BLE加速度计

Question

我想通过BLE发送加速度计数值到使用北欧nRF52的iOS应用程序。这个应用程序可以很好地处理标准的BLE服务(HeartRate测量、温度计等)，但当我尝试定义一个自定义的BLE加速度计服务时就不行了。在定义UUID和其他东西时，有什么特别需要我做的吗？任何帮助都将不胜感激，谢谢。

下面是我的自定义加速度计类，以及下面上传到nRF52的main.cpp。

#ifndef __BLE_ACCELEROMETER_SERVICE__
#define __BLE_ACCELEROMETER_SERVICE__

#include "ble/BLE.h"

#define UUID_ACCELEROMETER_SERVICE  "00000000-0000-1000-7450-BE2E44B06B00"

#define UUID_X_CHARACTERISTIC       "00000000-0000-1000-7450-BE2E44B06B01"
#define UUID_Y_CHARACTERISTIC       "00000000-0000-1000-7450-BE2E44B06B02"
#define UUID_Z_CHARACTERISTIC       "00000000-0000-1000-7450-BE2E44B06B03"

/**
 * @class AccelerometerService
 * @brief BLE Custom Accelerometer Service. This provides the x, y and z values of the SEEED 101020051 Grove accelerometer connected to the Nordic nRF52 DK.
 */

class AccelerometerService
{
public:

    /**
     *  @brief Add the Accelerometer Service to an existing BLE object, initialize with values for x, y and z readings, represented as doubles.
     *  @param _ble Reference to the BLE device
     *  @param _x   Initial value for the x axis
     *  @param _y   Initial value for the y axis
     *  @param _z   Initial value for the z axis
     */
    AccelerometerService(BLE &_ble, double _x = 0, double _y = 0, double _z = 0) :
    ble(_ble),
    x(_x),
    y(_y),
    z(_z),
    xAngleCharacteristic(UUID_X_CHARACTERISTIC, &x, GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_NOTIFY),
    yAngleCharacteristic(UUID_Y_CHARACTERISTIC, &y, GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_NOTIFY),
    zAngleCharacteristic(UUID_Z_CHARACTERISTIC, &z, GattCharacteristic::BLE_GATT_CHAR_PROPERTIES_NOTIFY) {

        GattCharacteristic  *readings[] = {&xAngleCharacteristic, &yAngleCharacteristic, &zAngleCharacteristic, };
        GattService         accelerometerService(UUID_ACCELEROMETER_SERVICE, readings, sizeof(readings) / sizeof(GattCharacteristic *));

        ble.addService(accelerometerService);
    }

    /**
     * @brief Update the x axis rotation with a new value.
     * @param _x - New x value from accelerometer
     */
    void update_x(uint8_t _x) {
        x = _x;
        ble.gattServer().write(xAngleCharacteristic.getValueHandle(), &x, 1);
    }

    /**
     * @brief Update the y axis rotation with a new value.
     * @param _z - New y value from accelerometer
     */
    void update_y(uint8_t _y) {
        y = _y;
        ble.gattServer().write(yAngleCharacteristic.getValueHandle(), &y, 1);
    }

    /**
     * @brief Update the z axis rotation with a new value.
     * @param _z - New z value from accelerometer
     */
    void update_z(uint8_t _z) {
        z = _z;
        ble.gattServer().write(zAngleCharacteristic.getValueHandle(), &z, 1);
    }


protected:

    /**
     * A reference to the underlying BLE instance that this object is attached to.
     * The services and characteristics will be registered in this BLE instance.
     */
    BLE &ble;

    /**
     * The current x axis rotation, represented as a double
     */
    uint8_t x;
    /**
     * The current y axis rotation, represented as a double
     */
    uint8_t y;
    /**
     * The current z axis rotation, represented as a double
     */
    uint8_t z;

    /**
     * A ReadOnlyGattCharacteristic that allows access to the peer device to the
     * x axis rotation value through BLE.
     */
    ReadOnlyGattCharacteristic<uint8_t>   xAngleCharacteristic;
    /**
     * A ReadOnlyGattCharacteristic that allows access to the peer device to the
     * y axis rotation value through BLE.
     */
    ReadOnlyGattCharacteristic<uint8_t>   yAngleCharacteristic;
    /**
     * A ReadOnlyGattCharacteristic that allows access to the peer device to the
     * z axis rotation value through BLE.
     */
    ReadOnlyGattCharacteristic<uint8_t>   zAngleCharacteristic;
};


#endif /* __BLE_ACCELEROMETER_SERVICE__ */

下面是我通过mbed.org使用的main.cpp文件。

#include "mbed.h"
#include "ble/BLE.h"
#include "AccelerometerService.h"

DigitalOut led1(LED1);
DigitalOut led2(LED2);

static AccelerometerService *accelerometerServicePtr;

// Function declarations
void bleInitComplete(BLE::InitializationCompleteCallbackContext *);
void disconnectionCallback(const Gap::DisconnectionCallbackParams_t *);

