DHT Family of Humidity and Temperature Sensors

Device driver for the DHT Family of humidity and temperature sensors. More...

Detailed Description

Device driver for the DHT Family of humidity and temperature sensors.

This driver provides [S]ensor [A]ctuator [U]ber [L]ayer capabilities.

Files
file	dht_params.h
	Default configuration for DHT devices.
file	dht.h
	Device driver interface for the DHT family of humidity and temperature sensors.

Data Structures
struct	dht_data_t
	Data type for storing DHT sensor readings. More...
struct	dht_params_t
	Configuration parameters for DHT devices. More...
struct	dht_t
	Device descriptor for DHT sensor devices. More...

Enumerations
enum	{ DHT_OK = 0, DHT_NOCSUM = -1, DHT_TIMEOUT = -2, DHT_NODEV = -3 }
	Possible return codes. More...
enum	dht_type_t { DHT11, DHT22, DHT21 = DHT22 }
	Device type of the DHT device. More...

Functions
int	dht_init (dht_t *dev, const dht_params_t *params)
	Initialize a new DHT device. More...
int	dht_read (dht_t *dev, int16_t *temp, int16_t *hum)
	get a new temperature and humidity value from the device More...

Enumeration Type Documentation

anonymous enum

anonymous enum

Possible return codes.

Enumerator
DHT_OK	all good
DHT_NOCSUM	checksum error
DHT_TIMEOUT	communication timed out
DHT_NODEV	device type not defined

Definition at line 45 of file dht.h.

dht_type_t

enum dht_type_t

Device type of the DHT device.

Enumerator
DHT11	DHT11 device identifier.
DHT22	DHT22 device identifier.
DHT21	DHT21 device identifier.

Definition at line 63 of file dht.h.

Function Documentation

dht_init()

int dht_init	(	dht_t *	dev,
		const dht_params_t *	params
	)

Initialize a new DHT device.

Parameters

[out]	dev	device descriptor of a DHT device
[in]	params	configuration parameters

Returns

0 on success

-1 on error

dht_read()

int dht_read	(	dht_t *	dev,
		int16_t *	temp,
		int16_t *	hum
	)

get a new temperature and humidity value from the device

Note

if reading fails or checksum is invalid, no new values will be written into the result values

Parameters

[in]	dev	device descriptor of a DHT device
[out]	temp	temperature value [in °C * 10^-1]
[out]	hum	relative humidity value [in percent * 10^-1]

Return values

DHT_OK	Success
DHT_NOCSUM	Checksum error
DHT_TIMEOUT	Reading data timed out (check wires!)
DHT_NODEV	Unsupported device type specified