sensors.h revision 3120b58768ff6aad5ad169b9c18f962ef6abb3c5 
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
62/**
63 * Values returned by the accelerometer in various locations in the universe.
64 * all values are in SI units (m/s^2)
65 */
66
67#define GRAVITY_SUN             (275.0f)
68#define GRAVITY_EARTH           (9.80665f)
69
70/** Maximum magnetic field on Earth's surface */
71#define MAGNETIC_FIELD_EARTH_MAX    (60.0f)
72
73/** Minimum magnetic field on Earth's surface */
74#define MAGNETIC_FIELD_EARTH_MIN    (30.0f)
75
76
77/**
78 * status of each sensor
79 */
80
81#define SENSOR_STATUS_UNRELIABLE        0
82#define SENSOR_STATUS_ACCURACY_LOW      1
83#define SENSOR_STATUS_ACCURACY_MEDIUM   2
84#define SENSOR_STATUS_ACCURACY_HIGH     3
85
86/**
87 * Definition of the axis
88 * ----------------------
89 *
90 * This API is relative to the screen of the device in its default orientation,
91 * that is, if the device can be used in portrait or landscape, this API
92 * is only relative to the NATURAL orientation of the screen. In other words,
93 * the axis are not swapped when the device's screen orientation changes.
94 * Higher level services /may/ perform this transformation.
95 *
96 *   x<0         x>0
97 *                ^
98 *                |
99 *    +-----------+-->  y>0
100 *    |           |
101 *    |           |
102 *    |           |
103 *    |           |   / z<0
104 *    |           |  /
105 *    |           | /
106 *    O-----------+/
107 *    |[]  [ ]  []/
108 *    +----------/+     y<0
109 *              /
110 *             /
111 *           |/ z>0 (toward the sky)
112 *
113 *    O: Origin (x=0,y=0,z=0)
114 *
115 *
116 * Orientation
117 * -----------
118 *
119 * All values are angles in degrees.
120 *
121 * Orientation sensors return sensor events for all 3 axes at a constant
122 * rate defined by setDelay().
123 *
124 * azimuth: angle between the magnetic north direction and the Y axis, around
125 *  the Z axis (0<=azimuth<360).
126 *      0=North, 90=East, 180=South, 270=West
127 *
128 * pitch: Rotation around X axis (-180<=pitch<=180), with positive values when
129 *  the z-axis moves toward the y-axis.
130 *
131 * roll: Rotation around Y axis (-90<=roll<=90), with positive values when
132 *  the x-axis moves towards the z-axis.
133 *
134 * Note: For historical reasons the roll angle is positive in the clockwise
135 *  direction (mathematically speaking, it should be positive in the
136 *  counter-clockwise direction):
137 *
138 *                Z
139 *                ^
140 *  (+roll)  .--> |
141 *          /     |
142 *         |      |  roll: rotation around Y axis
143 *     X <-------(.)
144 *                 Y
145 *       note that +Y == -roll
146 *
147 *
148 *
149 * Note: This definition is different from yaw, pitch and roll used in aviation
150 *  where the X axis is along the long side of the plane (tail to nose).
151 *
152 *
153 * Acceleration
154 * ------------
155 *
156 *  All values are in SI units (m/s^2) and measure the acceleration of the
157 *  device minus the force of gravity.
158 *
159 *  Acceleration sensors return sensor events for all 3 axes at a constant
160 *  rate defined by setDelay().
161 *
162 *  x: Acceleration minus Gx on the x-axis
163 *  y: Acceleration minus Gy on the y-axis
164 *  z: Acceleration minus Gz on the z-axis
165 *
166 *  Examples:
167 *    When the device lies flat on a table and is pushed on its left side
168 *    toward the right, the x acceleration value is positive.
169 *
170 *    When the device lies flat on a table, the acceleration value is +9.81,
171 *    which correspond to the acceleration of the device (0 m/s^2) minus the
172 *    force of gravity (-9.81 m/s^2).
173 *
174 *    When the device lies flat on a table and is pushed toward the sky, the
175 *    acceleration value is greater than +9.81, which correspond to the
176 *    acceleration of the device (+A m/s^2) minus the force of
177 *    gravity (-9.81 m/s^2).
178 *
179 *
180 * Magnetic Field
181 * --------------
182 *
183 *  All values are in micro-Tesla (uT) and measure the ambient magnetic
184 *  field in the X, Y and Z axis.
185 *
186 *  Magnetic Field sensors return sensor events for all 3 axes at a constant
187 *  rate defined by setDelay().
188 *
189 * Proximity
190 * ---------
191 *
192 * The distance value is measured in centimeters.  Note that some proximity
193 * sensors only support a binary "close" or "far" measurement.  In this case,
194 * the sensor should report its maxRange value in the "far" state and a value
195 * less than maxRange in the "near" state.
196 *
197 * Proximity sensors report a value only when it changes and each time the
198 * sensor is enabled. setDelay() is ignored.
199 *
200 * Light
201 * -----
202 *
203 * The light sensor value is returned in SI lux units.
204 *
205 * Light sensors report a value only when it changes and each time the
206 * sensor is enabled. setDelay() is ignored.
207 *
208 * Pressure
209 * --------
210 *
211 * The pressure sensor value is returned in hectopascal (hPa)
212 *
213 * Pressure sensors report events at a constant rate defined by setDelay().
