The QCanBusDevice class is the interface class for CAN bus. 更多...
| 头： | #include <QCanBusDevice> |
| qmake: | QT += serialbus |
| Since: | Qt 5.8 |
| 继承： | QObject |
| class | Filter |
| enum | CanBusDeviceState { UnconnectedState, ConnectingState, ConnectedState, ClosingState } |
| enum | CanBusError { NoError, ReadError, WriteError, ConnectionError, ConfigurationError, UnknownError } |
| enum | ConfigurationKey { RawFilterKey, ErrorFilterKey, LoopbackKey, ReceiveOwnKey, ..., UserKey } |
| QCanBusDevice (QObject * parent = nullptr) | |
| QVector<int> | configurationKeys () const |
| QVariant | configurationParameter (int key ) const |
| bool | connectDevice () |
| void | disconnectDevice () |
| CanBusError | error () const |
| QString | errorString () const |
| qint64 | framesAvailable () const |
| qint64 | framesToWrite () const |
| virtual QString | interpretErrorFrame (const QCanBusFrame & frame ) = 0 |
| QCanBusFrame | readFrame () |
| virtual void | setConfigurationParameter (int key , const QVariant & value ) |
| CanBusDeviceState | state () const |
| virtual bool | waitForFramesReceived (int msecs ) |
| virtual bool | waitForFramesWritten (int msecs ) |
| virtual bool | writeFrame (const QCanBusFrame & frame ) = 0 |
| void | errorOccurred (QCanBusDevice::CanBusError error ) |
| void | framesReceived () |
| void | framesWritten (qint64 framesCount ) |
| void | stateChanged (QCanBusDevice::CanBusDeviceState state ) |
| virtual void | close () = 0 |
| QCanBusFrame | dequeueOutgoingFrame () |
| void | enqueueOutgoingFrame (const QCanBusFrame & newFrame ) |
| void | enqueueReceivedFrames (const QVector<QCanBusFrame> & newFrames ) |
| bool | hasOutgoingFrames () const |
| virtual bool | open () = 0 |
| void | setError (const QString & errorText , QCanBusDevice::CanBusError errorId ) |
| void | setState (QCanBusDevice::CanBusDeviceState newState ) |
The QCanBusDevice class is the interface class for CAN bus.
QCanBusDevice communicates with a CAN plugin providing users with a convenient API. The CAN plugin must be specified during the object creation.
此枚举描述所有可能的设备状态。
| 常量 | 值 | 描述 |
|---|---|---|
QCanBusDevice::UnconnectedState
|
0
|
设备已断开连接。 |
QCanBusDevice::ConnectingState
|
1
|
设备正在连接。 |
QCanBusDevice::ConnectedState
|
2
|
设备已连接到 CAN Bus。 |
QCanBusDevice::ClosingState
|
3
|
设备正在关闭。 |
此枚举描述所有可能的错误条件。
| 常量 | 值 | 描述 |
|---|---|---|
QCanBusDevice::NoError
|
0
|
没有发生错误。 |
QCanBusDevice::ReadError
|
1
|
An error occurred during a read operation. |
QCanBusDevice::WriteError
|
2
|
An error occurred during a write operation. |
QCanBusDevice::ConnectionError
|
3
|
An error occurred when attempting to open the plugin. |
QCanBusDevice::ConfigurationError
|
4
|
An error occurred when attempting to set a configuration parameter. |
QCanBusDevice::UnknownError
|
5
|
出现未知错误。 |
This enum describes the possible configuration options for the CAN bus connection.
| 常量 | 值 | 描述 |
|---|---|---|
QCanBusDevice::RawFilterKey
|
0
|
This configuration determines the type of CAN bus frames that the current device accepts. The expected value is
QList<QCanBusDevice::Filter>
. Passing an empty list clears all previously set filters including default filters. For more details see
QCanBusDevice::Filter
.
|
QCanBusDevice::ErrorFilterKey
|
1
|
This key defines the type of error that should be forwarded via the current connection. The associated value should be of type QCanBusFrame::FrameErrors . |
QCanBusDevice::LoopbackKey
|
2
|
This key defines whether the CAN bus device should operate in loopback mode. Loopback means, whenever a CAN frame is transmitted on the CAN bus, a local echo of this frame is sent to all applications connected to this CAN device. The expected value for this key is
bool
.
|
QCanBusDevice::ReceiveOwnKey
|
3
|
This key defines whether this CAN device receives its own send frames. This can be used to check if the transmission was successful. The expected value for this key is
bool
.
