pyttroll/go-dht

DHTxx temperature and humidity sensors

DHT11 ([pdf reference](https://raw.github.com/d2r2/go-dht/master/docs/DHT11 (1).pdf)) and DHT22 (pdf reference) sensors are quite popular among Arduino, Raspberry PI and their counterparts developers (here you will find comparision DHT11 vs DHT22):

They are cheap enough and affordable. So, here is a code written in Go programming language for Raspberry PI and counterparts, which gives you at the output temperature and humidity values (making all necessary signal processing via their own 1-wire bus protocol behind the scene).

Compatibility

Tested on Raspberry PI 1 (model B) and Banana PI (model M1).

Golang usage

func main() {
	// Read DHT11 sensor data from pin 4, retrying 10 times in case of failure.
	// You may enable "boost GPIO performance" parameter, if your device is old
	// as Raspberry PI 1 (this will require root privileges). You can switch off
	// "boost GPIO performance" parameter for old devices, but it may increase
	// retry attempts. Play with this parameter.
	temperature, humidity, retried, err :=
		dht.ReadDHTxxWithRetry(dht.DHT11, 4, true, 10)
	if err != nil {
		log.Fatal(err)
	}
	// Print temperature and humidity
	fmt.Printf("Temperature = %v*C, Humidity = %v%% (retried %d times)\n",
		temperature, humidity, retried)
}

Getting help

GoDoc documentation.

For detailed explanation read great article "Golang with Raspberry Pi : Read RH and Temperature from DHT22 or AM2302" written by Joseph Mathew. Thanks Joseph!

Installation

$ go get -u github.com/d2r2/go-dht

Quick tutorial

There are two functions you could use: ReadDHTxx(...) and ReadDHTxxWithRetry(...). They both do exactly same thing - activate sensor then read and decode temperature and humidity values. The only thing which distinguish one from another - "retry count" parameter as additinal argument in ReadDHTxxWithRetry(...). So, it's highly recomended to utilize ReadDHTxxWithRetry(...) with "retry count" not less than 7, since sensor asynchronouse protocol is not very stable causing errors time to time. Each additinal retry attempt takes 1.5-2 seconds (according to specification before repeated attempt you should wait 1-2 seconds).

This functionality works not only with Raspberry PI, but with counterparts as well (tested with Raspberry PI and Banana PI).

Note: If you enable "boost GPIO performance" parameter, application should run with root privileges, since C code inside requires this. In most cases it is sufficient to add "sudo -E" before "go run ...".

Note: This package does not require any external C code or library.

License

Go-dht is licensed under MIT License.

pyttroll / go-dht