sparkfun / sparkfun_rht03_particle_library

Firmware library for the SparkFun RHT03 humidity and temperature sensor.

SparkFun RHT03 Particle Library

A firmware library for the SparkFun's RHT03 humidity and temperaure sensor.

About

The RHT03 is a one-wire digital sensor that measures relative humidity from 0-100% and temperature from -40-80 deg C.

Repository Contents

• /firmware - Source files for the library (.cpp, .h).
• /firmware/examples - Example sketches for the library (.cpp). Run these from the Particle IDE.
• spark.json - General library properties for the Particle library manager.

Example Usage

Create an RHT03 Object & Initialize

To begin, create an RHT03 class object. This'll often go in the global section of the code:

///////////////////////////
// RHT03 Object Creation //
///////////////////////////
RHT03 rht; // This creates a RTH03 object, which we'll use to interact with the sensor

To initialize the sensor, call the begin([pin]) function, where [pin] is the Photon pin connected to the RHT03 data pin.

void setup()
{
	...
	rht.begin(D3); // Initialize an RHT03 sensor, with the data pin connected to D3.
	...
}

Update and Read Humidity and Temp Values

Temperature and humidity values are updated in one fell single-wire swoop. To get new values from the sensor, call update(). update() returns either 1 on success, or a negative value if it fails.

int updateRet = rht.update();

If the update succeeds, use the humidity(), tempC(), and tempF() functions to get relative humidity, celsius, and farenheit temperatures. All variables are returned as float's.

if (updateRet == 1)
{
	float rh = rht.humidity();
	float tf = rht.tempF();
	float tc = rht.tempC();
}

Recommended Components

• RHT03 Humidity & Temperature Sensor
• Particle Photon or SparkFun Photon RedBoard

License Information

This product is open source!

Please review the LICENSE.md file for license information.

If you have any questions or concerns on licensing, please contact [email protected].

Distributed as-is; no warranty is given.

• Your friends at SparkFun.

sparkfun_rht03_particle_library's Issues

Temperatures below 0°C are rolling over

This code

"\"RHT03\":{" +
   "\"T\":" + String(rht.tempC(), 2) + "," +
   "\"H\":" + String(rht.humidity(), 2) + 
"}," +

is creating this result

"RHT03":{"T":3279.80,"H":83.30}

These where all the readings on the same board during that fetch:

{"BME280":{"T":-1.88,"H":84.75,"P":1023.99},
 "RHT03":{"T":3279.80,"H":83.30},
 "DS18B20":{
   "28CEB45204000083":{"T":-3.19,"C":1},
   "28646952040000A2":{"T":-3.19,"C":1}
 },
 "A0":{"L":2.50}
}

I consider the DS18B20's temperature readings to be the "most precise"

Does not return correct values for new Particle mesh devices.

When using the RHT03 sensor and this library for the new Particle Mesh devices, the return values are not consistent. There is a thread in the Particle community forums about the issue here:

https://community.particle.io/t/incorrect-data-output-with-rht03-temp-humidity-sensor-using-argon-solved-but-now-using-dht11/46808

It is possible that the use of noInterrupts() and interrupts() may cause unintended problems with timing on the Mesh devices.

Compile errors when using Particle Build

There are two code issues in this library source that result in compilation errors if copy/pasted in to the Particle Build cloud IDE. I am not familiar enough with the Particle ecosystem and history to understand if/how this worked previously.

Compile errors:

src/SparkFunRHT03.cpp:119:28: error: 'CHECKSUM' was not declared in this scope
     if (checksum(dataBytes[CHECKSUM], dataBytes, 4))
                            ^
src/SparkFunRHT03.cpp:121:48: error: 'HUMIDITY_H' was not declared in this scope
   _humidity = (static_cast<uint16_t>(dataBytes[HUMIDITY_H] << 8) | dataBytes[HUMIDITY_L]);
                                                ^
src/SparkFunRHT03.cpp:121:78: error: 'HUMIDITY_L' was not declared in this scope
   _humidity = (static_cast<uint16_t>(dataBytes[HUMIDITY_H] << 8) | dataBytes[HUMIDITY_L]);
                                                                              ^
src/SparkFunRHT03.cpp:122:52: error: 'TEMP_H' was not declared in this scope
   _temperature = static_cast<uint16_t> ((dataBytes[TEMP_H] << 8) | dataBytes[TEMP_L]);
                                                    ^
src/SparkFunRHT03.cpp:122:78: error: 'TEMP_L' was not declared in this scope
   _temperature = static_cast<uint16_t> ((dataBytes[TEMP_H] << 8) | dataBytes[TEMP_L]);
                                                                              ^
src/SparkFunRHT03.cpp:131:6: error:
prototype for 'bool RHT03::checksum(byte, const byte*, unsigned int)' 
does not match any in class 'RHT03'
 bool RHT03::checksum(const byte check, const byte * data, const unsigned int datalen)
      
src/SparkFunRHT03.cpp:35:7: error: candidate is: bool RHT03::checksum(byte, byte*, unsigned int)
  bool checksum(byte check, byte * data, const unsigned int datalen);