Embedded sensing + wireless serial
Bluetooth temperature and humidity link
A DHT11 sensor supplies temperature and humidity readings to a Bluetooth serial link. The firmware checks the measurements before formatting them for an HC-05 receiver.
Engineering scope
- DHT11 temperature and humidity acquisition
- Invalid-reading handling
- Formatting and transmission over Bluetooth serial
Firmware flow
How a temperature reading reaches Bluetooth
Complete temperature and humidity transmission routine.
Read temperature and humidity. If either reading is invalid, send a sensor-read error and stop. Otherwise format the values and send them through the HC-05 serial interface.
This establishes the packet-building logic, not wireless range, delivery confirmation or sensor accuracy.
Read the implementation
sendDHT11Data · selected source lines 187–206. Source inspection is not a hardware test.
void sendDHT11Data() {
float humidity = dht.readHumidity();
float temperatureC = dht.readTemperature();
if (isnan(humidity) || isnan(temperatureC)) {
Serial.println("DHT11 read failed.");
hc05.println("ERROR,DHT11_READ_FAILED");
return;
}
String dataPacket = "";
dataPacket += "TEMP_C=";
dataPacket += temperatureC;
dataPacket += ",HUMIDITY=";
dataPacket += humidity;
Serial.println(dataPacket);
hc05.println(dataPacket);
}Invalid-reading handling
The send function reads temperature and humidity, then checks both values. If either read fails, it sends DHT11_READ_FAILED and returns without formatting a numeric result.
Serial message formatting
For valid measurements, the function builds a temperature-and-humidity message and writes it to the HC-05 serial connection. The complete function is included below.
Source implementation
The excerpt documents acquisition, validation, formatting and transmission. It does not establish sensor accuracy, hardware endurance or production validation.
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