{"id":243020,"date":"2026-06-22T14:51:18","date_gmt":"2026-06-22T12:51:18","guid":{"rendered":"https:\/\/emariete.com\/?p=243020"},"modified":"2026-07-07T09:09:46","modified_gmt":"2026-07-07T07:09:46","slug":"co2-gadget-wi-fi-guide","status":"publish","type":"post","link":"https:\/\/emariete.com\/en\/co2-gadget-guia-wifi\/","title":{"rendered":"CO2 Gadget WiFi Guide: Connection, Website and API"},"content":{"rendered":"<p class=\"wp-block-paragraph\">Configuring the Wi-Fi on your Gadget CO\u2082 meter is the first step towards accessing the web interface, the REST API and OTA updates via your browser. In this guide, you\u2019ll learn about the four available methods: the Sensirion MyAmbiance app, the captive portal, the serial menu and the preferences page.<\/p>\n\n\n\n\n\n\n<div style=\"background:#fff8dc;border:1px solid #e6c300;border-radius:8px;padding:12px 16px;margin:12px 0;font-size:14px;line-height:1.5;color:#333\">\n<strong>Documentation is currently being updated.<\/strong> We are currently reviewing and improving all our pages. You may come across a broken link or some content that hasn\u2019t been finalised yet. If you spot anything that isn\u2019t quite right, please help us fix it at <a href=\"https:\/\/github.com\/melkati\/CO2-Gadget\/issues\" style=\"color:#0066cc\">GitHub<\/a>.\n<\/div>\n\n\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n<p class=\"wp-block-paragraph\">Wi-Fi is the communications hub of the CO2 Gadget. You can use it to access the <strong>web interface<\/strong> from any browser, use <strong>MQTT<\/strong> to send data to Home Assistant, receive <strong>remote commands<\/strong>, to do <strong>OTA updates<\/strong> and consume the <strong>REST API<\/strong> to integrate your CO\u2082 monitor with other home automation systems. All this without relying on third-party cloud services \u2013 something very few commercial monitors offer.<\/p>\n\n\n<p class=\"wp-block-paragraph\">Here\u2019s everything you need to set up the Wi-Fi on your CO2 Gadget.<\/p>\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n<h2 class=\"wp-block-heading\">Default Wi-Fi settings<\/h2>\n\n\n<p class=\"wp-block-paragraph\">As soon as you flash CO2 Gadget for the first time, the Wi-Fi comes on <strong>disabled<\/strong>. BLE (Bluetooth Low Energy) is indeed active, allowing you to set up the Wi-Fi via the Sensirion MyAmbiance app without needing any buttons or a screen. It\u2019s that simple to have a <strong>high-quality CO\u2082 meter<\/strong> up and running in minutes.<\/p>\n\n\n<figure class=\"wp-block-table\"><table><thead><tr><th>Parameter<\/th><th>Value<\/th><\/tr><\/thead><tbody><tr><td>Wi-Fi<\/td><td>OFF<\/td><\/tr><tr><td>Hostname<\/td><td>`CO2-Gadget`<\/td><\/tr><tr><td>DHCP<\/td><td>Enabled (Automatic IP)<\/td><\/tr><tr><td>mDNS<\/td><td>Enabled<\/td><\/tr><tr><td>Captive Portal<\/td><td>Enabled (if no Wi-Fi is configured)<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n<h2 class=\"wp-block-heading\">How to connect your CO\u2082 monitor to Wi-Fi<\/h2>\n\n\n<p class=\"wp-block-paragraph\">You have <strong>4 ways<\/strong> To connect your CO\u2082 meter with CO2 Gadget to your Wi-Fi network, choose the option that suits you best:<\/p>\n\n\n<h3 class=\"wp-block-heading\">1. From the MyAmbiance app (recommended)<\/h3>\n\n\n<ol class=\"wp-block-list\">\n<li>Install <strong>Sensirion MyAmbiance<\/strong> (iOS \/ Android) \u2014 it\u2019s free<\/li>\n<li>Open the app and search for your device (`CO2-Gadget`)<\/li>\n<li>Go to <strong>Settings \u2192 Wi-Fi Configuration<\/strong><\/li>\n<li>Enter your SSID and password<\/li>\n<li>The meter connects automatically<\/li>\n<\/ol>\n\n\n<h3 class=\"wp-block-heading\">2. Captive portal (no app, no buttons)<\/h3>\n\n\n<p class=\"wp-block-paragraph\">If your meter <strong>Wi-Fi is not set up<\/strong>, when you switch it on for the first time, it creates its own network. Connect to it, and the captive portal will open automatically, allowing you to enter your network details. On iOS, if the portal doesn\u2019t load, open Safari and go to <code>http:\/\/192.168.4.1<\/code>.<\/p>\n\n\n<h3 class=\"wp-block-heading\">3. On-screen menu or via serial port<\/h3>\n\n\n<p class=\"wp-block-paragraph\">From the menu: <strong>Settings \u2192 Wi-Fi Settings \u2192 Wi-Fi Enable [ON]<\/strong>. Enter the SSID, password and hostname. Save by clicking <strong>Save Preferences<\/strong>.<\/p>\n\n\n<h3 class=\"wp-block-heading\">4. Preferences webpage<\/h3>\n\n\n<p class=\"wp-block-paragraph\">If you\u2019re already connected, you can switch networks from <code>http:\/\/ip<em>del<\/em>meter\/preferences.html<\/code><\/p>\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n<h2 class=\"wp-block-heading\">Web interface for your CO\u2082 meter<\/h2>\n\n\n<p class=\"wp-block-paragraph\">Once you\u2019re connected, open <code>http:\/\/CO2-Gadget.local<\/code> in any browser. The CO2 Gadget web interface features an Apple-style design with automatic dark\/light mode, something you won\u2019t find on any other commercially available meter in this price range.<\/p>\n\n\n<figure class=\"wp-block-table\"><table><thead><tr><th>Page<\/th><th>URL<\/th><th>Description<\/th><\/tr><\/thead><tbody><tr><td><strong>Home<\/strong><\/td><td>`\/`<\/td><td>CO\u2082, temperature and humidity dashboard<\/td><\/tr><tr><td><strong>Charts<\/strong><\/td><td>`\/charts.html`<\/td><td>Historical data with Chart.js, CSV\/JSON export<\/td><\/tr><tr><td><strong>Calibration<\/strong><\/td><td>`\/calibration.html`<\/td><td>Live FRC forced calibration<\/td><\/tr><tr><td><strong>Low Power<\/strong><\/td><td>`\/low_power.html`<\/td><td>Configuring low-power thresholds<\/td><\/tr><tr><td><strong>Preferences<\/strong><\/td><td>`\/preferences.html`<\/td><td>All device settings<\/td><\/tr><tr><td><strong>Status<\/strong><\/td><td>`\/status.html`<\/td><td>Version, RSSI, uptime and status<\/td><\/tr><tr><td><strong>OTA<\/strong><\/td><td>`\/update`<\/td><td>Web-based firmware update<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n<h2 class=\"wp-block-heading\">mDNS: name-based access<\/h2>\n\n\n<p class=\"wp-block-paragraph\">CO2 Gadget implements <strong>mDNS<\/strong>: Access your meter using its hostname, without having to find out its IP address: <code>http:\/\/CO2-Gadget.local<\/code>. Configurable in <strong>Settings \u2192 Wi-Fi Settings \u2192 Host<\/strong>.<\/p>\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n<h2 class=\"wp-block-heading\">REST API for professional integration<\/h2>\n\n\n<p class=\"wp-block-paragraph\">CO2 Gadget showcases a <strong>Full REST API<\/strong> to integrate your high-quality CO\u2082 meter with <strong>Home Assistant<\/strong>, <strong>Node-RED<\/strong>, <strong>Grafana<\/strong> and any other system. Commercial meters rarely offer such a comprehensive and well-documented API.