOT_TOPIC = "";

Two boards with the same endpoint id on one account are one device to Alexa. Change the id and the name in getDevice() when you flash a sketch a second time.

Each sketch names the pins it uses by GPIO number, with the label of the Wemos D1 mini in a comment. The serial output is at 74880 baud.

Wi-Fi

connectWiFi() waits for the network for 30 s at the most. Without a connection it prints the status and the two constants to check, and the sketch carries on: the ESP8266 keeps trying to join, and alexa.loop() opens the MQTT session once Wi-Fi is up.

Building

Arduino IDE: a sketch is a folder with an .ino of the same name, which is how the IDE opens it.

PlatformIO: copy the .ino into src/ of a project that has the library in lib_deps, or make the folder of the sketch the source directory of the project (src_dir, or the environment variable of the same meaning). In a project with a d1_mini environment and the library:

PLATFORMIO_SRC_DIR=/path/to/Alex2ESP/examples/Light pio run -e d1_mini

This is how the sizes below were built. The sketches define every function before it is used and include Arduino.h, so they are also valid as a .cpp file.

Size

Static RAM and flash as PlatformIO reports them for d1_mini (espressif8266 4.2.1, Arduino core 3.1.2, AsyncMqttClient 0.9.0, ArduinoJson 7.4.3), built from this folder as committed, with empty credentials and the default log level. A D1 mini has 81,920 bytes of RAM; what is not static is the heap.

Sketch	Static RAM (bytes)	Flash (bytes)
Light	30,616	332,705
DimmableLight	30,692	336,905
ColorTemperatureLight	30,808	337,629
ColorLight	30,748	338,797
TemperatureSensor	30,572	333,353
ContactSensor	30,584	333,017
Blind	30,860	336,665
Thermostat	31,044	337,657
Lock	30,648	333,597
Scene	30,640	333,629
Doorbell	30,584	333,121
MultiDevice	30,672	332,865
legacy/basicLight	30,520	334,129
legacy/lightWithBrightness	30,648	338,069
legacy/lightWithColorTemp	30,828	338,793
legacy/tempSensor	30,412	332,921
legacy/blindControl	30,568	335,417

What has been tried

The sketches of this folder were compiled with PlatformIO, with 0 warnings. They have not been built with the Arduino IDE and have not run on a board yet. What each announces in discovery is checked by the host tests in test/test_examples.

With this library on a Wemos D1 mini, a real Alexa account and other sketches (2026-09-28), Alexa discovered and drove PowerController, BrightnessController, ColorTemperatureController, one instance each of ToggleController, RangeController and ModeController, a lock with its deferred answer and a scene, and took a ChangeReport, an ErrorResponse and the press of a doorbell. Not tried with Alexa from this library: ColorController, ThermostatController and the sensors. Voice commands have not been tried.

Limits

• Doorbell, ContactSensor: an event or a change while there is no session with the broker is not sent later.
• Lock: the answer after the DeferredResponse is sent once. If the session is lost while the bolt moves, Alexa gets the state with its next ReportState.
• Blind, Scene, Thermostat, the lamps: the state is kept in RAM and starts from the values in the sketch after a reset.