Velux ESP8266 Control

2024-01-21 723 words 4 minutes

Contents

Velux ESP8266 Control

This is a small project to extend the functionality of a VELUX INTEGRA Funk-Wandschalter KLI 310 with WiFi. In combination with a MQTT server, Homebridge and some glue logic this can be used to cheaply make your Velux windows Apple Home Kit compatible, connect it to Homeassistant or similar. The original remote with its 3 buttons stays functional, we just add a new way to bridge the buttons via GPIOs of the ESP8266.

Parts

VELUX INTEGRA Wireless Remote KLI 310
USB Power Supply
ESP8266 dev kit, I used a NodeMCU
Cables
Solder
3D printed back

Electronics

The esp8266 pulls down the GPIOs to simulate button presses. The remote uses a common ground. The Remote usually runs on 3V (2x AAA), so the ESP8266 can be powered from the same source. To bridge the buttons, I soldered cables to the button contacts and connected them to the ESP8266. The availability of test point pads on the remote PCB made this very easy.

Color	Signal/Usage
Black	To common GND -> ESP8266 GND
Red	3.3V Output of the ESP8266 dev kit VReg out -> ESP8266 3.3V
Green	Up Button -> ESP8266 GPIO14
Blue	Stop Button -> ESP8266 GPIO12
Yellow	Down Button -> ESP8266 GPIO13

3D Printed Parts

To fit the ESP8266 I designed a simple replacement back for the available on Prusa Printables. It snaps together with the original front and has holes for mounting it to a wall.

Arduino Sketch

Platformio.ini:

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[env:nodemcuv2]
platform = espressif8266
board = nodemcuv2
framework = arduino
lib_deps = 
    knolleary/PubSubClient@^2.8
monitor_speed = 115200

main.cpp:

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#include <WiFiClientSecure.h>
#include <PubSubClient.h>
#include <ESP8266WiFi.h>

const char *ssid = "WiFi-SSID";
const char *password = "WiFI-PASSWORD";

const char *mqtt_server = "SERVER-IP";
const char *mqtt_username = "MQTT-USER";
const char *mqtt_password = "MQTT-PASSWORD";

const char *mqtt_topic = "velux_remote/commands";

uint8_t down_gpio = 14;
uint8_t stop_gpio = 12;
uint8_t up_gpio = 13;

WiFiClientSecure espClient;
PubSubClient client(espClient);

void callback(char *topic, byte *message, unsigned int length);
void reconnect();

void setup()
{
  Serial.begin(115200);
  WiFi.begin(ssid, password);

  // Setup GPIOs
  pinMode(down_gpio, OUTPUT);
  pinMode(stop_gpio, OUTPUT);
  pinMode(up_gpio, OUTPUT);
  digitalWrite(down_gpio, HIGH);
  digitalWrite(stop_gpio, HIGH);
  digitalWrite(up_gpio, HIGH);

  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);
    Serial.print("Connecting to ");
    Serial.println(ssid);
  }

  Serial.print("Connected with IP: ");
  Serial.println(WiFi.localIP());
  // openssl x509 -noout -fingerprint -sha1 -inform pem -in server.crt
  espClient.setFingerprint("A6 AE 85 65 63 DD D8 7C 70 F7 92 73 DE 8F 18 2B 9F DA 0A 76");
  // while (!client.connected())
  client.setServer(mqtt_server, 8883);
  client.setCallback(callback);
  while (true)
  {
    if (!client.connected())
    {
      reconnect();
    }
    else
    {
      yield();
      client.loop(); // ESP32 will be able to write received datas to UART monitor
    }
  }

  for (int i = 0; i <= 1000; i++)
  {

    char payload[10];
    itoa(i, payload, 10);
    client.publish("DemoTopic", payload);
  }
}

void loop()
{
}

void pushButton(uint8_t gpio)
{
  digitalWrite(gpio, LOW);
  delay(1000);
  digitalWrite(gpio, HIGH);
}

void callback(char *topic, byte *message, unsigned int length)
{
  Serial.print("Message arrived on topic: ");
  Serial.print(topic);
  Serial.print(". Message: ");
  String messageTemp;

  for (uint i = 0; i < length; i++)
  {
    messageTemp += (char)message[i];
  }
  Serial.println(messageTemp);
  if (messageTemp == "up")
  {
    pushButton(up_gpio);
  }
  else if (messageTemp == "down")
  {
    pushButton(down_gpio);
  }
  else if (messageTemp == "stop")
  {
    pushButton(stop_gpio);
  }
  Serial.println();
}

void reconnect()
{
  // Loop until we're reconnected
  while (!client.connected())
  {
    Serial.print("Attempting MQTT connection...");
    // Attempt to connect
    if (client.connect("ESP32Client", mqtt_username, mqtt_password))
    {
      Serial.println("connected");
      client.subscribe(mqtt_topic);
      Serial.println("Subscribed to DemoTopic");
    }
    else
    {
      Serial.print("failed, rc=");
      Serial.print(client.state());
      Serial.println(" try again in 5 seconds");
      // Wait 5 seconds before retrying
      delay(5000);
    }
  }
}