Controlling the lights of a Novy Crystal 26050 cooking hood when the Zigbee kitchen lights turn on

Posted on 01 January 2024 by spectracoder 12 min

Controlling the lights of a Novy Crystal 26050 cooking hood when the Zigbee kitchen lights turn on

A couple of months ago I got a new kitchen installed. The cupboards above the countertop have a milk-glass base plate, which have LED lights in them. They light both the countertop and the inside of the cupboard. It looks very stylish! They are controlled via Zigbee, connected to my Home Assistant installation. I've also added a motion detector (PIR), so that when I enter the kitchen the lights come on.

Next to those cupboards is my cooking hood, the Novy Crystal 26050. It is built-in in the cupboard, so it doesn't stand out. It also has LED lights in it. But the problem is, they don't come on when I enter the kitchen. This leaves a dark area on that part of the countertop.

The Novy Crystal 26050 with the cupboards next to it.

The manual of the Novy cooking hood mentions the existence of a remote control, which is sold separately for way too much money. But after doing some research, I found out it is controlled using 433MHz.

I had an XD-FST FS1000A 433MHz transmitter and receiver lying around from a previous project, so I decided to tinker with an Arduino Uno to see if I could trigger the lights of the cooking hood somehow. Since I didn't have the remote control for the cooking hood, there was no way to know what the binary code would be that the cooking hood would respond to. Luckily, I found some codes online from someone else. When I sent one of those codes using the RCSwitch library, it worked! I could switch the lights on and off remotely.

XD-FST FS1000A

With that working, how could I connect this to my existing Home Assistant system? With an ESP32 of course! Since it has WiFi, I can connect it to my network and read the status of the kitchen lights using the API of Home Assistant. I ordered an ESP32 Dev Kit C V2 online, and it arrived the next day.

For convenience, I soldered the XD-FST FS1000A 433mhz transmitter directly to the ESP32. By setting pin 22 to HIGH, it powers the transmitter while pin 23 is used to send data. The pin next to those is ground.

For convenience, I soldered the XD-FST FS1000A 433mhz transmitter directly to the ESP32.

I started by making a config.h file which holds all important details.

/// Make a copy of this file, and rename it to "config.h" to make it work with the EPS32_Novy_Commander.ino script.
/// Change the variables in ths file to your needs. 
const String HOSTNAME = "ESP32 Novy Commander";
const char* SSID = "Your wifi name";
const char* PASSWORD =  "Your password";
const int REFRESH_TIME = 1000;  ///milliseconds

/// For convenience, I soldered the 433mhz transmitter directly to the ESP32.
/// By setting pin 22 to HIGH, it powers the transmitter while pin 23 is used to send data.
/// The pin next to those is ground.
const int TRANSMIT_433MHZ_PIN = 23;
const int POWER_433MHZ_PIN = 22;

/// In my own home I have two wifi routers using the same SSID (wifi name). 
/// The ESP32 isn't very good at picking the strongest signal by itself reliably, so I needed a way to tell it which router to pick.
/// By defining the Mac address of the router in the ROUTER_TO_CONNECT_TO variable, it only connects to that router.
/// I made two variables for debugging purposes.
const uint8_t BSSID_BEDROOM[6] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00}; /// Mac Address of the bedroom router to connect to
const uint8_t BSSID_LIVINGROOM[6] = {0x00, 0x00, 0x00, 0x00, 0x00, 0x00}; /// Mac Address of the living room router to connect to

const uint8_t* ROUTER_TO_CONNECT_TO = BSSID_BEDROOM; /// Selects the router to connect to

/// Create a Long-Lived Access Token in Home Assistant to access its API. Be sure to add the word "Bearer " (with a space after it) in front of the token.
const char* HOME_ASSISTANT_TOKEN = "Bearer kajhfsdklfasglksajglkasglaslglksadjglkjdsglkjagjdgbflbkdsfjdlsdfasdlkfhghasjfgeyrtaefhjgsdkjhfgsjfgkaekgfasjfbsdvnbbvzvbshdkgfgjsdalgdslkaglksjdasdgagagaga";
const char* HOME_ASSISTANT_LIGHT_URL = "http://192.168.1.7:80/api/states/light.examplelight"; /// Url of the Home Assistant API lights you want to use.

