CAN Interface

Driver API for CAN Bus Peripheral (Driver_CAN.h)

Content

Status Error Codes
Status codes of the CAN driver.
 
CAN Unit Events
Callback unit events notified via ARM_CAN_SignalUnitEvent.
 
CAN Object Events
Callback objects events notified via ARM_CAN_SignalObjectEvent.
 
CAN Control Codes
Codes to configure the CAN driver.
 

Data Structures

struct  ARM_DRIVER_CAN
 Access structure of the CAN Driver.
 
struct  ARM_CAN_CAPABILITIES
 CAN Device Driver Capabilities.
 
struct  ARM_CAN_STATUS
 CAN Status.
 
struct  ARM_CAN_MSG_INFO
 CAN Message Information.
 
struct  ARM_CAN_OBJ_CAPABILITIES
 CAN Object Capabilities.
 

Typedefs

typedef void(* ARM_CAN_SignalUnitEvent_t )(uint32_t event)
 Pointer to ARM_CAN_SignalUnitEvent : Signal CAN Unit Event.
 
typedef void(* ARM_CAN_SignalObjectEvent_t )(uint32_t obj_idx, uint32_t event)
 Pointer to ARM_CAN_SignalObjectEvent : Signal CAN Object Event.
 

Functions

ARM_DRIVER_VERSION ARM_CAN_GetVersion (void)
 Get driver version.
 
ARM_CAN_CAPABILITIES ARM_CAN_GetCapabilities (void)
 Get driver capabilities.
 
int32_t ARM_CAN_Initialize (ARM_CAN_SignalUnitEvent_t cb_unit_event, ARM_CAN_SignalObjectEvent_t cb_object_event)
 Initialize CAN interface and register signal (callback) functions.
 
int32_t ARM_CAN_Uninitialize (void)
 De-initialize CAN interface.
 
int32_t ARM_CAN_PowerControl (ARM_POWER_STATE state)
 Control CAN interface power.
 
uint32_t ARM_CAN_GetClock (void)
 Retrieve CAN base clock frequency.
 
int32_t ARM_CAN_SetBitrate (ARM_CAN_BITRATE_SELECT select, uint32_t bitrate, uint32_t bit_segments)
 Set bitrate for CAN interface.
 
int32_t ARM_CAN_SetMode (ARM_CAN_MODE mode)
 Set operating mode for CAN interface.
 
ARM_CAN_OBJ_CAPABILITIES ARM_CAN_ObjectGetCapabilities (uint32_t obj_idx)
 Retrieve capabilities of an object.
 
int32_t ARM_CAN_ObjectSetFilter (uint32_t obj_idx, ARM_CAN_FILTER_OPERATION operation, uint32_t id, uint32_t arg)
 Add or remove filter for message reception.
 
int32_t ARM_CAN_ObjectConfigure (uint32_t obj_idx, ARM_CAN_OBJ_CONFIG obj_cfg)
 Configure object.
 
int32_t ARM_CAN_MessageSend (uint32_t obj_idx, ARM_CAN_MSG_INFO *msg_info, const uint8_t *data, uint8_t size)
 Send message on CAN bus.
 
int32_t ARM_CAN_MessageRead (uint32_t obj_idx, ARM_CAN_MSG_INFO *msg_info, uint8_t *data, uint8_t size)
 Read message received on CAN bus.
 
int32_t ARM_CAN_Control (uint32_t control, uint32_t arg)
 Control CAN interface.
 
ARM_CAN_STATUS ARM_CAN_GetStatus (void)
 Get CAN status.
 
void ARM_CAN_SignalUnitEvent (uint32_t event)
 Signal CAN unit event.
 
void ARM_CAN_SignalObjectEvent (uint32_t obj_idx, uint32_t event)
 Signal CAN object event.
 

Description

Driver API for CAN Bus Peripheral (Driver_CAN.h)

The Controller Area Network Interface Bus (CAN) implements a multi-master serial bus for connecting microcontrollers and devices, also known as nodes, to communicate with each other in applications without a host computer. CAN is a message-based protocol, designed originally for automotive applications, but meanwhile used also in many other surroundings. The complexity of the node can range from a simple I/O device up to an embedded computer with a CAN interface and sophisticated software. The node may also be a gateway allowing a standard computer to communicate over a USB or Ethernet port to the devices on a CAN network. Devices are connected to the bus through a host processor, a CAN controller, and a CAN transceiver.

The CAN Driver API allows to implement CAN Interfaces that conform to the CAN specifications available from BOSCH:

  • CAN 2.0B: CAN Specification 2.0B (released Sep. 1991) which is now superseded by ISO 11898-1.
  • CAN FD: CAN with Flexible Data Rate introduced in 2012 (released April 17th, 2012).

Wikipedia offers more information about the CAN Bus.

CAN 2.0B** Every CAN CMSIS-Driver supports the CAN 2.0B standard

CAN 2.0B supports:

  • message can contain up to 8 data bytes
  • bitrates of up to 1Mbits/s
  • Remote Frame requests

CAN FD

Support for CAN FD depends on the hardware. A CMSIS-Driver that supports CAN FD has the capability ARM_CAN_CAPABILITIES data field fd_mode = 1, which can be retrieved with the function ARM_CAN_GetCapabilities.

CAN FD supports:

  • message can contain up to 64 data bytes
  • faster data transfers with faster bitrate used during the data phase

CAN FD does not support Remote Frame requests.

Block Diagram

The CAN Driver API defines a CAN interface for middleware components. The CAN Driver supports multiple nodes, which are able to send and receive messages, but not simultaneously.

