sensors.h revision c04e5f68905127ae4c1a0c17d225db9cebe66a07 
1/*
2 * Copyright (C) 2008 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ANDROID_SENSORS_INTERFACE_H
18#define ANDROID_SENSORS_INTERFACE_H
19
20#include <stdint.h>
21#include <sys/cdefs.h>
22#include <sys/types.h>
23
24#include <hardware/hardware.h>
25#include <cutils/native_handle.h>
26
27__BEGIN_DECLS
28
29/**
30 * The id of this module
31 */
32#define SENSORS_HARDWARE_MODULE_ID "sensors"
33
34/**
35 * Name of the sensors device to open
36 */
37#define SENSORS_HARDWARE_POLL       "poll"
38
39/**
40 * Handles must be higher than SENSORS_HANDLE_BASE and must be unique.
41 * A Handle identifies a given sensors. The handle is used to activate
42 * and/or deactivate sensors.
43 * In this version of the API there can only be 256 handles.
44 */
45#define SENSORS_HANDLE_BASE             0
46#define SENSORS_HANDLE_BITS             8
47#define SENSORS_HANDLE_COUNT            (1<<SENSORS_HANDLE_BITS)
48
49
50/**
51 * Sensor types
52 */
53#define SENSOR_TYPE_ACCELEROMETER       1
54#define SENSOR_TYPE_MAGNETIC_FIELD      2
55#define SENSOR_TYPE_ORIENTATION         3
56#define SENSOR_TYPE_GYROSCOPE           4
57#define SENSOR_TYPE_LIGHT               5
58#define SENSOR_TYPE_PRESSURE            6
59#define SENSOR_TYPE_TEMPERATURE         7
60#define SENSOR_TYPE_PROXIMITY           8
61#define SENSOR_TYPE_GRAVITY             9
62#define SENSOR_TYPE_LINEAR_ACCELERATION 10
63#define SENSOR_TYPE_ROTATION_VECTOR     11
64
65/**
66 * Values returned by the accelerometer in various locations in the universe.
67 * all values are in SI units (m/s^2)
68 */
69
70#define GRAVITY_SUN             (275.0f)
71#define GRAVITY_EARTH           (9.80665f)
72
73/** Maximum magnetic field on Earth's surface */
74#define MAGNETIC_FIELD_EARTH_MAX    (60.0f)
75
76/** Minimum magnetic field on Earth's surface */
77#define MAGNETIC_FIELD_EARTH_MIN    (30.0f)
78
79
80/**
81 * status of each sensor
82 */
83
84#define SENSOR_STATUS_UNRELIABLE        0
85#define SENSOR_STATUS_ACCURACY_LOW      1
86#define SENSOR_STATUS_ACCURACY_MEDIUM   2
87#define SENSOR_STATUS_ACCURACY_HIGH     3
88
89/**
90 * Definition of the axis
91 * ----------------------
92 *
93 * This API is relative to the screen of the device in its default orientation,
94 * that is, if the device can be used in portrait or landscape, this API
95 * is only relative to the NATURAL orientation of the screen. In other words,
96 * the axis are not swapped when the device's screen orientation changes.
97 * Higher level services /may/ perform this transformation.
98 *
99 *   x<0         x>0
100 *                ^
101 *                |
102 *    +-----------+-->  y>0
103 *    |           |
104 *    |           |
105 *    |           |
106 *    |           |   / z<0
107 *    |           |  /
108 *    |           | /
109 *    O-----------+/
110 *    |[]  [ ]  []/
111 *    +----------/+     y<0
112 *              /
113 *             /
114 *           |/ z>0 (toward the sky)
115 *
116 *    O: Origin (x=0,y=0,z=0)
117 *
118 *
119 * Orientation
120 * -----------
121 *
122 * All values are angles in degrees.
123 *
124 * Orientation sensors return sensor events for all 3 axes at a constant
125 * rate defined by setDelay().
126 *
127 * azimuth: angle between the magnetic north direction and the Y axis, around
128 *  the Z axis (0<=azimuth<360).
129 *      0=North, 90=East, 180=South, 270=West
130 *
131 * pitch: Rotation around X axis (-180<=pitch<=180), with positive values when
132 *  the z-axis moves toward the y-axis.
133 *
134 * roll: Rotation around Y axis (-90<=roll<=90), with positive values when
135 *  the x-axis moves towards the z-axis.
136 *
137 * Note: For historical reasons the roll angle is positive in the clockwise
138 *  direction (mathematically speaking, it should be positive in the
139 *  counter-clockwise direction):
140 *
141 *                Z
142 *                ^
143 *  (+roll)  .--> |
144 *          /     |
145 *         |      |  roll: rotation around Y axis
146 *     X <-------(.)