214 *
215 * Gyro
216 * --------
217 *
218 * The gyroscope sensor values are returned in degrees per second (dps)
219 *
220 * Gyroscope sensor report events at a constant rate defined by setDelay().
221 *
222 */
223typedef struct {
224    union {
225        float v[3];
226        struct {
227            float x;
228            float y;
229            float z;
230        };
231        struct {
232            float azimuth;
233            float pitch;
234            float roll;
235        };
236    };
237    int8_t status;
238    uint8_t reserved[3];
239} sensors_vec_t;
240
241/**
242 * Union of the various types of sensor data
243 * that can be returned.
244 */
245typedef struct sensors_event_t {
246    /* must be sizeof(struct sensors_event_t) */
247    int32_t version;
248
249    /* sensor identifier */
250    int32_t sensor;
251
252    /* sensor type */
253    int32_t type;
254
255    /* reserved */
256    int32_t reserved0;
257
258    /* time is in nanosecond */
259    int64_t timestamp;
260
261    union {
262        float           data[16];
263
264        /* acceleration values are in meter per second per second (m/s^2) */
265        sensors_vec_t   acceleration;
266
267        /* magnetic vector values are in micro-Tesla (uT) */
268        sensors_vec_t   magnetic;
269
270        /* orientation values are in degrees */
271        sensors_vec_t   orientation;
272
273	/* angular velocity in degrees per second (dps) */
274	sensors_vec_t   gyro;
275
276        /* temperature is in degrees centigrade (Celsius) */
277        float           temperature;
278
279        /* distance in centimeters */
280        float           distance;
281
282        /* light in SI lux units */
283        float           light;
284
285        /* pressure in hectopascal (hPa) */
286        float           pressure;
287    };
288    uint32_t        reserved1[4];
289} sensors_event_t;
290
291
292
293struct sensor_t;
294
295/**
296 * Every hardware module must have a data structure named HAL_MODULE_INFO_SYM
297 * and the fields of this data structure must begin with hw_module_t
298 * followed by module specific information.
299 */
300struct sensors_module_t {
301    struct hw_module_t common;
302
303    /**
304     * Enumerate all available sensors. The list is returned in "list".
305     * @return number of sensors in the list
306     */
307    int (*get_sensors_list)(struct sensors_module_t* module,
308            struct sensor_t const** list);
309};
310
311struct sensor_t {
312    /* name of this sensors */
313    const char*     name;
314    /* vendor of the hardware part */
315    const char*     vendor;
316    /* version of the hardware part + driver. The value of this field is
317     * left to the implementation and doesn't have to be monotonically
318     * increasing.
319     */
320    int             version;
321    /* handle that identifies this sensors. This handle is used to activate
322     * and deactivate this sensor. The value of the handle must be 8 bits
323     * in this version of the API.
324     */
325    int             handle;
326    /* this sensor's type. */
327    int             type;
328    /* maximaum range of this sensor's value in SI units */
329    float           maxRange;
330    /* smallest difference between two values reported by this sensor */
331    float           resolution;
332    /* rough estimate of this sensor's power consumption in mA */
333    float           power;
334    /* minimum delay allowed between events in microseconds. A value of zero
335     * means that this sensor doesn't report events at a constant rate, but
336     * rather only when a new data is available */
337    int32_t         minDelay;
338    /* reserved fields, must be zero */
339    void*           reserved[8];
340};
341
342
343/**
344 * Every device data structure must begin with hw_device_t
345 * followed by module specific public methods and attributes.
346 */
347struct sensors_poll_device_t {
348    struct hw_device_t common;
349
350    /** Activate/deactivate one sensor.
351     *
352     * @param handle is the handle of the sensor to change.
353     * @param enabled set to 1 to enable, or 0 to disable the sensor.
354     *
355     * @return 0 on success, negative errno code otherwise
356     */
357    int (*activate)(struct sensors_poll_device_t *dev,
358            int handle, int enabled);
359
360    /**
361     * Set the delay between sensor events in nanoseconds for a given sensor.
362     * It is an error to set a delay inferior to the value defined by
363     * sensor_t::minDelay. If sensor_t::minDelay is zero, setDelay() is
364     * ignored and returns 0.
365     *
366     * @return 0 if successful, < 0 on error
367     */
368    int (*setDelay)(struct sensors_poll_device_t *dev,
369            int handle, int64_t ns);
370
371    /**
372     * Returns an array of sensor data.
373     * This function must block until events are available.
374     *
375     * @return the number of events read on success, or -errno in case of an error.
376     * This function should never return 0 (no event).
377     *
378     */
379    int (*poll)(struct sensors_poll_device_t *dev,
380            sensors_event_t* data, int count);
381};
382
383/** convenience API for opening and closing a device */
384
385static inline int sensors_open(const struct hw_module_t* module,
386        struct sensors_poll_device_t** device) {
387    return module->methods->open(module,
388            SENSORS_HARDWARE_POLL, (struct hw_device_t**)device);
389}
390
391static inline int sensors_close(struct sensors_poll_device_t* device) {
392    return device->common.close(&device->common);
393}
394
395__END_DECLS
396
397#include <hardware/sensors_deprecated.h>
398
399#endif  // ANDROID_SENSORS_INTERFACE_H
400