/// The 433mhz Novy device codes I borrowed from https://github.com/abelgomez/rf-mqtt-bridge/blob/master/src/NovyController.cpp
/// Programmable code (from 1 to 10), see 4 first bits above
static const String NOVY_DEVICE_CODE[] = {
    "0101",
    "1001",
    "0001",
    "1110",
    "0110",
    "1010",
    "0010",
    "1100",
    "0100",
    "1000",
};

/// Prefix (next 4 bits, not sure what it means, if it is always fixed, or if it is part of the command code)
static const String NOVY_PREFIX = "0101";

/// Commands to be sent (code + prefix + command)
static const String NOVY_COMMAND_LIGHT = "0111010001";
static const String NOVY_COMMAND_POWER = "0111010011";
static const String NOVY_COMMAND_PLUS =  "0101";
static const String NOVY_COMMAND_MINUS = "0110";
static const String NOVY_COMMAND_NOVY =  "0100";

To be able to access the API of your Home Assistant, you will need to generate a Long-Lived Access Token. Log in onto your Home Assistant web interface, and click on your profile name. There, on the bottom of the page, you can generate the token. Copy and paste it into the config.h file.

And then I created the main script. It creates a webpage which you can access using the IP address of the ESP32. On the page you will see the status of the lights.

ESP32 Novy Commander Webpage

/// The main goal of this script is to control the lights of the Novy cooking hood when the Zigbee kitchen lights are turned on or off.
/// This script looks at the API of Home Assistant to determine the on or off state of the kitchen lights, and sends a 433mhz signal to the connected 433mhz transmitter.
/// The ip address of the ESP32 shows a basic status web page with the ability to reboot the device.
/// SpectraCoder 01-12-2023

#include <WiFi.h>
#include <WiFiClient.h>
#include <WebServer.h>
#include <ESPmDNS.h>
#include <HTTPClient.h>
#include <ArduinoJson.h>
#include <RCSwitch.h>
#include <ESPmDNS.h>
#include <WiFiUdp.h>
#include <ArduinoOTA.h>

/// IMPORTANT! This file holds all credentials and settings.
/// Make a copy of config.example.h and rename it to config.h to make this work with your own setup.
#include "config.h"
#include "favicon.h"

bool isKitchenLightsOn = false;
int kitchenLightBrightness = 0;
bool isNovyLightOn = false;

WebServer server(80);

RCSwitch transmitter = RCSwitch();

String returnedAPIString = "";

void setup() {
  Serial.begin(115200);
  pinMode(POWER_433MHZ_PIN, OUTPUT);
  digitalWrite(POWER_433MHZ_PIN, HIGH);

  connectWifi();
  startServer();

  transmitter.enableTransmit(TRANSMIT_433MHZ_PIN);
  transmitter.setPulseLength(350);
  transmitter.setProtocol(12);

  ArduinoWifiUpdater();
}

///This function allows for firmware uploads through wifi,
///instead of connecting the ESP32 directly via usb.
void ArduinoWifiUpdater() {
  ArduinoOTA
    .onStart([]() {
      String type;
      if (ArduinoOTA.getCommand() == U_FLASH)
        type = "sketch";
      else  // U_SPIFFS
        type = "filesystem";

      // NOTE: if updating SPIFFS this would be the place to unmount SPIFFS using SPIFFS.end()
      Serial.println("Start updating " + type);
    })
    .onEnd([]() {
      Serial.println("\nEnd");
    })
    .onProgress([](unsigned int progress, unsigned int total) {
      Serial.printf("Progress: %u%%\r", (progress / (total / 100)));
    })
    .onError([](ota_error_t error) {
      Serial.printf("Error[%u]: ", error);
      if (error == OTA_AUTH_ERROR) Serial.println("Auth Failed");
      else if (error == OTA_BEGIN_ERROR) Serial.println("Begin Failed");
      else if (error == OTA_CONNECT_ERROR) Serial.println("Connect Failed");
      else if (error == OTA_RECEIVE_ERROR) Serial.println("Receive Failed");
      else if (error == OTA_END_ERROR) Serial.println("End Failed");
    });

  ArduinoOTA.begin();
}

void startServer() 
{
  server.stop();
  server.on("/", webpage);
  server.on("/reboot", reboot);
  server.on("/favicon.ico", HTTP_GET, getFavicon);
  server.begin();
}

void connectWifi() {
  delay(4000);  //Delay needed before calling the WiFi.begin

  WiFi.mode(WIFI_STA);
  WiFi.disconnect(true);
  WiFi.config(INADDR_NONE, INADDR_NONE, INADDR_NONE, INADDR_NONE);
  WiFi.setHostname(HOSTNAME.c_str());
  WiFi.begin(SSID, PASSWORD, 0, ROUTER_TO_CONNECT_TO);

  while (WiFi.status() != WL_CONNECTED) {
    delay(1000);
    Serial.println("Connecting to WiFi..");
  }

  Serial.println("Connected to the WiFi network " + String(SSID));
  Serial.println(WiFi.localIP());
}

void loop() {
  //Check the current connection status
  if ((WiFi.status() == WL_CONNECTED)) {
    ArduinoOTA.handle();

    returnedAPIString = getHomeAssistantAPIString();

    isKitchenLightsOn = convertJsonToBool(returnedAPIString);
    kitchenLightBrightness = convertJsonToBrightness(returnedAPIString);

