[参考译文] CC2340R5：属性表的句柄

您好！

要了解特征、您需要一些 API。 我不确定项目的作用、但代码非常可转让。 首先、您需要启动服务发现。 有多种 API 可实现这一点：

GATT_DiscAllPrimaryServices ()

GATT_DiscPrimaryServiceByUUID ()

您需要在上面找到服务句柄范围、以捕获您正在寻找的特征的句柄范围。 尽管以下示例适用于外设角色、但您可以将此代码移至器件所处的任何角色：app_peripheral.c

void Peripheral_GAPConnEventHandler(uint32 event, BLEAppUtil_msgHdr_t *pMsgData)
{
    gapEstLinkReqEvent_t *gapMsg = ( gapEstLinkReqEvent_t * )pMsgData;
    switch(event)
    {
        case BLEAPPUTIL_LINK_ESTABLISHED_EVENT:
        {

            /* Check if we reach the maximum allowed number of connections */
            if(linkDB_NumActive() < linkDB_NumConns())
            {
                /* Start advertising since there is room for more connections */
                BLEAppUtil_advStart(peripheralAdvHandle_1, &advSetStartParamsSet_1);
            }
            else
            {
                /* Stop advertising since there is no room for more connections */
                BLEAppUtil_advStop(peripheralAdvHandle_1);
            }

            // Device Info service. Note: The UUID is in little endian. Thus we are searching for the service of 0x180A
            uint8 pUUID[] = {0x0A, 0x18};
            // This is the call to discover a primary service by UUID.
            bStatus_t status = GATT_DiscPrimaryServiceByUUID(gapMsg->connectionHandle, &pUUID, ATT_BT_UUID_SIZE, BLEAppUtil_getSelfEntity());
            if (status != SUCCESS)
            {
                MenuModule_printf(APP_MENU_NUM_CONNS, 0, "DiscPrimaryServiceByUUID Failed: %d", status);
            }
            else
            {
                MenuModule_printf(APP_MENU_NUM_CONNS, 0, "DiscPrimaryServiceByUUID Success.");
            }
            break;
        }

        case BLEAPPUTIL_LINK_TERMINATED_EVENT:
        {
            BLEAppUtil_advStart(peripheralAdvHandle_1, &advSetStartParamsSet_1);
            break;
        }

        default:
        {
            break;
        }
    }
}

请确保阅读您计划用于发现该服务的 API 的所有 API 信息。 根据所使用的内容、它们会预期不同的事件、而且过程也不同。 对于这段代码、我们将使用 GATT_DiscPrimaryServiceByUUID ()、 因此我们需要处理 ATTT_FIND_BYE_TYPE_VALUE_RSP、并且我们将收到 attFindByTypeValueRsp_t 结构。

在 app_data.c 中、我们需要添加一些事件和一些修改。  

1.我们需要在数据处理程序中添加适当的事件:

/* Note that the events are of BLEAPPUTIL, but in the handler we drop the BLEAPPUTIL prefix. */
BLEAppUtil_EventHandler_t dataGATTHandler =
{
    .handlerType    = BLEAPPUTIL_GATT_TYPE,
    .pEventHandler  = GATT_EventHandler,
    .eventMask      = BLEAPPUTIL_ATT_FLOW_CTRL_VIOLATED_EVENT |
                      BLEAPPUTIL_ATT_MTU_UPDATED_EVENT |
                      BLEAPPUTIL_ATT_FIND_BY_TYPE_VALUE_RSP |
                      BLEAPPUTIL_ATT_READ_BY_TYPE_RSP
};

