tap::can::CanRxHandler Class Reference

#include <can_rx_handler.hpp>

Collaboration diagram for tap::can::CanRxHandler:

Public Member Functions
	CanRxHandler (Drivers *drivers)
mockable	~CanRxHandler ()=default
mockable void	attachReceiveHandler (CanRxListener *const listener)
mockable void	pollCanData ()
mockable void	removeReceiveHandler (const CanRxListener &rxListener)

Static Public Member Functions
static uint16_t	binIndexForCanId (uint16_t canId)

Static Public Attributes
static constexpr uint8_t	CAN_BINS = 8

Protected Member Functions
void	attachReceiveHandler (CanRxListener *const canRxListener, CanRxListener **messageHandlerStore)
void	processReceivedCanData (const modm::can::Message &rxMessage, CanRxListener *const *messageHandlerStore)
void	removeReceiveHandler (const CanRxListener &canRxListener, CanRxListener **messageHandlerStore)
CanRxListener **	getHandlerStore (CanBus bus)

Protected Attributes
Drivers *	drivers
CanRxListener *	messageHandlerStoreCan1 [CAN_BINS]
CanRxListener *	messageHandlerStoreCan2 [CAN_BINS]

Detailed Description

A handler that stores pointers to CanRxListener and that watches CAN 1 and CAN 2 for messages. If messages are received, it checks its internal maps for a CanRxListener that matches the message identifier and CAN bus and calls the listener's processMessage function.

Interfaces with modm receive data from CAN1 and CAN2 buses.

To use, extend CanRxListener class and create a method called processMessage. Next, call the function attachReceiveHandler, which will add the class you instantiated to a list of classes that will be handled on receive. The class you created and attached will be called by the pollCanData function every time there is a message available that has the CAN identifier matching the identifier specified in the CanRxListener constructor.

For proper closed loop motor control, it is necessary to have the pollCanData function be called at a very high frequency, so call this in a high frequency thread.

Note

CAN ids [0x201, 0x20B] are used by the DjiMotor objects to receive data from DJI branded motors. If you would like to define your own protocol, it is recommended to avoid avoid using CAN ids in this range.

the DjiMotor driver reserves 0x1FF and 0x200 for commanding motors, and thus you should not attach listeners for these ids.

See also

CanRxListener for information about how to properly create add a listener to the handler.

Can for modm CAN wrapper functions.

Constructor & Destructor Documentation

CanRxHandler()

tap::can::CanRxHandler::CanRxHandler

(

Drivers *

drivers

)

~CanRxHandler()

mockable tap::can::CanRxHandler::~CanRxHandler ( )

default

Member Function Documentation

attachReceiveHandler() [1/2]

void tap::can::CanRxHandler::attachReceiveHandler ( CanRxListener *const  canRxListener, CanRxListener **  messageHandlerStore  )

protected

attachReceiveHandler() [2/2]

void tap::can::CanRxHandler::attachReceiveHandler

(

CanRxListener *const

listener

)

Call this function to add a CanRxListener to the list of CanRxListener's that are referenced when a new CAN message is received.

Note

do not call this function in an object that is globally (i.e. not on that stack or heap) constructed. The map that the handler uses to store listeners may or not be properly allocated if you do and undefined behavior will follow.

if you attempt to add a listener with an identifier identical to something already in the CanRxHandler, an error will be added to the ErrorController and the handler does not add the listener.

See also

CanRxListener

Parameters

[in]

listener

the listener to be attached ot the handler.

binIndexForCanId()

static uint16_t tap::can::CanRxHandler::binIndexForCanId ( uint16_t  canId )

inlinestatic

Given a CAN identifier, returns the bin index between [0, NUM_CAN_IDS) for the identifier.

getHandlerStore()

CanRxListener ** tap::can::CanRxHandler::getHandlerStore ( CanBus  bus )

inlineprotected

pollCanData()

void tap::can::CanRxHandler::pollCanData

(

)

Function handles receiving messages and calling the appropriate processMessage function given the CAN bus and can identifier.

Attention

you should call this function as frequently as you receive messages if you want to receive the most up to date messages. modm's IQR puts CAN messages in a queue, and this function clears out the queue once it is called.

processReceivedCanData()

void tap::can::CanRxHandler::processReceivedCanData ( const modm::can::Message &  rxMessage, CanRxListener *const *  messageHandlerStore  )

protected

removeReceiveHandler() [1/2]

void tap::can::CanRxHandler::removeReceiveHandler ( const CanRxListener &  canRxListener, CanRxListener **  messageHandlerStore  )

protected

removeReceiveHandler() [2/2]

void tap::can::CanRxHandler::removeReceiveHandler

(

const CanRxListener &

rxListener

)

Removes the passed in CanRxListener from the CanRxHandler. If the listener isn't in the handler, an error will be added to the ErrorController and the state of the CanRxHandler will not change.

Parameters

[in]

rxListener

The listener to remove from the handler.

Member Data Documentation

CAN_BINS

constexpr uint8_t tap::can::CanRxHandler::CAN_BINS = 8

staticconstexpr

The number of "hash" bins to store listeners in. 8 is choosen as most users will only have DJI Motors on their can bus, reducing any unnecessary overhead storing empty bins. The bus also become saturated near this limit, so the performance hit of a linked list traversal is minimal.

drivers

Drivers* tap::can::CanRxHandler::drivers

protected

messageHandlerStoreCan1

CanRxListener* tap::can::CanRxHandler::messageHandlerStoreCan1[CAN_BINS]

protected

Stores pointers to the CanRxListeners for CAN 1, referenced when a new message is received.

messageHandlerStoreCan2

CanRxListener* tap::can::CanRxHandler::messageHandlerStoreCan2[CAN_BINS]

protected

Stores pointers to the CanRxListeners for CAN 2, referenced when a new message is received.

---

The documentation for this class was generated from the following files:

• fang-mcb-project/taproot/src/tap/communication/can/can_rx_handler.hpp
• fang-mcb-project/taproot/src/tap/communication/can/can_rx_handler.cpp