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/*
* Copyright (C) 2010 The Android Open Source Project
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
#include <stdint.h>
#include <math.h>
#include <sys/types.h>
#include <utils/Errors.h>
#include <hardware/sensors.h>
#include "GravitySensor.h"
#include "SensorDevice.h"
#include "SensorFusion.h"
namespace android {
// ---------------------------------------------------------------------------
GravitySensor::GravitySensor(sensor_t const* list, size_t count)
: mSensorDevice(SensorDevice::getInstance()),
mSensorFusion(SensorFusion::getInstance()),
mAccTime(0),
mLowPass(M_SQRT1_2, 1.5f),
mX(mLowPass), mY(mLowPass), mZ(mLowPass)
{
for (size_t i=0 ; i<count ; i++) {
if (list[i].type == SENSOR_TYPE_ACCELEROMETER) {
mAccelerometer = Sensor(list + i);
break;
}
}
}
bool GravitySensor::process(sensors_event_t* outEvent,
const sensors_event_t& event)
{
const static double NS2S = 1.0 / 1000000000.0;
if (event.type == SENSOR_TYPE_ACCELEROMETER) {
vec3_t g;
if (mSensorFusion.hasGyro()) {
if (!mSensorFusion.hasEstimate())
return false;
const mat33_t R(mSensorFusion.getRotationMatrix());
// FIXME: we need to estimate the length of gravity because
// the accelerometer may have a small scaling error. This
// translates to an offset in the linear-acceleration sensor.
g = R[2] * GRAVITY_EARTH;
} else {
const double now = event.timestamp * NS2S;
if (mAccTime == 0) {
g.x = mX.init(event.acceleration.x);
g.y = mY.init(event.acceleration.y);
g.z = mZ.init(event.acceleration.z);
} else {
double dT = now - mAccTime;
mLowPass.setSamplingPeriod(dT);
g.x = mX(event.acceleration.x);
g.y = mY(event.acceleration.y);
g.z = mZ(event.acceleration.z);
}
g *= (GRAVITY_EARTH / length(g));
mAccTime = now;
}
*outEvent = event;
outEvent->data[0] = g.x;
outEvent->data[1] = g.y;
outEvent->data[2] = g.z;
outEvent->sensor = '_grv';
outEvent->type = SENSOR_TYPE_GRAVITY;
return true;
}
return false;
}
status_t GravitySensor::activate(void* ident, bool enabled) {
status_t err;
if (mSensorFusion.hasGyro()) {
err = mSensorFusion.activate(this, enabled);
} else {
err = mSensorDevice.activate(this, mAccelerometer.getHandle(), enabled);
if (err == NO_ERROR) {
if (enabled) {
mAccTime = 0;
}
}
}
return err;
}
status_t GravitySensor::setDelay(void* ident, int handle, int64_t ns)
{
if (mSensorFusion.hasGyro()) {
return mSensorFusion.setDelay(this, ns);
} else {
return mSensorDevice.setDelay(this, mAccelerometer.getHandle(), ns);
}
}
Sensor GravitySensor::getSensor() const {
sensor_t hwSensor;
hwSensor.name = "Gravity Sensor";
hwSensor.vendor = "Google Inc.";
hwSensor.version = mSensorFusion.hasGyro() ? 3 : 2;
hwSensor.handle = '_grv';
hwSensor.type = SENSOR_TYPE_GRAVITY;
hwSensor.maxRange = GRAVITY_EARTH * 2;
hwSensor.resolution = mAccelerometer.getResolution();
hwSensor.power = mSensorFusion.hasGyro() ?
mSensorFusion.getPowerUsage() : mAccelerometer.getPowerUsage();
hwSensor.minDelay = mSensorFusion.hasGyro() ?
mSensorFusion.getMinDelay() : mAccelerometer.getMinDelay();
Sensor sensor(&hwSensor);
return sensor;
}
// ---------------------------------------------------------------------------
}; // namespace android
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