147 *                 Y
148 *       note that +Y == -roll
149 *
150 *
151 *
152 * Note: This definition is different from yaw, pitch and roll used in aviation
153 *  where the X axis is along the long side of the plane (tail to nose).
154 *
155 *
156 * Acceleration
157 * ------------
158 *
159 *  All values are in SI units (m/s^2) and measure the acceleration of the
160 *  device minus the force of gravity.
161 *
162 *  Acceleration sensors return sensor events for all 3 axes at a constant
163 *  rate defined by setDelay().
164 *
165 *  x: Acceleration minus Gx on the x-axis
166 *  y: Acceleration minus Gy on the y-axis
167 *  z: Acceleration minus Gz on the z-axis
168 *
169 *  Examples:
170 *    When the device lies flat on a table and is pushed on its left side
171 *    toward the right, the x acceleration value is positive.
172 *
173 *    When the device lies flat on a table, the acceleration value is +9.81,
174 *    which correspond to the acceleration of the device (0 m/s^2) minus the
175 *    force of gravity (-9.81 m/s^2).
176 *
177 *    When the device lies flat on a table and is pushed toward the sky, the
178 *    acceleration value is greater than +9.81, which correspond to the
179 *    acceleration of the device (+A m/s^2) minus the force of
180 *    gravity (-9.81 m/s^2).
181 *
182 *
183 * Magnetic Field
184 * --------------
185 *
186 *  All values are in micro-Tesla (uT) and measure the ambient magnetic
187 *  field in the X, Y and Z axis.
188 *
189 *  Magnetic Field sensors return sensor events for all 3 axes at a constant
190 *  rate defined by setDelay().
191 *
192 * Gyroscope
193 * ---------
194 *  All values are in radians/second and measure the rate of rotation
195 *  around the X, Y and Z axis.  The coordinate system is the same as is
196 *  used for the acceleration sensor. Rotation is positive in the
197 *  counter-clockwise direction (right-hand rule). That is, an observer
198 *  looking from some positive location on the x, y or z axis at a device
199 *  positioned on the origin would report positive rotation if the device
200 *  appeared to be rotating counter clockwise. Note that this is the
201 *  standard mathematical definition of positive rotation and does not agree
202 *  with the definition of roll given earlier.
203 *  The range should at least be 17.45 rad/s (ie: ~1000 deg/s).
204 *
205 * Proximity
206 * ---------
207 *
208 * The distance value is measured in centimeters.  Note that some proximity
209 * sensors only support a binary "close" or "far" measurement.  In this case,
210 * the sensor should report its maxRange value in the "far" state and a value
211 * less than maxRange in the "near" state.
212 *
213 * Proximity sensors report a value only when it changes and each time the
214 * sensor is enabled. setDelay() is ignored.
215 *
216 * Light
217 * -----
218 *
219 * The light sensor value is returned in SI lux units.
220 *
221 * Light sensors report a value only when it changes and each time the
222 * sensor is enabled. setDelay() is ignored.
223 *
224 * Pressure
225 * --------
226 *
227 * The pressure sensor value is returned in hectopascal (hPa)
228 *
229 * Pressure sensors report events at a constant rate defined by setDelay().
230 *
231 * Gravity
232 * -------
233 * A gravity output indicates the direction of and magnitude of gravity in the devices's
234 * coordinates.  On Earth, the magnitude is 9.8.  Units are m/s^2.  The coordinate system
235 * is the same as is used for the acceleration sensor.
236 *
237 * Linear Acceleration
238 * -------------------
239 * Indicates the linear acceleration of the device in device coordinates, not including gravity.
240 * This output is essentially Acceleration - Gravity.  Units are m/s^2.  The coordinate system is
241 * the same as is used for the acceleration sensor.
242 *
243 * Rotation Vector
244 * ---------------
245 * A rotation vector represents the orientation of the device as a combination
246 * of an angle and an axis, in which the device has rotated through an angle
247 * theta around an axis <x, y, z>. The three elements of the rotation vector
248 * are <x*sin(theta/2), y*sin(theta/2), z*sin(theta/2)>, such that the magnitude
249 * of the rotation vector is equal to sin(theta/2), and the direction of the
250 * rotation vector is equal to the direction of the axis of rotation. The three
251 * elements of the rotation vector are equal to the last three components of a
252 * unit quaternion <cos(theta/2), x*sin(theta/2), y*sin(theta/2), z*sin(theta/2)>.
253 * Elements of the rotation vector are unitless.  The x, y, and z axis are defined
254 * in the same was as for the acceleration sensor.
255 */
256
257typedef struct {
258    union {
259        float v[3];
260        struct {
261            float x;
262            float y;
263            float z;
264        };
265        struct {
266            float azimuth;
267            float pitch;
268            float roll;
269        };
270    };
271    int8_t status;
272    uint8_t reserved[3];
273} sensors_vec_t;
274
275/**
276 * Union of the various types of sensor data
277 * that can be returned.
