- Qt 6.6
- Qt Serial Bus
- C++ Classes
- Filter
- Qt 6.6.1 Reference Documentation

# Filter Struct

struct QCanBusDevice::Filter

The QCanBusDevice::Filter struct defines a filter for CAN bus frames. More...

- List of all members, including inherited members

## Public Types

enum | FormatFilter { MatchBaseFormat, MatchExtendedFormat, MatchBaseAndExtendedFormat }
flags | FormatFilters

## Public Variables

QCanBusDevice::Filter::FormatFilter | format
QCanBusFrame::FrameId | frameId
QCanBusFrame::FrameId | frameIdMask
QCanBusFrame::FrameType | type

## Related Non-Members

bool | operator!=(const Filter &a, const Filter &b)
bool | operator==(const Filter &a, const Filter &b)

## Detailed Description

A list of QCanBusDevice::Filter instances is passed to QCanBusDevice::setConfigurationParameter() to enable filtering. If a received CAN frame matches at least one of the filters in the list, the QCanBusDevice will accept it.

The example below demonstrates how to use the struct:

     QCanBusDevice::Filter filter;
     QList<QCanBusDevice::Filter> filterList;

     // filter all CAN bus packages with id 0x444 (base) or 0xXXXXX444 (extended)
     filter.frameId = 0x444u;
     filter.frameIdMask = 0x7FFu;
     filter.format = QCanBusDevice::Filter::MatchBaseAndExtendedFormat;
     filter.type = QCanBusFrame::InvalidFrame;
     filterList.append(filter);

     // filter all DataFrames with extended CAN bus package format
     filter.frameId = 0x0;
     filter.frameIdMask = 0x0;
     filter.format = QCanBusDevice::Filter::MatchExtendedFormat;
     filter.type = QCanBusFrame::DataFrame;
     filterList.append(filter);

     // apply filter
     device->setConfigurationParameter(QCanBusDevice::RawFilterKey, QVariant::fromValue(filterList));

## Member Type Documentation

### enum Filter::FormatFilter
flags Filter::FormatFilters

This enum describes the format pattern, which is used to filter incoming CAN bus frames.

Constant | Value | Description
--- | --- | ---
`QCanBusDevice::Filter::MatchBaseFormat` | `0x0001` | The CAN bus frame must use the base frame format (11 bit identifier).
`QCanBusDevice::Filter::MatchExtendedFormat` | `0x0002` | The CAN bus frame must use the extended frame format (29 bit identifier).
`QCanBusDevice::Filter::MatchBaseAndExtendedFormat` | `0x0003` | The CAN bus frame can have a base or an extended frame format.

The FormatFilters type is a typedef for QFlags<FormatFilter>. It stores an OR combination of FormatFilter values.

## Member Variable Documentation

### QCanBusDevice::Filter::FormatFilter Filter::format

This variable holds the frame format of the matching CAN bus frame.

By default this field is set to QCanBusDevice::Filter::MatchBaseAndExtendedFormat.

### QCanBusFrame::FrameId Filter::frameId

This variable holds the frame id used to filter the incoming frames.

The frameId is used in conjunction with frameIdMask. The matching is successful if the following evaluates to `true`:

     (receivedFrameId & frameIdMask) == (frameId & frameIdMask)

By default this field is set to `0x0`.

See also frameIdMask.

### QCanBusFrame::FrameId Filter::frameIdMask

This variable holds the bit mask that is applied to the frame id of the filter and the received frame.

The two frame ids are matching if the following evaluates to `true`:

     (receivedFrameId & frameIdMask) == (frameId & frameIdMask)

By default this field is set to `0x0`.

See also frameId.

### QCanBusFrame::FrameType Filter::type

This variable holds the type of the frame to be filtered.

Any CAN bus frame type can be matched by setting this variable to QCanBusFrame::InvalidFrame. The filter object is invalid if type is equal to QCanBusFrame::UnknownFrame.

By default this field is set to QCanBusFrame::InvalidFrame.

See also QCanBusFrame::FrameType.

## Related Non-Members

### `[constexpr noexcept]` bool operator!=(const Filter &a, const Filter &b)

Returns `true`, if the filter a is not equal to the filter b, otherwise returns `false`.

### `[constexpr noexcept]` bool operator==(const Filter &a, const Filter &b)

Returns `true`, if the filter a is equal to the filter b, otherwise returns `false`.