<\/p>\n\n\n<pre class=\"wp-block-code\"><code>GET \/readCO2 \u2192 892 (ppm)\nGET \/readTemperature    \u2192 24.5 (\u00b0C)\nGET \/readHumidity \u2192 45.2 (%)\nGET \/status \u2192 Full system JSON\nGET \/settings?Param=Val \u2192 Change any setting\nPOST \/savePreferences   \u2192 Save multiple parameters<\/code><\/pre>\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n<h2 class=\"wp-block-heading\">Static IP for your meter<\/h2>\n\n\n<p class=\"wp-block-paragraph\">Set up a static IP address from <code>\/preferences.html<\/code> \u2192 active <strong>Use a static IP address<\/strong> and enter the IP address, subnet mask, gateway and DNS. Ideal for integration with Home Assistant.<\/p>\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n<h2 class=\"wp-block-heading\">Safety<\/h2>\n\n\n<p class=\"wp-block-paragraph\">Password fields are disabled by default because they are transmitted in plain text. Add <code>?relaxedSecurity=true<\/code> to the URL to enable them. During compilation, enable <code>WIFI_PRIVACY<\/code> to hide passwords via the serial port.<\/p>\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n<h2 class=\"wp-block-heading\">WiFi troubleshooting<\/h2>\n\n\n<figure class=\"wp-block-table\"><table><thead><tr><th>Problem<\/th><th>Solution<\/th><\/tr><\/thead><tbody><tr><td>It won't connect to the Wi-Fi<\/td><td>Check the SSID and password (max. 63 characters)<\/td><\/tr><tr><td>It switches off randomly<\/td><td>Weak signal \u2013 move the router closer or use a repeater<\/td><\/tr><tr><td>.local isn't working<\/td><td>If mDNS is blocked on your network, use the IP address directly<\/td><\/tr><tr><td>Captive portal won't load on iOS<\/td><td>Open Safari and type http:\/\/192.168.4.1<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n<h2 class=\"wp-block-heading\">Important notes<\/h2>\n\n\n<ul class=\"wp-block-list\">\n<li>Wi-Fi can be switched on or off without restarting the meter<\/li>\n<li>In LOW_POWER mode, Wi-Fi connects only every N cycles to save battery life<\/li>\n<li>CO2 Gadget only supports <strong>2.4 GHz networks<\/strong> (the ESP32 does not support 5 GHz)<\/li>\n<li>To use MQTT or Home Assistant, you need to have Wi-Fi enabled<\/li>\n<li><strong>A CO2 Gadget meter offers more features than most commercial meters, whilst costing several times as much<\/strong><\/li>\n<\/ul>\n\n\n<p class=\"wp-block-paragraph\">| I can\u2019t see any changes after configuring | You haven\u2019t saved | Go to <strong>Save Preferences<\/strong> in the menu or wait for the next cycle | | The website looks strange | Browser cache | Clear your cache or use an incognito window |<\/p>\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n<h2 class=\"wp-block-heading\">Important notes<\/h2>\n\n\n<ul class=\"wp-block-list\">\n<li>Wi-Fi can be switched on or off without restarting the meter, via the menu or the website<\/li>\n<li>In LOW_POWER mode, Wi-Fi connects only every N wake cycles (configurable) to save battery life<\/li>\n<li>If you\u2019re using MQTT, you need to have Wi-Fi switched on<\/li>\n<li>CO2 Gadget supports <strong>2.4 GHz networks<\/strong> (the ESP32 does not support 5 GHz)<\/li>\n<\/ul>\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n<p class=\"wp-block-paragraph\"><em>Do you also check the <a href=\"https:\/\/emariete.com\/en\/co2-gadget-guide-menu\/\">Menu Guide<\/a>. Any questions? Ask on the <a href=\"https:\/\/t.me\/emariete_chat\">Telegram group<\/a> or open a <a href=\"https:\/\/github.com\/melkati\/CO2-Gadget\/issues\">issue on GitHub<\/a>.