278 */
279typedef struct sensors_event_t {
280    /* must be sizeof(struct sensors_event_t) */
281    int32_t version;
282
283    /* sensor identifier */
284    int32_t sensor;
285
286    /* sensor type */
287    int32_t type;
288
289    /* reserved */
290    int32_t reserved0;
291
292    /* time is in nanosecond */
293    int64_t timestamp;
294
295    union {
296        float           data[16];
297
298        /* acceleration values are in meter per second per second (m/s^2) */
299        sensors_vec_t   acceleration;
300
301        /* magnetic vector values are in micro-Tesla (uT) */
302        sensors_vec_t   magnetic;
303
304        /* orientation values are in degrees */
305        sensors_vec_t   orientation;
306
307        /* gyroscope values are in rad/s */
308        sensors_vec_t   gyro;
309
310        /* temperature is in degrees centigrade (Celsius) */
311        float           temperature;
312
313        /* distance in centimeters */
314        float           distance;
315
316        /* light in SI lux units */
317        float           light;
318
319        /* pressure in hectopascal (hPa) */
320        float           pressure;
321    };
322    uint32_t        reserved1[4];
323} sensors_event_t;
324
325
326
327struct sensor_t;
328
329/**
330 * Every hardware module must have a data structure named HAL_MODULE_INFO_SYM
331 * and the fields of this data structure must begin with hw_module_t
332 * followed by module specific information.
333 */
334struct sensors_module_t {
335    struct hw_module_t common;
336
337    /**
338     * Enumerate all available sensors. The list is returned in "list".
339     * @return number of sensors in the list
340     */
341    int (*get_sensors_list)(struct sensors_module_t* module,
342            struct sensor_t const** list);
343};
344
345struct sensor_t {
346    /* name of this sensors */
347    const char*     name;
348    /* vendor of the hardware part */
349    const char*     vendor;
350    /* version of the hardware part + driver. The value of this field is
351     * left to the implementation and doesn't have to be monotonically
352     * increasing.
353     */
354    int             version;
355    /* handle that identifies this sensors. This handle is used to activate
356     * and deactivate this sensor. The value of the handle must be 8 bits
357     * in this version of the API.
358     */
359    int             handle;
360    /* this sensor's type. */
361    int             type;
362    /* maximaum range of this sensor's value in SI units */
363    float           maxRange;
364    /* smallest difference between two values reported by this sensor */
365    float           resolution;
366    /* rough estimate of this sensor's power consumption in mA */
367    float           power;
368    /* minimum delay allowed between events in microseconds. A value of zero
369     * means that this sensor doesn't report events at a constant rate, but
370     * rather only when a new data is available */
371    int32_t         minDelay;
372    /* reserved fields, must be zero */
373    void*           reserved[8];
374};
375
376
377/**
378 * Every device data structure must begin with hw_device_t
379 * followed by module specific public methods and attributes.
380 */
381struct sensors_poll_device_t {
382    struct hw_device_t common;
383
384    /** Activate/deactivate one sensor.
385     *
386     * @param handle is the handle of the sensor to change.
387     * @param enabled set to 1 to enable, or 0 to disable the sensor.
388     *
389     * @return 0 on success, negative errno code otherwise
390     */
391    int (*activate)(struct sensors_poll_device_t *dev,
392            int handle, int enabled);
393
394    /**
395     * Set the delay between sensor events in nanoseconds for a given sensor.
396     * It is an error to set a delay inferior to the value defined by
397     * sensor_t::minDelay. If sensor_t::minDelay is zero, setDelay() is
398     * ignored and returns 0.
399     *
400     * @return 0 if successful, < 0 on error
401     */
402    int (*setDelay)(struct sensors_poll_device_t *dev,
403            int handle, int64_t ns);
404
405    /**
406     * Returns an array of sensor data.
407     * This function must block until events are available.
408     *
409     * @return the number of events read on success, or -errno in case of an error.
410     * This function should never return 0 (no event).
411     *
412     */
413    int (*poll)(struct sensors_poll_device_t *dev,
414            sensors_event_t* data, int count);
415};
416
417/** convenience API for opening and closing a device */
418
419static inline int sensors_open(const struct hw_module_t* module,
420        struct sensors_poll_device_t** device) {
421    return module->methods->open(module,
422            SENSORS_HARDWARE_POLL, (struct hw_device_t**)device);
423}
424
425static inline int sensors_close(struct sensors_poll_device_t* device) {
426    return device->common.close(&device->common);
427}
428
429__END_DECLS
430
431#include <hardware/sensors_deprecated.h>
432
433#endif  // ANDROID_SENSORS_INTERFACE_H
434