通过 NativeActivity NDK 访问(更快的轮询)加速度计 [英] access (faster polling) accelerometer via NativeActivity NDK
问题描述
我已经搜索了有关使用 NDK 更快地轮询加速度计的教程/答案，但还没有找到求解器.刚刚在 此处 找到了 androiddevelopers 文档.
I've searched for a tutorial/an answer on polling accelerometer faster with NDK but didnt find solver yet. just found an androiddevelopers documentation here.
我需要的是每秒大约 100 个样本 (100Hz) 的轮询加速，默认情况下，我的设备(带有姜饼 2.3.5 的三星 Galaxy SL i9003)和默认 SENSOR_DELAY_FASTEST 只能每秒获得大约 60 个样本(60Hz).因此，我尝试通过使用 NDK 通过 NativeActivity 访问传感器，方法是生成我尝试基于 sensor.h 和 looper.h 创建的 .c 文件:
what i need is polling acceleration about 100 samples per second (100Hz), by default my device (Samsung Galaxy SL i9003 with gingerbread 2.3.5) with default SENSOR_DELAY_FASTEST can only get about 60 samples persecond (60Hz). Therefore i tried to access sensor via NativeActivity with NDK by generating .c files that i try to make based on sensor.h and looper.h:
#include <jni.h>
#include <string.h>
#include <android/sensor.h>
#include <android/log.h>
#include <android/looper.h>
#define TAG "accelerondk"
#define LOGI(...) __android_log_print(ANDROID_LOG_INFO, TAG, __VA_ARGS__)
#define LOGD(...) __android_log_print(ANDROID_LOG_DEBUG, TAG, __VA_ARGS__)
#define LOOPER_ID 1
#define SAMP_PER_SEC 100 //i've changed to 120, even 10, but nothing happen
void Java_azka_web_ndk_AcceleroNDKActivity_startMonitoring(JNIEnv* env, jclass clazz) {
ASensorManager* sensorManager = ASensorManager_getInstance();
ALooper* looper = ALooper_forThread();
if(looper == NULL)
looper = ALooper_prepare(ALOOPER_PREPARE_ALLOW_NON_CALLBACKS);
ASensorRef accelerometerSensor = ASensorManager_getDefaultSensor(sensorManager,ASENSOR_TYPE_ACCELEROMETER);
LOGI("accelerometerSensor: %s, vendor: %s", ASensor_getName(accelerometerSensor), ASensor_getVendor(accelerometerSensor));
ASensorEventQueue* queue = ASensorManager_createEventQueue(sensorManager, looper, LOOPER_ID, NULL, NULL);
ASensorEventQueue_enableSensor(queue, accelerometerSensor);
ASensorEventQueue_setEventRate(queue, accelerometerSensor, (1000L/SAMP_PER_SEC)*1000);
int ident;//identifier
int events;
while (1) {
while ((ident=ALooper_pollAll(-1, NULL, &events, NULL) >= 0)) {
// If a sensor has data, process it now.
if (ident == LOOPER_ID) {
ASensorEvent event;
while (ASensorEventQueue_getEvents(queue, &event, 1) > 0) {
LOGI("aaaaaaa accelerometer X = %f y = %f z=%f ", event.acceleration.x, event.acceleration.y, event.acceleration.z);
}
}
}
}
}
到目前为止，我已经能够使用 NativeActivity 访问加速度计，但是所采取的数字样本没有变化.即使我改变 ASensorEventQueue_setEventRate 足够大或足够小，加速度记录仍然大约每秒 60 个样本(每 15 毫秒 1 个样本)
so far, i've been able to access accelerometer with NativeActivity, but there is no change with number sample had taken. even when i change ASensorEventQueue_setEventRate big enough or small enough the acceleration recorded still about 60 samples per second (1 samples per 15 milisec)
我的代码有错误吗?或者我忘记的东西?
is there any mistakes in my code? or something that i forget with?
提前致谢
推荐答案
我还尝试了一些关于传感器采样率的事情.我使用的是 Galaxy Nexus.如果我只使用 Acc-Sensor，频率非常低(大约 40Hz)，但如果我使用 Acc-Sensor 加上磁传感器和陀螺传感器，每个传感器的采样率约为 100Hz.我无法解释为什么会发生这种情况.另一个观察结果是传递给 ASensorEventQueue_setEventRate 的值没有效果.采样率始终相同.SDK-Code 的行为完全相同.
I also tried a few things with the sample rate of sensors. I use a Galaxy Nexus. If I use only the Acc-Sensor the frequency is very low (about 40Hz), but if I use the Acc-Sensor plus the magnetic- and the gyro-sensor the sample rate for each sensor is about 100Hz. I have no explanation why this happens. Another observation is that the values passed to ASensorEventQueue_setEventRate have no effect. The sample-rate is always the same. The behaviour is exactly the same for SDK-Code.