|
QCanBusDevice::BitRateKey
|
4
|
This key defines the CAN bitrate in bits per second. With CAN FD, the payload can be transmitted at a higher data bitrate, if
QCanBusFrame::hasBitrateSwitch
() is set. In this case,
QCanBusDevice::BitRateKey
is only used for the CAN ID arbitration phase. See also
QCanBusDevice::DataBitRateKey
|
QCanBusDevice::CanFdKey
|
5
|
This key defines whether sending and receiving of CAN FD frames should be enabled. The expected value for this key is
bool
.
|
QCanBusDevice::DataBitRateKey
|
6
|
This key defines the CAN FD payload bitrate in bits per second. CAN FD allows to transmit the payload of frames with
QCanBusFrame::hasBitrateSwitch
() flag at a higher data bitrate, after the arbitration phase at the nominal bitrate is finished. This enum value was introduced in Qt 5.9. See also
QCanBusDevice::BitRateKey
|
QCanBusDevice::UserKey
|
30
|
This key defines the range where custom keys start. Its most common purpose is to permit platform-specific configuration options. |
另请参阅 configurationParameter ().
构造串行总线设备采用指定 parent .
[pure virtual protected]
void
QCanBusDevice::
close
()
This function is responsible for closing the CAN bus connection. The implementation must ensure that the instance's state () 被设为 QCanBusDevice::UnconnectedState .
This function's most important task is to close the socket to the CAN device and to call QCanBusDevice::setState ().
另请参阅 disconnectDevice ().
Returns the list of keys used by the CAN bus connection.
The the meaning of the keys is equivalent to ConfigurationKey . If a key is not explicitly mentioned the platform's default setting for the relevant key is used.
Returns the current value assigned to the ConfigurationKey key ; otherwise an invalid QVariant .
另请参阅 setConfigurationParameter () 和 configurationKeys ().
将设备连接到 CAN (控制器局域网) 总线。返回
true
当成功时；否则
false
.
此函数调用 open () 作为其实现的一部分。
另请参阅 disconnectDevice ().
[protected]
QCanBusFrame
QCanBusDevice::
dequeueOutgoingFrame
()
返回下一 QCanBusFrame from the internal list of outgoing frames; otherwise returns an invalid QCanBusFrame . The returned frame is removed from the internal list.
从 CAN (控制器局域网) 总线断开设备连接。
此函数调用 close () 作为其实现的一部分。
注意：
This function should only be called, if
connectDevice
() 返回
true
.
另请参阅 connectDevice ().
[protected]
void
QCanBusDevice::
enqueueOutgoingFrame
(const
QCanBusFrame
&
newFrame
)
追加 newFrame to the internal list of outgoing frames which can be accessed by writeFrame ().
Subclasses must call this function when they write a new frame.
[protected]
void
QCanBusDevice::
enqueueReceivedFrames
(const
QVector
<
QCanBusFrame
> &
newFrames
)
追加 newFrames to the internal list of frames which can be accessed using readFrame () and emits the framesReceived () 信号。
Subclasses must call this function when they receive frames.
Returns the last error that has occurred. The error value is always set to last error that occurred and it is never reset.
另请参阅 setError () 和 errorString ().
[signal]
void
QCanBusDevice::
errorOccurred
(
QCanBusDevice::CanBusError
error
)
This signal is emitted when an error of the type error 出现。
返回人类可读的最后发生的设备错误描述。
另请参阅 error ().
Returns the number of available frames. If no frames are available, this function returns 0.
另请参阅 readFrame ().
[signal]
void
QCanBusDevice::
framesReceived
()
This signal is emitted when one or more frames have been received. The frames should be read using readFrame () 和 framesAvailable ().
For buffered devices, this function returns the number of frames waiting to be written. For unbuffered devices, this function always returns zero.
注意： There may be additional buffering in the CAN driver and CAN hardware layer. Therefore, if this function returns zero, that does not mean all CAN frames are already written to the CAN bus.
另请参阅 writeFrame ().
[signal]
void
QCanBusDevice::
framesWritten
(
qint64
framesCount
)
This signal is emitted every time a payload of frames has been written to the CAN bus. The framesCount argument is set to the number of frames that were written in this payload.
[protected]
bool
QCanBusDevice::
hasOutgoingFrames
() const
返回
true
if the internal list of outgoing frames is not empty; otherwise returns
false
.
[pure virtual]
QString
QCanBusDevice::
interpretErrorFrame
(const
QCanBusFrame
&
frame
)
Interprets frame as error frame and returns a human readable description of the error.
若 frame is not an error frame, the returned string is empty.
