\/* Project ESP32, DHT, MQTT and Deepsleep *\/\r\n#include <WiFi.h>\r\n#include <PubSubClient.h>\r\n#include \"DHT.h\" \/\/ Library for DHT sensors\r\n\r\n#define wifi_ssid \"My_APs_ssid\" \/\/wifi ssid\r\n#define wifi_password \"my_password\" \/\/wifi password\r\n\r\n#define mqtt_server \"mqtt_broker_IP\" \/\/ server name or IP\r\n#define mqtt_user \"username\" \/\/ username\r\n#define mqtt_password \"password\" \/\/ password\r\n\r\n#define temperature_topic \"topic\/temp1\" \/\/Topic temperature\r\n#define humidity_topic \"topic\/humid1\" \/\/Topic humidity\r\n#define debug_topic \"debug\" \/\/Topic for debugging\r\n\r\n\/* definitions for deepsleep *\/\r\n#define uS_TO_S_FACTOR 1000000 \/* Conversion factor for micro seconds to seconds *\/\r\n#define TIME_TO_SLEEP 900 \/* Time ESP32 will go to sleep for 15 minutes (in seconds) *\/\r\n#define TIME_TO_SLEEP_ERROR 3600 \/* Time to sleep in case of error (1 hour) *\/\r\n\r\nbool debug = true; \/\/Display log message if True\r\n\r\n#define DHTPIN 14 \/\/ DHT Pin \r\n\/\/ Uncomment depending on your sensor type:\r\n#define DHTTYPE DHT11 \/\/ DHT 11 \r\n\/\/#define DHTTYPE DHT22 \/\/ DHT 22 (AM2302)\r\n\r\n\/\/ Create objects\r\nDHT dht(DHTPIN, DHTTYPE); \r\nWiFiClient espClient;\r\nPubSubClient client(espClient);\r\n\r\nvoid setup() {\r\n Serial.begin(115200); \r\n setup_wifi(); \/\/Connect to Wifi network\r\n \r\n client.setServer(mqtt_server, 1883); \/\/ Configure MQTT connection, change port if needed.\r\n\r\n if (!client.connected()) {\r\n reconnect();\r\n }\r\n dht.begin();\r\n \r\n \/\/ Read temperature in Celcius\r\n float t = dht.readTemperature();\r\n \/\/ Read humidity\r\n float h = dht.readHumidity();\r\n \r\n\r\n \/\/ Nothing to send. Warn on MQTT debug_topic and then go to sleep for longer period.\r\n if ( isnan(t) || isnan(h)) {\r\n Serial.println(\"[ERROR] Please check the DHT sensor !\");\r\n client.publish(debug_topic, \"[ERROR] Please check the DHT sensor !\", true); \/\/ Publish humidity on broker\/humid1\r\n esp_sleep_enable_timer_wakeup(TIME_TO_SLEEP * uS_TO_S_FACTOR); \/\/go to sleep\r\n Serial.println(\"Setup ESP32 to sleep for every \" + String(TIME_TO_SLEEP) + \" Seconds\");\r\n Serial.println(\"Going to sleep now because of ERROR\");\r\n esp_deep_sleep_start();\r\n return;\r\n }\r\n \r\n if ( debug ) {\r\n Serial.print(\"Temperature : \");\r\n Serial.print(t);\r\n Serial.print(\" | Humidity : \");\r\n Serial.println(h);\r\n } \r\n \/\/ Publish values to MQTT topics\r\n client.publish(temperature_topic, String(t).c_str(), true); \/\/ Publish temperature on broker\/temp1\r\n if ( debug ) { \r\n Serial.println(\"Temperature sent to MQTT.\");\r\n }\r\n delay(100); \/\/some delay is needed for the mqtt server to accept the message\r\n client.publish(humidity_topic, String(h).c_str(), true); \/\/ Publish humidity on broker\/humid1\r\n if ( debug ) {\r\n Serial.println(\"Humidity sent to MQTT.\");\r\n } \r\n\r\n esp_sleep_enable_timer_wakeup(TIME_TO_SLEEP * uS_TO_S_FACTOR); \/\/go to sleep\r\n Serial.println(\"Setup ESP32 to sleep for every \" + String(TIME_TO_SLEEP) + \" Seconds\");\r\n Serial.println(\"Going to sleep as normal now.\");\r\n esp_deep_sleep_start();\r\n}\r\n\r\n\/\/Setup connection to wifi\r\nvoid setup_wifi() {\r\n delay(20);\r\n Serial.println();\r\n Serial.print(\"Connecting to \");\r\n Serial.println(wifi_ssid);\r\n\r\n WiFi.begin(wifi_ssid, wifi_password);\r\n\r\n while (WiFi.status() != WL_CONNECTED) {\r\n delay(100);\r\n Serial.print(\".\");\r\n }\r\n\r\n Serial.println(\"\");\r\n Serial.println(\"WiFi is OK \");\r\n Serial.print(\"=> ESP32 new IP address is: \");\r\n Serial.print(WiFi.localIP());\r\n Serial.println(\"\");\r\n}\r\n\r\n\/\/Reconnect to wifi if connection is lost\r\nvoid reconnect() {\r\n\r\n while (!client.connected()) {\r\n Serial.print(\"Connecting to MQTT broker ...\");\r\n if (client.connect(\"ESP32Client\", mqtt_user, mqtt_password)) {\r\n Serial.println(\"OK\");\r\n } else {\r\n Serial.print(\"[Error] Not connected: \");\r\n Serial.print(client.state());\r\n Serial.println(\"Wait 5 seconds before retry.\");\r\n delay(5000);\r\n }\r\n }\r\n}\r\n\r\nvoid loop() { \r\n}<\/pre>\n

