bertmelis/esp32DHT

DHT library for ESP32 using the RMT peripheral

esp32DHT

This is a DHT11/22 library for ESP32 using the RMT peripheral, for use in the Arduino framework.
For ESP8266, please look into this repo: DHT

The library is non blocking and is usable in async frameworks. Time consuming methods are offloaded to a separate task. The library is kept simple on purpose. You are responsible yourself to follow the sensor's constraints (like polling frequency) and logical programming errors. Supplementary functions like dew point calculation are not included.

Installation

• For Arduino IDE: see the Arduino Guide
• For Platformio: see the Platfomio guide

Usage

#include <Arduino.h>
#include <esp32DHT.h>

DHT22 sensor;

void setup() {
  Serial.begin(112500);
  sensor.setup(23);  // optionally use another RMT channel: sensor.setup(23, RMT_CHANNEL_2);
  sensor.onData([](float humid, float temp) {
    Serial.printf("Temp: %.1f°C\nHumid: %.1f%%\n", temp, humid);
  });
  sensor.onError([](uint8_t error) {
    Serial.printf("Error: %d-%s\n", error, sensor.getError());
  });
}

void loop() {
  static uint32_t lastMillis = 0;
  if (millis() - lastMillis > 30000) {
      lastMillis = millis();
      sensor.read();
      Serial.print("Read DHT...\n");
  }
}

Note: setup(uint8_t, rmt_channel_t channel = RMT_CHANNEL_0); takes 2 arguments: the pin connected to the DHT sensor and the RMT channel[0-7]. The library uses 2 channels and defaults to (starting) channel 0. This means that by default channel 0 and channel 1 are occupied by the DHT and you should not use channel 7. If you're also using other RMT channels (for IR devices, extra DHT sensors, Neopixels...) you have to keep this in mind.

Read more about RMT in the docs: ESP-IDF documentation

Known issues

• When reading out the sensor for the first time after powerup, the lib returns an "UNDERFLOW" error. The next readings will be correct.
• Use the issue tracker if you encounter any other problems.

History

Whatever can be done using hardware should not be done by software. ESP32 has a RMT peripheral device which is remarkably versatile. As the DHT sensors rely on tight timing, the RMT device is perfect to accomplish reliable communication. I didn't find any other Arduino library that uses the RMT and/or doesn't block during communication. So I created my own one.

This library won't exist without the examples for RMT. Credits go to the team and contributors of ESP-IDF and @nkolban!