<\/em><\/p>\n<div class=\"essb_break_scroll\"><\/div>","protected":false},"excerpt":{"rendered":"<p>CO2 Gadget WiFi Guide. Learn how to connect your high-quality CO\u2082 monitor to the network: captive portal, MyAmbiance app, web interface, REST API, mDNS, static IP and troubleshooting. CO2 Gadget, the firmware that turns your ESP32 into a professional CO\u2082 monitor.<\/p>","protected":false},"author":1,"featured_media":243261,"comment_status":"open","ping_status":"","sticky":false,"template":"","format":"standard","meta":{"_uag_custom_page_level_css":"","_lmt_disableupdate":"","_lmt_disable":"","footnotes":""},"categories":[13,16],"tags":[24,71,27],"class_list":["post-243020","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-co2-gadget","category-medidor-co2","tag-co2-gadget","tag-co2-gadget-guias","tag-esp32"],"modified_by":null,"uagb_featured_image_src":{"full":["https:\/\/emariete.com\/wp-content\/uploads\/2026\/07\/Blue_banner_with_white_text_202607050739.jpeg",1376,768,false],"thumbnail":["https:\/\/emariete.com\/wp-content\/uploads\/2026\/07\/Blue_banner_with_white_text_202607050739-150x150.jpeg",150,150,true],"medium":["https:\/\/emariete.com\/wp-content\/uploads\/2026\/07\/Blue_banner_with_white_text_202607050739-300x167.jpeg",300,167,true],"medium_large":["https:\/\/emariete.com\/wp-content\/uploads\/2026\/07\/Blue_banner_with_white_text_202607050739-768x429.jpeg",768,429,true],"large":["https:\/\/emariete.com\/wp-content\/uploads\/2026\/07\/Blue_banner_with_white_text_202607050739-1024x572.jpeg",1024,572,true],"1536x1536":["https:\/\/emariete.com\/wp-content\/uploads\/2026\/07\/Blue_banner_with_white_text_202607050739.jpeg",1376,768,false],"2048x2048":["https:\/\/emariete.com\/wp-content\/uploads\/2026\/07\/Blue_banner_with_white_text_202607050739.jpeg",1376,768,false],"trp-custom-language-flag":["https:\/\/emariete.com\/wp-content\/uploads\/2026\/07\/Blue_banner_with_white_text_202607050739-18x10.jpeg",18,10,true]},"uagb_author_info":{"display_name":"Mariete","author_link":"https:\/\/emariete.com\/en\/author\/admin_xlyz052h\/"},"uagb_comment_info":0,"uagb_excerpt":"Gu\u00eda WiFi de CO2 Gadget. Aprende a conectar tu medidor de CO\u2082 de alta calidad a la red: portal cautivo, App MyAmbiance, interfaz web, API REST, mDNS, IP fija y soluci\u00f3n de problemas. CO2 Gadget, el firmware que convierte tu ESP32 en un medidor de CO\u2082 profesional.","_links":{"self":[{"href":"https:\/\/emariete.com\/en\/wp-json\/wp\/v2\/posts\/243020","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/emariete.com\/en\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/emariete.com\/en\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/emariete.com\/en\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/emariete.com\/en\/wp-json\/wp\/v2\/comments?post=243020"}],"version-history":[{"count":13,"href":"https:\/\/emariete.com\/en\/wp-json\/wp\/v2\/posts\/243020\/revisions"}],"predecessor-version":[{"id":243280,"href":"https:\/\/emariete.com\/en\/wp-json\/wp\/v2\/posts\/243020\/revisions\/243280"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/emariete.com\/en\/wp-json\/wp\/v2\/media\/243261"}],"wp:attachment":[{"href":"https:\/\/emariete.com\/en\/wp-json\/wp\/v2\/media?parent=243020"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/emariete.com\/en\/wp-json\/wp\/v2\/categories?post=243020"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/emariete.com\/en\/wp-json\/wp\/v2\/tags?post=243020"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}