Here is an example of how I post humidity and temperature values that I collect from a DHT11 sensor. I use an ESP32 (Lolin32) board and I post values to a MQTT open source message broker (Eclipse Mosquitto) that I run alongside openhab on a Rpi3. Finally, I deep sleep the board to save energy. I use the following libraries: Arduino library for DHT11\/DHT22 by Adafruit [>>] Arduino Client for MQTT (PubSubClient) by Nick O’Leary [>>] Arduino core for ESP32 WiFi chip [>>] To install CP210x Driver v10.1.1 for Lolin32 ESP32 there installation issue with Windows 10, build 1803. Check this post: [>>] \/* Project ESP32, DHT, MQTT and Deepsleep *\/ #include <WiFi.h> #include <PubSubClient.h> #include “DHT.h” \/\/ Library for DHT sensors #define wifi_ssid “My_APs_ssid” \/\/wifi ssid #define wifi_password “my_password” \/\/wifi password #define mqtt_server “mqtt_broker_IP” \/\/ server name or IP #define mqtt_user “username” \/\/ username #define mqtt_password “password” \/\/ password #define temperature_topic […]<\/p>\n","protected":false},"author":1,"featured_media":6872,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"inline_featured_image":false,"ngg_post_thumbnail":0,"jetpack_post_was_ever_published":false,"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[682,730,729],"tags":[781,780,774,777,779],"class_list":["post-6862","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-arduino","category-esp32","category-espressif","tag-deep-sleep","tag-dht","tag-esp32","tag-openhab","tag-openhab2"],"aioseo_notices":[],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/xylem.aegean.gr\/~modestos\/mo.blog\/wp-content\/uploads\/2018\/05\/IMG_20180514_024610.jpg?fit=4160%2C3120&ssl=1","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/pzkzw-1MG","jetpack_likes_enabled":true,"jetpack-related-posts":[],"_links":{"self":[{"href":"https:\/\/xylem.aegean.gr\/~modestos\/mo.blog\/wp-json\/wp\/v2\/posts\/6862","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/xylem.aegean.gr\/~modestos\/mo.blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/xylem.aegean.gr\/~modestos\/mo.blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/xylem.aegean.gr\/~modestos\/mo.blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/xylem.aegean.gr\/~modestos\/mo.blog\/wp-json\/wp\/v2\/comments?post=6862"}],"version-history":[{"count":11,"href":"https:\/\/xylem.aegean.gr\/~modestos\/mo.blog\/wp-json\/wp\/v2\/posts\/6862\/revisions"}],"predecessor-version":[{"id":7187,"href":"https:\/\/xylem.aegean.gr\/~modestos\/mo.blog\/wp-json\/wp\/v2\/posts\/6862\/revisions\/7187"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/xylem.aegean.gr\/~modestos\/mo.blog\/wp-json\/wp\/v2\/media\/6872"}],"wp:attachment":[{"href":"https:\/\/xylem.aegean.gr\/~modestos\/mo.blog\/wp-json\/wp\/v2\/media?parent=6862"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/xylem.aegean.gr\/~modestos\/mo.blog\/wp-json\/wp\/v2\/categories?post=6862"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/xylem.aegean.gr\/~modestos\/mo.blog\/wp-json\/wp\/v2\/tags?post=6862"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}