qt - Qt - 无法读取特征的描述符 - BLE
问题描述
我在使用 Bluetooth Low Energy Qt api 读取特性时遇到问题。我正在与之通信的设备是 Decawave DWM1001 模块。我正在按照文档中的教程进行操作。我设法连接到设备,成功读取并创建了它的服务。该设备具有 UUID 的“网络节点服务”:680c21d9-c946-4c1f-9c11-baa1c21329e7,我正在尝试从中读取特征。我调用 QLowEnergyController::connectToDevice() 方法,它找到了服务并为它创建了一个名为 nodeService 的 QLowEnergyService 对象。
void BluetoothConnector::serviceDiscovered(const QBluetoothUuid &newService)
{
qDebug() << "Service discovered: " << newService.toString();
if (newService == QBluetoothUuid(nodeServiceUUID)) {
nodeService = controller->createServiceObject(QBluetoothUuid(nodeServiceUUID), this);
if (nodeService) {
qDebug() << "Node service created";
connect(nodeService, &QLowEnergyService::stateChanged, this, &BluetoothConnector::serviceStateChanged);
connect(nodeService, &QLowEnergyService::characteristicChanged, this, &BluetoothConnector::updateCharacteristic);
//connect(nodeService, &QLowEnergyService::descriptorWritten, this, &BLTest::confirmedDescriptorWrite);
nodeService->discoverDetails();
} else {
qDebug() << "Node service not found.";
}
}
}
nodeService 已成功创建(我得到“Node service created”日志),然后我连接服务的信号和插槽,然后在 nodeService 上调用 discoverDetails()。serviceStateChanged() 插槽如下所示:
void BluetoothConnector::serviceStateChanged(QLowEnergyService::ServiceState newState)
{
if (newState == QLowEnergyService::DiscoveringServices) {
qDebug() << "Discovering services";
} else if (newState == QLowEnergyService::ServiceDiscovered) {
qDebug() << "Service discovered";
const QLowEnergyCharacteristic networkIdChar = nodeService->characteristic(QBluetoothUuid(networkIdUUID));
const QLowEnergyCharacteristic dataModeChar = nodeService->characteristic(QBluetoothUuid(dataModeUUID));
const QLowEnergyCharacteristic locationChar = nodeService->characteristic(QBluetoothUuid(locationUUID));
if (networkIdChar.isValid() && dataModeChar.isValid() && locationChar.isValid()) {
auto idValue = networkIdChar.value();
auto modeValue = dataModeChar.value();
auto locValue = locationChar.value();
qDebug() << "Network ID: " << idValue;
qDebug() << "Mode: " << modeValue;
qDebug() << "Location: " << locValue;
auto notificationDesc = locationChar.descriptor(QBluetoothUuid::ClientCharacteristicConfiguration);
if (notificationDesc.isValid()) {
qDebug() << "Notification desc valid";
nodeService->writeDescriptor(notificationDesc, QByteArray::fromHex("0100"));
}
} else {
qDebug() << "Characteristic invalid";
}
}
}
我得到“发现服务”日志,然后应用程序挂起一段时间,然后我得到:
"Cannot read descriptor (onDescReadFinished 3): \"{00002902-0000-1000-8000-00805f9b34fb}\" \"{3f0afd88-7770-46b0-b5e7-9fc099598964}\" \"org.freedesktop.DBus.Error.NoReply\" \"Did not receive a reply. Possible causes include: the remote application did not send a reply, the message bus security policy blocked the reply, the reply timeout expired, or the network connection was broken.\""
"LowEnergy controller disconnected"
"Aborting onCharReadFinished due to disconnect"
它无法读取 00002902-0000-1000-8000-00805f9b34fb 这是 3f0afd88-7770-46b0-b5e7-9fc099598964 特征(特定于供应商)的 CCCD 描述符。无法弄清楚出了什么问题以及为什么它无法从设备中读取特征。我是否需要做其他事情才能使其正常工作?