    Serial.println(isKitchenLightsOn ? "The kitchen lights are on" : "The kitchen lights are off");

    if (isKitchenLightsOn && !isNovyLightOn) 
    {

      /// The Novy cooking hood lights always start up in full brightness. To dim them down, you need to press and hold the dim button.
      /// It is possible to simulate that button hold by sending the LightOn signal multiple times in a row.
      /// I decided against that, and just leave them off when the other kitchen lights are dimmed below the threshold. (e.g. at night)
      /// Otherwise there would be a flash of light from the cooking hood before it dimmed down to a good level.
      if (kitchenLightBrightness > 200) 
      {
        LightOn();
        isNovyLightOn = true;
        Serial.println("Turned on Novy light");
      }
    }

    if (!isKitchenLightsOn && isNovyLightOn) 
    {
      LightOff();
      isNovyLightOn = false;
      Serial.println("Turned off Novy light");
    }
  }

  if (WiFi.status() != WL_CONNECTED) {
    Serial.println("Lost connection. Reconnecting...");

    connectWifi();
    startServer();
  }

  server.handleClient();

  delay(REFRESH_TIME);
}

String getHomeAssistantAPIString() {
  HTTPClient http;
  String string = "";
  //Url of the Home Assistant API kitchen lights
  http.begin(HOME_ASSISTANT_LIGHT_URL);
  http.addHeader("Authorization", HOME_ASSISTANT_TOKEN);  //Adds the authorization header
  int httpCode = http.GET();                              //Makes the request

  if (httpCode > 0) {
    string = http.getString();

    Serial.print("WiFi signal strength: ");
    Serial.println(WiFi.RSSI());
  } else {
    Serial.println("Error on HTTP request");
  }

  http.end();  //Frees the resources

  return string;
}

/// Checks to which wifi router the ESP32 is connected by comparing the mac addresses of the configured routers in config.h.
/// It returns a friendly name to know which one it is connected to.
String GetFriendlyRouterName() 
{
  /// This compares the first n bytes (where n is the third argument, in this case 6) of
  /// the block of memory pointed by bssid with the first n bytes pointed by bssid_bedroom or bssid_livingroom.
  /// It returns 0 if the two blocks of memory are identical.
  String routerName = "";
  uint8_t* bssid = WiFi.BSSID();

  if (memcmp(bssid, BSSID_BEDROOM, 6) == 0) 
  {
    routerName = "bedroom";
  } 
  else if (memcmp(bssid, BSSID_LIVINGROOM, 6) == 0) 
  {
    routerName = "living room";
  } 
  else 
  {
    routerName = "unknown BSSID";
  }

  return routerName;
}

void getFavicon ()
{
  server.sendHeader("Content-Type", "image/x-icon");
  server.send_P(200, "image/x-icon", (const char*)FAVICON, sizeof(FAVICON));
}

void webpage() {
  int rssi = WiFi.RSSI();
  int signalStrength = map(rssi, -100, -50, 0, 100);
  signalStrength = constrain(signalStrength, 0, 100);

  String routerName = GetFriendlyRouterName();

  String html = R"(
  <html>
    <head>
     <title>)" + String(HOSTNAME)
                + R"(</title>
    <meta http-equiv="refresh" content=")"
                + String(REFRESH_TIME / 1000) + R"(">
    <link rel="icon" type="image/x-icon" href="/favicon.ico">
      <style>
        body {
          background-color: #111111;          
        }
        h1{
          font-family: verdana;
          color: white;
        }
        p {
          font-family: verdana;
          color: white;
        }
        pre{
          color: lightgray;
        }
        .json{
          margin-top: 50px;
          background-color: black;
        }
        .button {
          background-color: blue;
          border: none;
          color: white;
          padding: 15px 32px;
          text-align: center;
          text-decoration: none;
          display: inline-block;
          font-size: 16px;
          margin: 4px 2px;
          cursor: pointer;
        }
      </style>
    </head>
    <body>
      <h1>)" + String(HOSTNAME)
                + R"(</h1>
      <div>
        <p>Connected to )"
                + WiFi.SSID() + R"( ()" + routerName + R"()</p>
        <p>WiFi Signal Strength: )"
                + String(signalStrength) + R"(% ()" + String(rssi) + R"()</p>
        <p>)" + String(isKitchenLightsOn ? "The kitchen lights are on" : "The kitchen lights are off")
                + R"(</p>
        <p>Brightness: )"
                + String(kitchenLightBrightness) + R"(</p>
        <p>Used Heap Size: )"
                + getUsedHeapPercentage() + R"(</p>
        <p>Uptime: )"
                + getUptime() + R"(</p>
        <button class="button" onclick="location.href='/reboot'">Reboot</button>
      </div>
      <div class='json'>
        <pre>)" + beautifyJson(returnedAPIString)
                + R"(</pre>
      </div>
    </body>
  </html>
  )";

