Listener interfaces

The stack communicates with your application exclusively through three small interfaces. Your device class typically implements all three (multiple inheritance next to CoSlave/CoMaster) and passes *this to the constructor — but they can just as well live in separate objects.

ICoSendHandlerListener

Source/Common/ICoSendHandlerListener.hpp — the stack’s only way out to the hardware:

virtual bool SendCanMessage(const CANoopEn::CoCanMessage& canMessage) = 0;

Forward the frame to your CAN driver and return true on success. This is the complete CAN driver binding — reception is your side calling Proceed(msg).

ICoObjectDictionaryListener

Source/ObjectDictionary/ICoObjectDictionaryListener.hpp — passed to your CoObjectDictionary:

virtual void OnValueChanged(uint16_t nodeId, uint16_t index, uint16_t subIndex) = 0;

Called whenever an object’s value changes — e.g. a received RPDO wrote the digital outputs, or a remote SDO write changed a parameter. This is where your application reacts to incoming process values:

void MyDevice::OnValueChanged(uint16_t nodeId, uint16_t index, uint16_t subIndex)
{
    if (index == 0x6200 && subIndex == 0x01)      // digital outputs written via RPDO
    {
        uint8_t outputs;
        _objectDictionary.GetValue(index, subIndex, outputs);
        LedDriver::Set(outputs);
    }
}

ICoListener

Source/Common/ICoListener.hpp — all stack events. Callbacks belonging to a disabled feature (CoConfiguration) disappear from the interface, so a minimal build only implements what remains.

Always present

Callback	When
`OnDebugOutput(const char* formatSpecifiers, ...)`	The stack traces an event (printf-style). Route it to a UART/log, or leave the body empty.
`OnNmtStateChange(uint16_t nodeId, CoNmtState nmtState)`	A node’s NMT state changed — the local node on NMT commands, remote nodes (master) on boot-up/heartbeat evaluation.
`OnNmtCommand(uint16_t nodeId, CoNmtCommand nmtCommand)`	An NMT command was processed.

Feature-dependent

Callback	Switch	When
`OnIndicatorChanged(bool errorLedState, bool runLedState)`	`CO_ENABLE_INDICATORS`	The CiA 303-3 flash patterns (flickering, blinking, single/double/triple flash) are computed by the stack; you receive the resulting physical on/off state — just drive the two LED outputs.
`OnHeartbeatTimeout(uint16_t nodeId)`	`CO_ENABLE_HEARTBEAT`	A monitored node’s heartbeat stayed away longer than its consumer heartbeat time.
`OnSdoAbort(uint16_t nodeId, CoSdoAbortCode abortCode, uint16_t index, uint16_t subIndex)`	SDO server or client	An SDO transfer was aborted (either side).
`OnEmergency(uint16_t nodeId, CoEmcyErrorCode errorCode, uint8_t errorRegister, const uint8_t* errorField)`	`CO_ENABLE_EMCY`	An EMCY message was received (`errorField`: 5 manufacturer-specific bytes).
`OnSync(uint16_t nodeId, uint8_t counter)`	`CO_ENABLE_SYNC`	A SYNC message was processed (`counter` 0 if the message carried none).
`OnTime(uint16_t nodeId, uint32_t milliseconds, uint16_t days)`	`CO_ENABLE_TIME`	A TIME message was received (ms after midnight, days since 1984-01-01).

LSS (`CO_ENABLE_LSS`)

Slave-role requests — the application must actually perform what was requested:

Callback	When
`OnLssConfigureBitTimingRequest(uint16_t nodeId, uint8_t tableSelector, uint8_t tableIndex)`	The node’s bit timing was configured via LSS; apply the new bit rate to your CAN controller.
`OnLssStoreConfigurationRequest(uint16_t nodeId)`	The node shall persist its LSS configuration; write it to non-volatile memory.

Master-role responses to the CoMaster LSS requests:

Callback	Answers
`OnLssSwitchModeSelectiveConfirmed(uint16_t nodeId)`	`SwitchLssStateSelective`
`OnLssConfigureNodeIdResponse(uint16_t nodeId, uint8_t errorCode)`	`ConfigureLssNodeId` (0 = success)
`OnLssConfigureBitTimingResponse(uint16_t nodeId, uint8_t errorCode)`	`ConfigureLssBitTiming` (0 = success)
`OnLssStoreConfigurationResponse(uint16_t nodeId, uint8_t errorCode)`	`StoreLssConfiguration` (0 = success)
`OnLssInquireIdentityResponse(uint16_t nodeId, CoLssCommand command, uint32_t value)`	`InquireLssIdentity`
`OnLssInquireNodeIdResponse(uint16_t nodeId, uint8_t responseNodeId)`	`InquireLssNodeId`

CoCanMessage

Source/Common/CoCanMessage.hpp — the frame type used on both sides of the driver boundary. Constructors take the CAN identifier and up to eight data bytes; accessors: GetId/SetId, GetRtr/SetRtr, GetDataLength/SetDataLength, GetData(byteNumber)/SetData(byteNumber, value), Clear. Converting between CoCanMessage and your CAN controller’s frame format is a few lines in the driver (see the sample CanDriver implementations).