谢谢。
- -更新 - -
蓝牙连接器类:
#include "bluetoothconnector.h"
#include <QTimer>
BluetoothConnector::BluetoothConnector(QObject *parent) : QObject(parent)
{
configureDiscoveryAgent();
}
void BluetoothConnector::scan()
{
agent->start(QBluetoothDeviceDiscoveryAgent::LowEnergyMethod);
}
void BluetoothConnector::connectToDevice(QString &addr)
{
auto it = std::find_if(devices.begin(), devices.end(),
[&] (const QBluetoothDeviceInfo& d) { return d.address().toString() == addr; });
if (it == devices.end())
return;
device = *it;
controller = QLowEnergyController::createCentral(device, this);
connect(controller, &QLowEnergyController::serviceDiscovered, this, &BluetoothConnector::serviceDiscovered);
connect(controller, &QLowEnergyController::discoveryFinished, this, &BluetoothConnector::serviceScanDone);
connect(controller, static_cast<void (QLowEnergyController::*)(QLowEnergyController::Error)>(&QLowEnergyController::error),
this, [this](QLowEnergyController::Error error) {
Q_UNUSED(error);
qDebug() << "Controller error: " << error;
emit controllerError();
});
connect(controller, &QLowEnergyController::connected, this, [this]() {
qDebug() << "Controller connected. Search services...";
controller->discoverServices();
});
connect(controller, &QLowEnergyController::disconnected, this, [this]() {
qDebug() << "LowEnergy controller disconnected";
});
controller->connectToDevice();
}
void BluetoothConnector::configureDiscoveryAgent()
{
agent = new QBluetoothDeviceDiscoveryAgent(this);
agent->setLowEnergyDiscoveryTimeout(5000);
connect(agent, &QBluetoothDeviceDiscoveryAgent::deviceDiscovered, this, &BluetoothConnector::addDevice);
connect(agent, static_cast<void (QBluetoothDeviceDiscoveryAgent::*)(QBluetoothDeviceDiscoveryAgent::Error)>(&QBluetoothDeviceDiscoveryAgent::error),
this, &BluetoothConnector::scanError);
connect(agent, &QBluetoothDeviceDiscoveryAgent::finished, this, &BluetoothConnector::scanFinished);
connect(agent, &QBluetoothDeviceDiscoveryAgent::canceled, this, &BluetoothConnector::scanFinished);
}
void BluetoothConnector::addDevice(const QBluetoothDeviceInfo &info)
{
if (!devices.contains(info)) {
qDebug() << "Found device: " << info.name();
devices.append(info);
emit deviceFound(info);
}
}
void BluetoothConnector::scanError(QBluetoothDeviceDiscoveryAgent::Error error)
{
qDebug() << "Scan error: " << error;
}
void BluetoothConnector::scanFinished()
{
emit scanFinishedSignal();
}
void BluetoothConnector::serviceDiscovered(const QBluetoothUuid &newService)
{
qDebug() << "Service discovered: " << newService.toString();
if (newService == QBluetoothUuid(nodeServiceUUID)) {
nodeService = controller->createServiceObject(QBluetoothUuid(nodeServiceUUID), this);
qDebug() << "State: " << nodeService->state();
if (nodeService) {
qDebug() << "Node service created";
connect(nodeService, &QLowEnergyService::stateChanged, this, &BluetoothConnector::serviceStateChanged);
connect(nodeService, &QLowEnergyService::characteristicChanged, this, &BluetoothConnector::updateCharacteristic);
connect(nodeService, &QLowEnergyService::characteristicWritten, this, &BluetoothConnector::characteristicWritten);
connect(nodeService, QOverload<QLowEnergyService::ServiceError>::of(&QLowEnergyService::error),
[=](QLowEnergyService::ServiceError newError){ qDebug() << newError; });
//connect(nodeService, &QLowEnergyService::descriptorWritten, this, &BLTest::confirmedDescriptorWrite);
nodeService->discoverDetails();
} else {
qDebug() << "Node service not found.";
}
}
}
void BluetoothConnector::serviceScanDone()
{
qDebug() << "Services scan done";
}
void BluetoothConnector::characteristicWritten(const QLowEnergyCharacteristic &info, const QByteArray &value)
{
qDebug() << "Characteristic written: " << info.name();
}
void BluetoothConnector::serviceStateChanged(QLowEnergyService::ServiceState newState)
{
qDebug() << "State changed: " << newState;
if (newState == QLowEnergyService::ServiceDiscovered) {
qDebug() << "Service discovered";
const QLowEnergyCharacteristic networkIdChar = nodeService->characteristic(QBluetoothUuid(networkIdUUID));
const QLowEnergyCharacteristic dataModeChar = nodeService->characteristic(QBluetoothUuid(dataModeUUID));
const QLowEnergyCharacteristic locationChar = nodeService->characteristic(QBluetoothUuid(locationUUID));
if (networkIdChar.isValid() && dataModeChar.isValid() && locationChar.isValid()) {
auto idValue = networkIdChar.value();
auto modeValue = dataModeChar.value();
auto locValue = locationChar.value();
qDebug() << "Network ID: " << idValue;
qDebug() << "Mode: " << modeValue;
qDebug() << "Location: " << locValue;
auto notificationDesc = locationChar.descriptor(QBluetoothUuid::ClientCharacteristicConfiguration);
if (notificationDesc.isValid()) {
qDebug() << "Notification desc valid";
nodeService->writeDescriptor(notificationDesc, QByteArray::fromHex("0100"));
}
} else {
qDebug() << "Characteristic invalid";
}
}
}
void BluetoothConnector::updateCharacteristic(const QLowEnergyCharacteristic &info, const QByteArray &value)
{
if (info.uuid() == QBluetoothUuid(networkIdUUID)) {
qDebug() << "Update ID: " << value;
} else if (info.uuid() == QBluetoothUuid(dataModeUUID)) {
qDebug() << "Update mode: " << value;
} else if (info.uuid() == QBluetoothUuid(locationUUID)) {
qDebug() << "Update location: " << value;
}
}
解决方案
我认为,问题出在远程端(您的 GATT 服务器)。检查QLowEnergyService::error()
andQLowEnergyService::charcteristicWritten()
信号,看看你是否得到任何响应。您在远程端使用什么样的蓝牙堆栈?可能是,由于实施失败,您无权更改 CCCD。请检查远程端的实现。
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