这是我用于基准测试的代码:
Here is the code I used for benchmarking:
#include <string.h>
#include <jni.h>
#include <android/sensor.h>
#include <android/looper.h>
#include <android/log.h>
#include <time.h>
#define LOGI(...) ((void)__android_log_print(ANDROID_LOG_INFO, "TestJNIActivity", __VA_ARGS__))
#define LOOPER_ID 1
#define SAMP_PER_SEC 100
ASensorEventQueue* sensorEventQueue;
int accCounter = 0;
int64_t lastAccTime = 0;
int gyroCounter = 0;
int64_t lastGyroTime = 0;
int magCounter = 0;
int64_t lastMagTime = 0;
/* This is a trivial JNI example where we use a native method
* to return a new VM String. See the corresponding Java source
* file located at:
*
* apps/samples/hello-jni/project/src/com/example/HelloJni/HelloJni.java
*/
static int get_sensor_events(int fd, int events, void* data);
struct tm* start;
struct tm* finish;
jstring
Java_de_tum_ndktest_TestJNIActivity_stringFromJNI( JNIEnv* env, jobject thiz )
{
LOGI("stringFromJNI");
return (*env)->NewStringUTF(env,"Hello from JNI !");
}
void
Java_de_tum_ndktest_TestJNIActivity_sensorValue( JNIEnv* env, jobject thiz ) {
ASensorEvent event;
int events, ident;
ASensorManager* sensorManager;
const ASensor* accSensor;
const ASensor* gyroSensor;
const ASensor* magSensor;
void* sensor_data = malloc(1000);
LOGI("sensorValue() - ALooper_forThread()");
ALooper* looper = ALooper_forThread();
if(looper == NULL)
{
looper = ALooper_prepare(ALOOPER_PREPARE_ALLOW_NON_CALLBACKS);
}
sensorManager = ASensorManager_getInstance();
accSensor = ASensorManager_getDefaultSensor(sensorManager, ASENSOR_TYPE_ACCELEROMETER);
gyroSensor = ASensorManager_getDefaultSensor(sensorManager, ASENSOR_TYPE_GYROSCOPE);
magSensor = ASensorManager_getDefaultSensor(sensorManager, ASENSOR_TYPE_MAGNETIC_FIELD);
sensorEventQueue = ASensorManager_createEventQueue(sensorManager, looper, 3, get_sensor_events, sensor_data);
ASensorEventQueue_enableSensor(sensorEventQueue, accSensor);
ASensorEventQueue_enableSensor(sensorEventQueue, gyroSensor);
ASensorEventQueue_enableSensor(sensorEventQueue, magSensor);
//Sampling rate: 100Hz
int a = ASensor_getMinDelay(accSensor);
int b = ASensor_getMinDelay(gyroSensor);
int c = ASensor_getMinDelay(magSensor);
LOGI("min-delay: %d, %d, %d",a,b,c);
ASensorEventQueue_setEventRate(sensorEventQueue, accSensor, 100000);
ASensorEventQueue_setEventRate(sensorEventQueue, gyroSensor, 100000);
ASensorEventQueue_setEventRate(sensorEventQueue, magSensor, 100000);
LOGI("sensorValue() - START");
}
static int get_sensor_events(int fd, int events, void* data) {
ASensorEvent event;
//ASensorEventQueue* sensorEventQueue;
while (ASensorEventQueue_getEvents(sensorEventQueue, &event, 1) > 0) {
if(event.type == ASENSOR_TYPE_ACCELEROMETER) {
//LOGI("accl(x,y,z,t): %f %f %f %lld", event.acceleration.x, event.acceleration.y, event.acceleration.z, event.timestamp);
if(accCounter == 0 || accCounter == 1000)
{
LOGI("Acc-Time: %lld (%f)", event.timestamp,((double)(event.timestamp-lastAccTime))/1000000000.0);
lastAccTime = event.timestamp;
accCounter = 0;
}
accCounter++;
}
else if(event.type == ASENSOR_TYPE_GYROSCOPE) {
//LOGI("accl(x,y,z,t): %f %f %f %lld", event.acceleration.x, event.acceleration.y, event.acceleration.z, event.timestamp);
if(gyroCounter == 0 || gyroCounter == 1000)
{
LOGI("Gyro-Time: %lld (%f)", event.timestamp,((double)(event.timestamp-lastGyroTime))/1000000000.0);
lastGyroTime = event.timestamp;
gyroCounter = 0;
}
gyroCounter++;
}
else if(event.type == ASENSOR_TYPE_MAGNETIC_FIELD) {
//LOGI("accl(x,y,z,t): %f %f %f %lld", event.acceleration.x, event.acceleration.y, event.acceleration.z, event.timestamp);
if(magCounter == 0 || magCounter == 1000)
{
LOGI("Mag-Time: %lld (%f)", event.timestamp,((double)(event.timestamp-lastMagTime))/1000000000.0);
lastMagTime = event.timestamp;
magCounter = 0;
}
magCounter++;
}
}
//should return 1 to continue receiving callbacks, or 0 to unregister
return 1;
}
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