[pure virtual protected]
bool
QCanBusDevice::
open
()
此函数被调用通过
connectDevice
(). Subclasses must provide an implementation which returns
true
if the CAN bus connection could be established; otherwise
false
。
QCanBusDevice
implementation ensures upon entry of this function that the device's
state
() 被设为
QCanBusDevice::ConnectingState
already.
The implementation must ensure that upon success the instance's state () 被设为 QCanBusDevice::ConnectedState ；否则 QCanBusDevice::UnconnectedState . setState () must be used to set the new device state.
The custom implementation is responsible for opening the socket, instanciation of a potentially required QSocketNotifier and the application of custom and default QCanBusDevice::configurationParameter ().
另请参阅 connectDevice ().
返回下一 QCanBusFrame from the queue; otherwise returns an empty QCanBusFrame . The returned frame is removed from the queue.
The queue operates according to the FIFO principle.
另请参阅 framesAvailable ().
[虚拟]
void
QCanBusDevice::
setConfigurationParameter
(
int
key
, const
QVariant
&
value
)
Sets the configuration parameter key for the CAN bus connection to value . The potential keys are represented by ConfigurationKey .
A parameter can be unset by setting an invalid QVariant . Unsetting a parameter implies that the configuration is reset to its default setting.
注意： In most cases, configuration changes only take effect after a reconnect.
另请参阅 configurationParameter ().
[protected]
void
QCanBusDevice::
setError
(const
QString
&
errorText
,
QCanBusDevice::CanBusError
errorId
)
Sets the human readable description of the last device error to errorText . errorId categorizes the type of error.
CAN bus implementations must use this function to update the device's error state.
另请参阅 error () 和 errorOccurred ().
[protected]
void
QCanBusDevice::
setState
(
QCanBusDevice::CanBusDeviceState
newState
)
Sets the state of the device to newState . CAN bus implementations must use this function to update the device state.
另请参阅 state ().
返回设备的当前状态。
另请参阅 setState () 和 stateChanged ().
[signal]
void
QCanBusDevice::
stateChanged
(
QCanBusDevice::CanBusDeviceState
state
)
This signal is emitted every time the state of the device changes. The new state is represented by state .
[虚拟]
bool
QCanBusDevice::
waitForFramesReceived
(
int
msecs
)
Blocks until new frames are available for reading and the
framesReceived
() 信号已发射，或直到
msecs
毫秒已过去。若
msecs
is
-1
，此函数不会超时。
返回
true
if new frames are available for reading and the
framesReceived
() signal is emitted; otherwise returns
false
(若操作超时或发生错误)。
注意： This function will start a local event loop. This may lead to scenarios whereby other application slots may be called while the execution of this function scope is blocking. To avoid problems, the signals for this class should not be connected to slots. Similarly this function must never be called in response to the framesReceived () 或 errorOccurred () 信号。
另请参阅 waitForFramesWritten ().
[虚拟]
bool
QCanBusDevice::
waitForFramesWritten
(
int
msecs
)
For buffered devices, this function waits until all buffered frames have been written to the device and the
framesWritten
() 信号已发射，或直到
msecs
毫秒已过去。若
msecs
is -1, this function will not time out. For unbuffered devices, it returns immediately with
false
as
writeFrame
() does not require a write buffer.
返回
true
若
framesWritten
() signal is emitted; otherwise returns
false
（即：若操作超时或发生错误)。
注意： This function will start a local event loop. This may lead to scenarios whereby other application slots may be called while the execution of this function scope is blocking. To avoid problems, the signals for this class should not be connected to slots. Similarly this function must never be called in response to the framesWritten () 或 errorOccurred () 信号。
另请参阅 waitForFramesReceived ().
[pure virtual]
bool
QCanBusDevice::
writeFrame
(const
QCanBusFrame
&
frame
)
写入
frame
到 CAN (控制器局域网) 总线并返回
true
当成功时；否则
false
.
On some platforms, the frame may be put into a queue and the return value may only indicate a successful insertion into the queue. The actual frame will be send later on. Therefore the framesWritten () signal is the final confirmation that the frame has been handed off to the transport layer. If an error occurs the errorOccurred () 被发射。
As per CAN bus specification, frames of type remote transfer request (RTR) do not have a payload, but a length from 0 to 8 (including). This length indicates the expected response payload length from the remote party. Therefore when sending a RTR frame using this function it may still be required to set an arbitrary payload on frame . The length of the arbitrary payload is what is set as size expectation for the RTR frame.
另请参阅 QCanBusFrame::setPayload ().