ESP Thing Server

A simple server for the ESP8266 and ESP32, that implements the W3C Web of Things API.

Installation

PlatformIO

Install the PlatformIO CLI via Python with pip install platformio.

Add the esp-thingserver library through PlatformIO's package management interface. For example, in your projects platformio.ini file, include:

[global]
lib_deps =
    https://github.com/labthings/esp-thingserver

Using PlatformIO Core (CLI)

Run platformio lib install from within your project directory to install all dependencies, and run platformio run -e huzzah -t upload to build and upload (replace huzzah with your boards environment).

See the examples folder for platformio.ini examples.

Example

platformio.ini

[platformio]
env_default= esp32

[global]
lib_deps =
    https://github.com/labthings/esp-thingserver
monitor_speed = 115200

[env:esp32]
platform = espressif32
board = esp32dev
framework = arduino
lib_deps =
    ${global.lib_deps}
lib_ldf_mode = deep+
monitor_speed =  ${global.monitor_speed}

[env:huzzah]
platform = espressif8266
board = huzzah
framework = arduino
lib_deps =
    ${global.lib_deps}
lib_ldf_mode = deep+
monitor_speed =  ${global.monitor_speed}

main.cpp

#include <Arduino.h>
#include <Thing.h>
#include "WebThingAdapter.h"

// TODO: Hardcode your wifi credentials here (and keep it private)
const char *ssid = "public";
const char *password = "";

#if defined(LED_BUILTIN)
const int ledPin = LED_BUILTIN;
#else
const int ledPin = 13; // manually configure LED pin
#endif

WebThingAdapter *adapter;

const char *ledTypes[] = {"OnOffSwitch", "Light", nullptr};
ThingDevice led("led", "Built-in LED", ledTypes);
ThingProperty ledOn("on", "", BOOLEAN, "OnOffProperty");

bool lastOn = false;

void setup(void) {
  pinMode(ledPin, OUTPUT);
  digitalWrite(ledPin, HIGH);
  Serial.begin(115200);
  Serial.println("");
  Serial.print("Connecting to \"");
  Serial.print(ssid);
  Serial.println("\"");
#if defined(ESP8266) || defined(ESP32)
  WiFi.mode(WIFI_STA);
#endif
  WiFi.begin(ssid, password);
  Serial.println("");

  // Wait for connection
  bool blink = true;
  while (WiFi.status() != WL_CONNECTED) {
    delay(500);
    Serial.print(".");
    digitalWrite(ledPin, blink ? LOW : HIGH); // active low led
    blink = !blink;
  }
  digitalWrite(ledPin, HIGH); // active low led

  Serial.println("");
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
  
  led.addProperty(&ledOn);

  adapter = new WebThingAdapter(&led, "w25", WiFi.localIP());
  adapter->begin();

  Serial.println("HTTP server started");
  Serial.print("http://");
  Serial.print(WiFi.localIP());
  Serial.print("/things/");
  Serial.println(led.id);
}

void loop(void) {
  adapter->update();
  bool on = ledOn.getValue().boolean;
  digitalWrite(ledPin, on ? LOW : HIGH); // active low led
  if (on != lastOn) {
    Serial.print(led.id);
    Serial.print(": ");
    Serial.println(on);
  }
  lastOn = on;
}

Configuration

• If you have a complex device with large thing descriptions, you may need to increase the size of the JSON buffers. The buffer sizes are configurable as such:

  // By default, buffers are 256 bytes for small documents, 1024 for larger ones
  
  // To use a pre-defined set of larger JSON buffers (4x larger)
  #define LARGE_JSON_BUFFERS 1
  
  // Else, you can define your own size
  #define SMALL_JSON_DOCUMENT_SIZE <something>
  #define LARGE_JSON_DOCUMENT_SIZE <something>
  
  #include <Thing.h>
  #include <WebThingAdapter.h>

Acknowledgements

ESP Thing Server was originally based on the Mozilla IoT WebThing-Arduino library.