Log DHT Temperature sensor data over serial using an Arduino

So far, this has only been tested with DHT22 temperature sensors.

See the .gitmodules file for the Arduino library dependencies.

This logs temperature, humidity, and heat index over JSON. Each sensor is enumerated in the json according to the pin number that it is connected to. The JSON data for each pin is represented as t for temperature, h for humidity, and hi for heat index, or e for error. All values are in Celcius.

The following code imports the DHT logger library and creates a logger object that uses pins 2 and 4 as sensors and enables power over pin 8. It then logs the temperature data over the Serial interface.

#include "dht_logger.h"

// Pin arrays must have 0 as the last element or else this will panic. Future
// revisions of this library will make that no longer necessary.
constexpr uint8_t kPowerPins[] = {8, 0};
constexpr uint8_t kSensorPins[] = {2, 4, 0};

// Create a logger object that logs DHT22 pins over Serial
dht::DhtLogger logger(kSensorPins, DHT22, &Serial, kPowerPins);

void setup() {
  // Note that Serial.begin() is not done from within logger.begin(). The
  // serial interface must be explicitly initialized somewhere before the
  // logger can begin.
  Serial.begin(115200);
  logger.begin();
}

void loop() {
  // This reads measurements and writes them over serial in JSON format.
  delay(logger.writeToSerial());
}

To use the standalone method on Ubuntu, install the arduino-mk package. The standalone method is currently only supported on Ubuntu 20.04 and Raspbian Buster, but may work on other OS configurations.

The standalone method generates an Arduino firmware binary based on a config file. The config file is in JSON format. See example_config.json for an example of a valid config file with every option used. The serial and power_pins keys in the config are optional. All other keys listed in example_config.json are required.

Configuration binaries can be built and flashed to Arduino devices as follows:

python3 build.py -c example_config.json -p /dev/ttyUSB0