Android Things UserSensor.Builder -无法创建距离传感器驱动程序

Question

我正试图为标准的HC-SR04超声波传感器创建一个Android设备驱动程序。我相信我的事件序列是正确的：见页脚，但无法将其注册为UserSensor。

userSensor = UserSensor.Builder()
    .setName("HC-SR04 Ultrasonic Distance Sensor")
    .setVersion(1)
    // If boolean "on face or not," should I use something linear like TYPE_LIGHT
    .setType(Sensor.TYPE_PROXIMITY) 
    .setDriver(this) // UserSensorDriver  
    .build()

此时，将UserSensor注册到UserDriverManager (完成)和向SensorManager注册它有什么区别呢？有什么能阻止它出现在传感器列表中的吗？我需要等到传感器像sensorManager.registerDynamicSensorCallback那样“准备好”吗？

val sensorManager = context.getSystemService(Context.SENSOR_SERVICE) as SensorManager
sensorManager.registerListener(this, // SensorEventListener.onSensorChanged
    sensorManager.getDefaultSensor(Sensor.TYPE_PROXIMITY),
    SensorManager.SENSOR_DELAY_NORMAL)

无论我如何尝试，我都会得到"E/SensorManager:传感器或侦听器为空“的(这在Kotlin中更令人惊讶，因为空值不应该像它那样偷偷溜进来)。

我的传感器/也是要点

/** Callback for when the distance changes "enough to care" */
interface SignificantDistanceChangeListener {
    fun onDistanceChanged(distanceCm: Float)
}

/**
 * User Sensor - Ultrasonic range finder
 */
class HCSR04(context: Context, val sdcl: SignificantDistanceChangeListener) : UserSensorDriver(), SensorEventListener, AutoCloseable {
    private val LOG = Logger.getLogger(this.javaClass.name)
    private val gpio = PeripheralManagerService().openGpio("BCM23")
    private val distanceReading: BlockingQueue<Float> = ArrayBlockingQueue(1)
    // Choreography of each ping
    private val scheduler: ScheduledExecutorService = Executors.newScheduledThreadPool(1)
    private val userSensor: UserSensor

    init {
        userSensor = UserSensor.Builder()
                .setName("HC-SR04 Ultrasonic Distance Sensor")
                .setVersion(1)
                .setType(Sensor.TYPE_PROXIMITY) // Could this be something more linear like TYPE_LIGHT
                .setDriver(this)
                .build()
        UserDriverManager.getManager().registerSensor(userSensor)

        val sensorManager = context.getSystemService(Context.SENSOR_SERVICE) as SensorManager
        LOG.info("ALL Sensors: ${sensorManager.getSensorList(Sensor.TYPE_ALL)}")

        sensorManager.registerDynamicSensorCallback(object : SensorManager.DynamicSensorCallback() {
            override fun onDynamicSensorConnected(sensor: Sensor) {
                LOG.info("onDynamicSensorConnected")
                if (sensor.type == Sensor.TYPE_PROXIMITY) {
                    sensorManager.registerListener(
                            this@HCSR04,
                            sensor,
                            SensorManager.SENSOR_DELAY_NORMAL
                    )
                }
            }
        })

    }

    val gpioEdgeCallback = object : GpioCallback() {
        // Track the reply rise/fall
        private val startMs = AtomicLong()
        private val startValid = AtomicBoolean(false)

        private fun calculate() {
            val elapsed = (System.nanoTime() / 1000) - startMs.get()
            if (startValid.get() && elapsed > 0) {
                distanceReading.put(elapsed * 34000 / 2f)
            } else {
                LOG.warning("Discarding edge callback ${startMs.get()} ${startValid.get()} $elapsed")
            }
            startValid.set(false)
        }

        override fun onGpioEdge(gpio: Gpio?): Boolean {
            if (gpio != null) {
                if (gpio.value) {
                    startMs.set(System.nanoTime() / 1000)
                    startValid.set(true)
                } else {
                    calculate()
                }
                LOG.finer("GPIO input edge: ${System.nanoTime() / 1000} ${gpio.value}")
            }
            return true
        }

        override fun onGpioError(gpio: Gpio?, error: Int) = LOG.severe("$gpio Error event $error")
    }

    /** Launch a new thread to get the distance, then block until we have a result */
    override fun read(): UserSensorReading {
        distanceReading.clear()

        gpio.setDirection(Gpio.DIRECTION_OUT_INITIALLY_LOW)
        gpio.setActiveType(Gpio.ACTIVE_HIGH)
        gpio.value = false

        scheduler.schedule({ gpio.value = true }, 1, TimeUnit.MICROSECONDS)
        scheduler.schedule({ gpio.value = false }, 11, TimeUnit.MICROSECONDS)
        scheduler.schedule({
            gpio.setDirection(Gpio.DIRECTION_IN)
            gpio.setActiveType(Gpio.ACTIVE_HIGH) // redundant?
            gpio.setEdgeTriggerType(Gpio.EDGE_BOTH)
            gpio.registerGpioCallback(gpioEdgeCallback)
        }, 12, TimeUnit.MICROSECONDS)

        val distanceCm = distanceReading.take()
        gpio.unregisterGpioCallback(gpioEdgeCallback)
        LOG.info("New distance reading: $distanceCm")
        return UserSensorReading(floatArrayOf(distanceCm))
    }

    /** from @SensorEventListener */
    override fun onAccuracyChanged(sensor: Sensor, accuracy: Int) = LOG.info("$sensor accuracy change: $accuracy")

    /**
     * from @SensorEventListener
     */
    override fun onSensorChanged(event: SensorEvent) = sdcl.onDistanceChanged(event.values[0])

    /** from @AutoCloseable */
    override fun close() {
        LOG.warning("Closing Sensor HCSR04")
        UserDriverManager.getManager().unregisterSensor(userSensor)
        gpio.close()
        scheduler.shutdownNow()
    }
}

Answer 1

您可能考虑的一件事是更改传感器类型。TYPE_PROXIMITY是一个正在变化的传感器，它在当前预览中得到支持.然而，它也是一个唤醒传感器，可能还不完全支持。您可以尝试修改传感器定义以使用自定义类型：

userSensor = UserSensor.Builder()
        .setName("HC-SR04 Ultrasonic Distance Sensor")
        .setVersion(1)
        .setCustomType(Sensor.TYPE_DEVICE_PRIVATE_BASE,
                "com.example.ultrasonic",
                Sensor.REPORTING_MODE_CONTINUOUS)
        .setDriver(this)
        .build()

此时，将UserSensor注册到UserDriverManager (完成)和向SensorManager注册它有什么区别呢？

您不能直接向UserSensor注册SensorManager。Android SensorManager API的存在是为了使客户端应用程序能够从内置在设备中的传感器读取数据。UserDriverManager API的存在是为了使Android 开发人员能够向系统中添加新的传感器，您可能希望在代码的其他地方使用相同的SensorManager API来阅读这些传感器。

换句话说，您可以构建一个UserSensor，通过UserDriverManager将自定义传感器数据注入到框架中。您可以使用SensorManager提取提供给框架的数据，并在客户端应用程序中使用。

有什么能阻止它出现在传感器列表中的吗？

在传感器回调触发器之后，您应该能够使用SensorManager.getDynamicSensorList() (与getSensorList()方法不同)测试这一点。

我需要等到传感器像sensorManager.registerDynamicSensorCallback那样“准备好”吗？

动态回调将告诉您新驱动程序何时已在框架中成功注册。在调用onDynamicSensorConnected()之前，您将无法附加侦听器或查询传感器本身。