ATT_FIND_BY_TYPE_VALUE_RSP 是因为我们使用 GATT_DiscPrimaryServicesByUUID 查找服务的句柄。

ATT_READ_BY_TYPE_RSP 用于服务内的属性句柄、我们通过调用 GATT_DiscAllChars()来触发此事件。

我们需要添加这些事件、并将处理这些事件的方法添加到我们的数据处理程序中：

static void GATT_EventHandler(uint32 event, BLEAppUtil_msgHdr_t *pMsgData)
{
  gattMsgEvent_t *gattMsg = ( gattMsgEvent_t * )pMsgData;
  switch ( gattMsg->method )
  {
    case ATT_FLOW_CTRL_VIOLATED_EVENT:
      {
          MenuModule_printf(APP_MENU_PROFILE_STATUS_LINE, 0, "GATT status: ATT flow control is violated");
      }
      break;

    case ATT_MTU_UPDATED_EVENT:
      {
          MenuModule_printf(APP_MENU_PROFILE_STATUS_LINE, 0, "GATT status: ATT MTU update to %d",
                            gattMsg->msg.mtuEvt.MTU);
      }
      break;
    case ATT_READ_BY_TYPE_RSP:
    {
        display_index += 1;
        attReadByTypeRsp_t *response = (attReadByTypeRsp_t *)&(gattMsg->msg.readByTypeRsp);
        MenuModule_printf(display_index, 0, "GATT status: Read by type %d", response->numPairs);

        for (int i = 0; i < response->numPairs; i++)
        {
            uint16_t attributeHandle = BUILD_UINT16(response->pDataList[i * response->len + 0],
                                                    response->pDataList[i * response->len + 1]);

            uint16_t endHandle = BUILD_UINT16(response->pDataList[i * response->len + 2],
                                              response->pDataList[i * response->len + 3]);

            display_index += 1;
            MenuModule_printf(display_index, 0, "GATT status: Read by type: Handle: %x | %x", attributeHandle, endHandle);
        }
        break;

    }
    case ATT_FIND_BY_TYPE_VALUE_RSP:
    {
        display_index += 1;
        attFindByTypeValueRsp_t *response = (attFindByTypeValueRsp_t *)&(gattMsg->msg.findByTypeValueRsp);
        MenuModule_printf(display_index, 0, "GATT status: Find by type: numInfo %d", response->numInfo);

        for (int i = 0; i < response->numInfo; i++)
        {
            uint16_t attributeHandle = BUILD_UINT16(response->pHandlesInfo[i * response->numInfo + 0],
                                                    response->pHandlesInfo[i * response->numInfo + 1]);

            uint16_t endHandle = BUILD_UINT16(response->pHandlesInfo[i * response->numInfo + 2],
                                              response->pHandlesInfo[i * response->numInfo + 3]);

            display_index += 1;
            MenuModule_printf(display_index, 0, "GATT Handle start: %x | end: %x", attributeHandle, endHandle);


            /*
             * Note: The call to GATT_DiscAllChars will fail if called without a delay. Here is what TI recommends:
             *      1. Store the handles, and trigger a timer which will then call GATT_DiscAllChars with the data.
             *      2. Add a delay.
             *
             *  The reason a delay or timer is needed is because the BLE stack is still processing information. Thus leading
             *  the call to GATT_DiscAllChars to return with 'bleNotReady'. For the sake of convenience the delay implementation
             *  is provided here. However, a timer that triggers an interrupt would be a more elegant solution.
             *
             */
            ClockP_sleep(1);

            bStatus_t status = GATT_DiscAllChars(gattMsg->connHandle, attributeHandle, endHandle, BLEAppUtil_getSelfEntity());

             if (status != SUCCESS)
             {
                 display_index += 1;
                 MenuModule_printf(display_index, 0, "GATT_DiscAllChars Failed: %x", status);
             }
        }

        break;
    }

    default:
      break;
  }
}

这应该可以帮助您发现特定服务的所有特征。

这些句柄的构建方式基于 BLE 规范对它们的定义。 但是、我建议阅读代码和规范、以了解我们是如何构建属性句柄的。

上面的代码应该是使特征发现正常运行的良好开始。 我还建议阅读我们的 GATT API、以了解更多信息：

TI BLE5-Stack API 文档：ATT/GATT 

此外、阅读蓝牙核心规范将可以详细了解特征发现所需的确切过程。

希望这对您有所帮助！

此致！

Nima Behmanesh