// Set device name and inital setup options
static const char       DEVICE_NAME[]        = "nRF52";
static const uint16_t   uuid16_list[]        = {0xFFFF};
static volatile bool    triggerSensorPolling = false;

static float           x = 10.0;    // Dummy values for accelerometer for now
static float           y = 15.0;
static float           z = 18.0;

/*
 *  Initialization callback
 */
void bleInitComplete(BLE::InitializationCompleteCallbackContext *params)
{
    BLE &ble = params->ble;
    ble_error_t error = params->error;

    if (error != BLE_ERROR_NONE){
        printf("*** Error occured ***\n");
        return;
    }

    /* Ensure that it is the default instance of BLE */
    if(ble.getInstanceID() != BLE::DEFAULT_INSTANCE) {
        return;
    }

    ble.gap().onDisconnection(disconnectionCallback);

    // Setup primary service
    accelerometerServicePtr = new AccelerometerService(ble, x, y, z);

    // Setup advertising
    ble.gap().setAdvertisingType(GapAdvertisingParams::ADV_CONNECTABLE_UNDIRECTED);

    // Advertising payload has a maximum of 31 bytes
    // BLE only, no classic BT
    ble.gap().accumulateAdvertisingPayload(GapAdvertisingData::BREDR_NOT_SUPPORTED |
                                           GapAdvertisingData::LE_GENERAL_DISCOVERABLE);
    // Add name
    ble.gap().accumulateAdvertisingPayload(GapAdvertisingData::COMPLETE_LOCAL_NAME, (uint8_t *)DEVICE_NAME, sizeof(DEVICE_NAME));
    // UUIDs broadcast in advertising packet
    ble.gap().accumulateAdvertisingPayload(GapAdvertisingData::COMPLETE_LIST_128BIT_SERVICE_IDS, (uint8_t *)uuid16_list, sizeof(uuid16_list));
    // Set advertising interval
    ble.gap().setAdvertisingInterval(100); //100ms

    // Start advertising
    ble.gap().startAdvertising();
}

/**
 * Restart advertising on disconnection
 */
void disconnectionCallback(const Gap::DisconnectionCallbackParams_t *)
{
    BLE::Instance(BLE::DEFAULT_INSTANCE).gap().startAdvertising();
}

/**
 * This function is called when the ble initialization process has failed
 */
void onBleInitError(BLE &ble, ble_error_t error)
{
    /* Avoid compiler warnings */
    (void) ble;
    (void) error;
    /* Initialization error handling should go here */
}

int main()
{
    // Initialize program
    printf("\n\r *** Starting Main Loop *** \r\n");

    BLE &ble = BLE::Instance(BLE::DEFAULT_INSTANCE);
    ble.init(bleInitComplete);

    while (ble.hasInitialized() == false)
    {
        while (true)
        {
            if (triggerSensorPolling && ble.gap().getState().connected) {
                triggerSensorPolling = false;

                accelerometerServicePtr->update_x(x);
                accelerometerServicePtr->update_y(y);
                accelerometerServicePtr->update_z(z);
            } 
            else {
                ble.waitForEvent();   // Infinite loop waiting for BLE interrupt events
            }
        }
    }
}

Answer 1

这是错误的，您正在发送一个不好的广告数据包。(0xFFFF ==在此处插入16位服务)

...
uuid16_list[]        = {0xFFFF};
...
...
COMPLETE_LIST_128BIT_SERVICE_IDS, (uint8_t *)uuid16_list, sizeof(uuid16_list)

蓝牙有保留的16位标识符，它们使用保留的UUID空间。

查看此页面：What range of Bluetooth UUIDs can be used for vendor defined profiles?

您需要做的是在128位列表中指定完整的UUID。

我无法编译这段代码，但可以尝试下面这样的代码

char 128bitlist[] = {,0x00,0x00,0x00,0x00 ,0x00,0x00 ,0x10,0x00 ,0x74,0x50 ,0xBE,0x2E,0x44,0xB0,0x6B,0x00};
...
...
ble.gap().accumulateAdvertisingPayload (GapAdvertisingData::COMPLETE_LIST_128BIT_SERVICE_IDS, (uint8_t *) 128bitlist, 1);

Lightblue是一个检查广告数据的优秀工具。它是免费的，而且提供了丰富的信息。你应该用这个工具检查Android和IOS上的广告。

另一件需要检查的事情是，你不要把广告包填得太满。如果您的设备名称太长，加上128位的UUID，您可能会过度填充和损坏数据包。试着去掉它的名字，或者让它变得非常简短。

Answer 2

有两件事需要考虑。

首先，为了与具有自定义服务的BLE设备进行通信，然后您需要在中央侧即例如在移动侧的匹配应用程序。因为标准应用程序将始终只查找预期的标准配置文件。

其次，为了在您的设备固件中实现自定义配置文件，北欧公司为其UART (NUS)配置文件提供了一个示例。您可以使用该示例作为参考，并根据需要进行更改，例如服务和特征的UUID。