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SendDHTSerialData.ino
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SendDHTSerialData.ino
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#include <ArduinoJson.h>
#include <DHT.h>
constexpr uint8_t dhtPin = 2; // Pin connected to the DHT sensor.
constexpr uint8_t dhtType = DHT22; // Use DHT 22 (AM2302)
DHT dht{dhtPin, dhtType};
void setup() {
Serial.begin(9600);
dht.begin();
}
void loop() {
// Wait 5 seconds between measurements.
// Reading temperature or humidity takes about 250 milliseconds!
// Sensor readings may also be up to 2 seconds 'old' (its a very slow sensor)
delay(5000);
// Memory pool for JSON object tree.
// Inside the brackets, 200 is the size of the pool in bytes.
StaticJsonBuffer<200> jsonBuffer;
// It's a reference to the JsonObject, the actual bytes are inside the
// JsonBuffer with all the other nodes of the object tree.
// Memory is freed when jsonBuffer goes out of scope.
auto& root = jsonBuffer.createObject();
// Read temperature and set its value.
const auto temperature = dht.readTemperature();
if (isnan(temperature)) {
setError(root, "Error reading temperature!");
}
else {
root["temperature"] = temperature;
}
// Read humidity and set its value.
const auto humidity = dht.readHumidity();
if (isnan(humidity)) {
setError(root, "Error reading humidity!");
}
else {
root["humidity"] = humidity;
}
// Serialize Json.
root.printTo(Serial);
Serial.print("\n"); // Delimiter to use.
}
// Sets the error value at errors key.
void setError(JsonObject& obj, const String& message) {
auto& errors = obj.containsKey("errors")
? obj["errors"]
: obj.createNestedArray("errors");
auto& error = errors.createNestedObject();
error["message"] = message;
}