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improve sensor HAL documentation
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Change-Id: If2c1613902de6ed0e6cae8fe4755948c0f623bda
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@pixelflinger
pixelflinger committed Nov 8, 2011
1 parent 45065f9 commit e9eaf37
Showing 1 changed file with 42 additions and 49 deletions.
91 changes: 42 additions & 49 deletions include/hardware/sensors.h
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Expand Up @@ -118,8 +118,8 @@ __BEGIN_DECLS
* O: Origin (x=0,y=0,z=0)
*
*
* Orientation
* -----------
* SENSOR_TYPE_ORIENTATION
* -----------------------
*
* All values are angles in degrees.
*
Expand Down Expand Up @@ -155,8 +155,8 @@ __BEGIN_DECLS
* where the X axis is along the long side of the plane (tail to nose).
*
*
* Acceleration
* ------------
* SENSOR_TYPE_ACCELEROMETER
* -------------------------
*
* All values are in SI units (m/s^2) and measure the acceleration of the
* device minus the force of gravity.
Expand All @@ -182,17 +182,18 @@ __BEGIN_DECLS
* gravity (-9.81 m/s^2).
*
*
* Magnetic Field
* --------------
* SENSOR_TYPE_MAGNETIC_FIELD
* --------------------------
*
* All values are in micro-Tesla (uT) and measure the ambient magnetic
* field in the X, Y and Z axis.
*
* Magnetic Field sensors return sensor events for all 3 axes at a constant
* rate defined by setDelay().
*
* Gyroscope
* ---------
* SENSOR_TYPE_GYROSCOPE
* ---------------------
*
* All values are in radians/second and measure the rate of rotation
* around the X, Y and Z axis. The coordinate system is the same as is
* used for the acceleration sensor. Rotation is positive in the
Expand All @@ -204,8 +205,8 @@ __BEGIN_DECLS
* with the definition of roll given earlier.
* The range should at least be 17.45 rad/s (ie: ~1000 deg/s).
*
* Proximity
* ---------
* SENSOR_TYPE_PROXIMITY
* ----------------------
*
* The distance value is measured in centimeters. Note that some proximity
* sensors only support a binary "close" or "far" measurement. In this case,
Expand All @@ -215,49 +216,42 @@ __BEGIN_DECLS
* Proximity sensors report a value only when it changes and each time the
* sensor is enabled.
*
* Light
* -----
* SENSOR_TYPE_LIGHT
* -----------------
*
* The light sensor value is returned in SI lux units.
*
* Light sensors report a value only when it changes and each time the
* sensor is enabled.
*
* Pressure
* --------
* SENSOR_TYPE_PRESSURE
* --------------------
*
* The pressure sensor value is returned in hectopascal (hPa)
* The pressure sensor return the athmospheric pressure in hectopascal (hPa)
*
* Pressure sensors report events at a constant rate defined by setDelay().
*
* Gyro
* --------
* SENSOR_TYPE_GRAVITY
* -------------------
*
* The gyroscope sensor values are returned in degrees per second (dps)
* A gravity output indicates the direction of and magnitude of gravity in
* the devices's coordinates. On Earth, the magnitude is 9.8 m/s^2.
* Units are m/s^2. The coordinate system is the same as is used for the
* acceleration sensor. When the device is at rest, the output of the
* gravity sensor should be identical to that of the accelerometer.
*
* Gyroscope sensor report events at a constant rate defined by setDelay().
* SENSOR_TYPE_LINEAR_ACCELERATION
* --------------------------------
*
* Gravity
* -------
* A gravity output indicates the direction of and magnitude of gravity in the devices's
* coordinates. On Earth, the magnitude is 9.8. Units are m/s^2. The coordinate system
* is the same as is used for the acceleration sensor.
* When the device is at rest, the output of the gravity sensor should be identical
* to that of the accelerometer.
* Indicates the linear acceleration of the device in device coordinates,
* not including gravity.
* This output is essentially Acceleration - Gravity. Units are m/s^2.
* The coordinate system is the same as is used for the acceleration sensor.
*
* Linear Acceleration
* -------------------
* Indicates the linear acceleration of the device in device coordinates, not including gravity.
* This output is essentially Acceleration - Gravity. Units are m/s^2. The coordinate system is
* the same as is used for the acceleration sensor.
* The output of the accelerometer, gravity and linear-acceleration sensors must obey the
* following relation:
*
* acceleration = gravity + linear-acceleration
* SENSOR_TYPE_ROTATION_VECTOR
* ---------------------------
*
*
* Rotation Vector
* ---------------
* A rotation vector represents the orientation of the device as a combination
* of an angle and an axis, in which the device has rotated through an angle
* theta around an axis <x, y, z>. The three elements of the rotation vector
Expand Down Expand Up @@ -289,8 +283,8 @@ __BEGIN_DECLS
* sensors_event_t.data[3] = cos(theta/2)
*
*
* Relative Humidity
* -----------------
* SENSOR_TYPE_RELATIVE_HUMIDITY
* ------------------------------
*
* A relative humidity sensor measures relative ambient air humidity and
* returns a value in percent.
Expand All @@ -299,8 +293,8 @@ __BEGIN_DECLS
* time the sensor is enabled.
*
*
* Ambient Temperature
* -------------------
* SENSOR_TYPE_AMBIENT_TEMPERATURE
* -------------------------------
*
* The ambient (room) temperature in degree Celsius.
*
Expand Down Expand Up @@ -405,9 +399,10 @@ struct sensor_t {
const char* name;
/* vendor of the hardware part */
const char* vendor;
/* version of the hardware part + driver. The value of this field is
* left to the implementation and doesn't have to be monotonically
* increasing.
/* version of the hardware part + driver. The value of this field
* must increase when the driver is updated in a way that changes the
* output of this sensor. This is important for fused sensors when the
* fusion algorithm is updated.
*/
int version;
/* handle that identifies this sensors. This handle is used to activate
Expand Down Expand Up @@ -452,11 +447,9 @@ struct sensors_poll_device_t {
/**
* Set the delay between sensor events in nanoseconds for a given sensor.
*
* It is an error to set a delay inferior to the value defined by
* sensor_t::minDelay.
*
* If sensor_t::minDelay is zero, setDelay() returns an error if the
* requested delay is inferior to 1ms.
* If the requested value is less than sensor_t::minDelay, then it's
* silently clamped to sensor_t::minDelay unless sensor_t::minDelay is
* 0, in which case it is clamped to >= 1ms.
*
* @return 0 if successful, < 0 on error
*/
Expand Down

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