A confusing issue with NodeMCU

This page summarizes the projects mentioned and recommended in the original post on reddit.com/r/arduino

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  • GitHub repo DHT-sensor-library

    Arduino library for DHT11, DHT22, etc Temperature & Humidity Sensors

    // Example testing sketch for various DHT humidity/temperature sensors // Written by ladyada, public domain // REQUIRES the following Arduino libraries: // - DHT Sensor Library: https://github.com/adafruit/DHT-sensor-library // - Adafruit Unified Sensor Lib: https://github.com/adafruit/Adafruit_Sensor #include "DHT.h" #define DHTPIN 4 // Digital pin connected to the DHT sensor // Feather HUZZAH ESP8266 note: use pins 3, 4, 5, 12, 13 or 14 -- // Pin 15 can work but DHT must be disconnected during program upload. // Uncomment whatever type you're using! #define DHTTYPE DHT11 // DHT 11 //#define DHTTYPE DHT22 // DHT 22 (AM2302), AM2321 //#define DHTTYPE DHT21 // DHT 21 (AM2301) // Connect pin 1 (on the left) of the sensor to +5V // NOTE: If using a board with 3.3V logic like an Arduino Due connect pin 1 // to 3.3V instead of 5V! // Connect pin 2 of the sensor to whatever your DHTPIN is // Connect pin 3 (on the right) of the sensor to GROUND (if your sensor has 3 pins) // Connect pin 4 (on the right) of the sensor to GROUND and leave the pin 3 EMPTY (if your sensor has 4 pins) // Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor // Initialize DHT sensor. // Note that older versions of this library took an optional third parameter to // tweak the timings for faster processors. This parameter is no longer needed // as the current DHT reading algorithm adjusts itself to work on faster procs. DHT dht(DHTPIN, DHTTYPE); void setup() { delay(2000); Serial.begin(115200); delay(2000); Serial.println(F("DHTxx test!")); dht.begin(); } void loop() { // Wait a few seconds between measurements. delay(2000); // Reading temperature or humidity takes about 250 milliseconds! // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor) float h = dht.readHumidity(); // Read temperature as Celsius (the default) float t = dht.readTemperature(); // Read temperature as Fahrenheit (isFahrenheit = true) float f = dht.readTemperature(true); // Check if any reads failed and exit early (to try again). if (isnan(h) || isnan(t) || isnan(f)) { Serial.println(F("Failed to read from DHT sensor!")); return; } // Compute heat index in Fahrenheit (the default) float hif = dht.computeHeatIndex(f, h); // Compute heat index in Celsius (isFahreheit = false) float hic = dht.computeHeatIndex(t, h, false); Serial.print(F("Humidity: ")); Serial.print(h); Serial.print(F("% Temperature: ")); Serial.print(t); Serial.print(F("°C ")); Serial.print(f); Serial.print(F("°F Heat index: ")); Serial.print(hic); Serial.print(F("°C ")); Serial.print(hif); Serial.println(F("°F")); }

  • GitHub repo Adafruit_Sensor

    Common sensor library

    // Example testing sketch for various DHT humidity/temperature sensors // Written by ladyada, public domain // REQUIRES the following Arduino libraries: // - DHT Sensor Library: https://github.com/adafruit/DHT-sensor-library // - Adafruit Unified Sensor Lib: https://github.com/adafruit/Adafruit_Sensor #include "DHT.h" #define DHTPIN 4 // Digital pin connected to the DHT sensor // Feather HUZZAH ESP8266 note: use pins 3, 4, 5, 12, 13 or 14 -- // Pin 15 can work but DHT must be disconnected during program upload. // Uncomment whatever type you're using! #define DHTTYPE DHT11 // DHT 11 //#define DHTTYPE DHT22 // DHT 22 (AM2302), AM2321 //#define DHTTYPE DHT21 // DHT 21 (AM2301) // Connect pin 1 (on the left) of the sensor to +5V // NOTE: If using a board with 3.3V logic like an Arduino Due connect pin 1 // to 3.3V instead of 5V! // Connect pin 2 of the sensor to whatever your DHTPIN is // Connect pin 3 (on the right) of the sensor to GROUND (if your sensor has 3 pins) // Connect pin 4 (on the right) of the sensor to GROUND and leave the pin 3 EMPTY (if your sensor has 4 pins) // Connect a 10K resistor from pin 2 (data) to pin 1 (power) of the sensor // Initialize DHT sensor. // Note that older versions of this library took an optional third parameter to // tweak the timings for faster processors. This parameter is no longer needed // as the current DHT reading algorithm adjusts itself to work on faster procs. DHT dht(DHTPIN, DHTTYPE); void setup() { delay(2000); Serial.begin(115200); delay(2000); Serial.println(F("DHTxx test!")); dht.begin(); } void loop() { // Wait a few seconds between measurements. delay(2000); // Reading temperature or humidity takes about 250 milliseconds! // Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor) float h = dht.readHumidity(); // Read temperature as Celsius (the default) float t = dht.readTemperature(); // Read temperature as Fahrenheit (isFahrenheit = true) float f = dht.readTemperature(true); // Check if any reads failed and exit early (to try again). if (isnan(h) || isnan(t) || isnan(f)) { Serial.println(F("Failed to read from DHT sensor!")); return; } // Compute heat index in Fahrenheit (the default) float hif = dht.computeHeatIndex(f, h); // Compute heat index in Celsius (isFahreheit = false) float hic = dht.computeHeatIndex(t, h, false); Serial.print(F("Humidity: ")); Serial.print(h); Serial.print(F("% Temperature: ")); Serial.print(t); Serial.print(F("°C ")); Serial.print(f); Serial.print(F("°F Heat index: ")); Serial.print(hic); Serial.print(F("°C ")); Serial.print(hif); Serial.println(F("°F")); }

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NOTE: The number of mentions on this list indicates mentions on common posts plus user suggested alternatives. Hence, a higher number means a more popular project.

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