  server.send(200, "text/html", html);
}

void reboot() {
  String html = R"(<html>
                  <head>
                  <title>Rebooting...</title>
                    <meta http-equiv='refresh' content='10; url=/'>
                      <style>
                        body {
                          background-color: #111111;          
                        }                      
                        p {
                          font-family: verdana;
                          color: white;
                        }                        
                      </style>
                  </head>
                  <body>
                    <p>Rebooting...</p>
                  </body>
                </html>)";

  server.send(200, "text/html", html);
  delay(1000);
  ESP.restart();
}

String getUptime() 
{
  uint64_t timeSinceBoot = esp_timer_get_time();
  uint64_t seconds = timeSinceBoot / 1000000;
  uint64_t minutes = seconds / 60;
  uint64_t hours = minutes / 60;
  uint64_t days = hours / 24;
  seconds = seconds % 60;
  minutes = minutes % 60;
  hours = hours % 24;
  String uptime = String(days) + " days, " + String(hours) + " hours, " + String(minutes) + " minutes, " + String(seconds) + " seconds";

  return uptime;
}


/// Function to calculate the percentage of used memory
String getUsedHeapPercentage() 
{
  // Get the free heap size
  uint32_t freeHeap = esp_get_free_heap_size();

  // Define the total heap size
  uint32_t totalHeap = 320 * 1024;  // 320KB

  // Calculate the used heap size
  uint32_t usedHeap = (freeHeap > totalHeap) ? 0 : (totalHeap - freeHeap);

  // Calculate the percentage of used heap
  float usedHeapPercentage = ((float)usedHeap / totalHeap) * 100;

  // Return the used heap size and percentage as a string
  return String(usedHeap) + " bytes (" + String(usedHeapPercentage) + "%)";
}

String beautifyJson(String jsonString) 
{
  //Create an empty Json object
  StaticJsonDocument<1500> jsonDoc;

  //Load the received data into a JSON object
  DeserializationError error = deserializeJson(jsonDoc, jsonString);

  if (!error) 
  {
    String prettyJson;
    serializeJsonPretty(jsonDoc, prettyJson);
    return prettyJson;
  } 
  else 
  {
    return String("ERROR: Json could not be read");
  }
}

/// Converts the "brightness" property inside the json (returned by Home Assistant) to an int.
/// Returns an int from 0 to 255.
int convertJsonToBrightness(String jsonString) 
{
  //Create an empty Json object
  StaticJsonDocument<1500> jsonDoc;

  //Load the received data into a JSON object
  DeserializationError error = deserializeJson(jsonDoc, jsonString);

  // Test if parsing succeeds.
  if (error) 
  {
    Serial.print(F("deserializeJson() failed: "));
    Serial.println(error.f_str());
    return 0;
  }

  JsonObject root = jsonDoc.as<JsonObject>();
  JsonObject attributes = root["attributes"].as<JsonObject>();
  int brightness = attributes["brightness"];

  return brightness;
}


///Converts the "state" property inside the json (returned by Home Assistant) to a bool.
///Returns true if the state is "on", false if it is "off".
bool convertJsonToBool(String jsonString) 
{
  //Create an empty Json object
  StaticJsonDocument<1500> jsonDoc;

  //Load the received data into a JSON object
  DeserializationError error = deserializeJson(jsonDoc, jsonString);

  // Test if parsing succeeds.
  if (error) 
  {
    Serial.print(F("deserializeJson() failed: "));
    Serial.println(error.f_str());
    return false;
  }

  // Get the state value inside the JSON object
  const char* state = jsonDoc["state"];

  // Convert to boolean
  bool isOn = strcmp(state, "on") == 0;

  return isOn;
}


void PressLight(int channelIndex) 
{
  Serial.print("Pressing light on channel ");
  Serial.println(channelIndex);
  Serial.print((NOVY_DEVICE_CODE[channelIndex] + NOVY_PREFIX + NOVY_COMMAND_LIGHT).c_str());
  Serial.println();
  //010101010111010001
  transmitter.send((NOVY_DEVICE_CODE[channelIndex] + NOVY_PREFIX + NOVY_COMMAND_LIGHT).c_str());
}

void LightOn() 
{
  PressLight(0);
}

void LightOff()
{
  PressLight(0);
}

Case

The case I 3D printed. I also designed and 3D printed a case for the ESP32 to fit the 433MHz transmitter. You can find the .stl file on my GitHub page.

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