SensorTag 2.0 TI HDC1000 Sensor

Due to the time required for the sensor to startup, this driver is meant to be used in an asynchronous fashion. More...

Files
file	hdc-1000-sensor.c
	Driver for the Sensortag HDC sensor.
file	hdc-1000-sensor.h
	Header file for the Sensortag TI HDC1000 sensor.

Functions
static bool	sensor_init (void)
	Initialise the humidity sensor driver. More...
static void	start (void)
	Start measurement.
static bool	read_data ()
	Take readings from the sensor. More...
static void	convert (float *temp, float *hum)
	Convert raw data to temperature and humidity. More...
static int	value (int type)
	Returns a reading from the sensor. More...
static int	configure (int type, int enable)
	Configuration function for the HDC1000 sensor. More...
static int	status (int type)
	Returns the status of the sensor. More...

HDC1000 driver states
#define	HDC_1000_SENSOR_STATUS_DISABLED   0
	Not initialised.
#define	HDC_1000_SENSOR_STATUS_INITIALISED   1
	Initialised but idle.
#define	HDC_1000_SENSOR_STATUS_TAKING_READINGS   2
	Readings in progress.
#define	HDC_1000_SENSOR_STATUS_READINGS_READY   3
	Both readings ready.

Detailed Description

Due to the time required for the sensor to startup, this driver is meant to be used in an asynchronous fashion.

The caller must first activate the sensor by calling SENSORS_ACTIVATE(). This will trigger the sensor's startup sequence, but the call will not wait for it to complete so that the CPU can perform other tasks or drop to a low power mode. Once the sensor has taken readings, it will automatically go back to low power mode.

Once the sensor is stable, the driver will retrieve readings from the sensor and latch them. It will then generate a sensors_changed event.

The user can then retrieve readings by calling .value() and by passing either HDC_1000_SENSOR_TYPE_TEMP or HDC_1000_SENSOR_TYPE_HUMID as the argument. Multiple calls to value() will not trigger new readings, they will simply return the most recent latched values.

The user can query the sensor's status by calling .status()

To get a fresh reading, the user must trigger a new reading cycle by calling SENSORS_ACTIVATE().

Function Documentation

configure()

static int configure ( int  type, int  enable  )

static

Configuration function for the HDC1000 sensor.

Parameters

type	Activate, enable or disable the sensor. See below
enable	When type == SENSORS_HW_INIT we turn on the hardware When type == SENSORS_ACTIVE and enable==1 we enable the sensor When type == SENSORS_ACTIVE and enable==0 we disable the sensor

Definition at line 252 of file hdc-1000-sensor.c.

convert()

static void convert ( float *  temp, float *  hum  )

static

Convert raw data to temperature and humidity.

Parameters

temp	- converted temperature
hum	- converted humidity

Definition at line 186 of file hdc-1000-sensor.c.

read_data()

static bool read_data ( )

static

Take readings from the sensor.

Returns

true of I2C operations successful

Definition at line 157 of file hdc-1000-sensor.c.

sensor_init()

static bool sensor_init ( void  )

static

Initialise the humidity sensor driver.

Returns

True if I2C operation successful

Definition at line 123 of file hdc-1000-sensor.c.

status()

static int status ( int  type )

static

Returns the status of the sensor.

Parameters

type	SENSORS_ACTIVE or SENSORS_READY

Returns

One of the SENSOR_STATUS_xyz defines

Definition at line 289 of file hdc-1000-sensor.c.

value()

static int value ( int  type )

static

Returns a reading from the sensor.

Parameters

type	HDC_1000_SENSOR_TYPE_TEMP or HDC_1000_SENSOR_TYPE_HUMID

Returns

Temperature (centi degrees C) or Humidity (centi RH)

Definition at line 212 of file hdc-1000-sensor.c.