CAN_Node.png
CAN Node Schematic

CAN API

The following header files define the Application Programming Interface (API) for the CAN interface:

  • Driver_CAN.h : Driver API for CAN Bus Peripheral

The driver implementation is a typical part of the Device Family Pack (DFP) that supports the peripherals of the microcontroller family.

Driver Functions

The driver functions are published in the access struct as explained in Common Driver Functions

Example Code

The following example code shows the usage of the CAN interface.

#include <stdio.h>
#include <string.h>
#include "cmsis_os.h"
#include "Driver_CAN.h"
// CAN Driver Controller selector
#define CAN_CONTROLLER 1 // CAN Controller number
#define _CAN_Driver_(n) Driver_CAN##n
#define CAN_Driver_(n) _CAN_Driver_(n)
extern ARM_DRIVER_CAN CAN_Driver_(CAN_CONTROLLER);
#define ptrCAN (&CAN_Driver_(CAN_CONTROLLER))
uint32_t rx_obj_idx = 0xFFFFFFFFU;
uint8_t rx_data[8];
ARM_CAN_MSG_INFO rx_msg_info;
uint32_t tx_obj_idx = 0xFFFFFFFFU;
uint8_t tx_data[8];
ARM_CAN_MSG_INFO tx_msg_info;
static void Error_Handler (void) { while (1); }
void CAN_SignalUnitEvent (uint32_t event) {}
void CAN_SignalObjectEvent (uint32_t obj_idx, uint32_t event) {
if (obj_idx == rx_obj_idx) { // If receive object event
if (event == ARM_CAN_EVENT_RECEIVE) { // If message was received successfully
if (ptrCAN->MessageRead(rx_obj_idx, &rx_msg_info, rx_data, 8U) > 0U) {
// Read received message
// process received message ...
}
}
}
if (obj_idx == tx_obj_idx) { // If transmit object event
if (event == ARM_CAN_EVENT_SEND_COMPLETE) { // If message was sent successfully
// acknowledge sent message ...
}
}
}
int main (void) {
int32_t status;
uint32_t i, num_objects;
can_cap = ptrCAN->GetCapabilities (); // Get CAN driver capabilities
num_objects = can_cap.num_objects; // Number of receive/transmit objects
status = ptrCAN->Initialize (CAN_SignalUnitEvent, CAN_SignalObjectEvent); // Initialize CAN driver
if (status != ARM_DRIVER_OK ) { Error_Handler(); }
status = ptrCAN->PowerControl (ARM_POWER_FULL); // Power-up CAN controller
if (status != ARM_DRIVER_OK ) { Error_Handler(); }
status = ptrCAN->SetMode (ARM_CAN_MODE_INITIALIZATION); // Activate initialization mode
if (status != ARM_DRIVER_OK ) { Error_Handler(); }
status = ptrCAN->SetBitrate (ARM_CAN_BITRATE_NOMINAL, // Set nominal bitrate
100000U, // Set bitrate to 100 kbit/s
ARM_CAN_BIT_PROP_SEG(5U) | // Set propagation segment to 5 time quanta
ARM_CAN_BIT_PHASE_SEG1(1U) | // Set phase segment 1 to 1 time quantum (sample point at 87.5% of bit time)
ARM_CAN_BIT_PHASE_SEG2(1U) | // Set phase segment 2 to 1 time quantum (total bit is 8 time quanta long)
ARM_CAN_BIT_SJW(1U)); // Resynchronization jump width is same as phase segment 2
if (status != ARM_DRIVER_OK ) { Error_Handler(); }
for (i = 0U; i < num_objects; i++) { // Find first available object for receive and transmit
can_obj_cap = ptrCAN->ObjectGetCapabilities (i); // Get object capabilities
if ((rx_obj_idx == 0xFFFFFFFFU) && (can_obj_cap.rx == 1U)) { rx_obj_idx = i; }
else if ((tx_obj_idx == 0xFFFFFFFFU) && (can_obj_cap.tx == 1U)) { tx_obj_idx = i; break; }
}
if ((rx_obj_idx == 0xFFFFFFFFU) || (tx_obj_idx == 0xFFFFFFFFU)) { Error_Handler(); }
// Set filter to receive messages with extended ID 0x12345678 to receive object
status = ptrCAN->ObjectSetFilter(rx_obj_idx, ARM_CAN_FILTER_ID_EXACT_ADD, ARM_CAN_EXTENDED_ID(0x12345678U), 0U);
if (status != ARM_DRIVER_OK ) { Error_Handler(); }
status = ptrCAN->ObjectConfigure(tx_obj_idx, ARM_CAN_OBJ_TX); // Configure transmit object
if (status != ARM_DRIVER_OK ) { Error_Handler(); }
status = ptrCAN->ObjectConfigure(rx_obj_idx, ARM_CAN_OBJ_RX); // Configure receive object
if (status != ARM_DRIVER_OK ) { Error_Handler(); }
status = ptrCAN->SetMode (ARM_CAN_MODE_NORMAL); // Activate normal operation mode
if (status != ARM_DRIVER_OK ) { Error_Handler(); }
memset(&tx_msg_info, 0U, sizeof(ARM_CAN_MSG_INFO)); // Clear message info structure
tx_msg_info.id = ARM_CAN_EXTENDED_ID(0x12345678U); // Set extended ID for transmit message
tx_data[0] = 0xFFU; // Initialize transmit data
while (1) {
tx_data[0]++; // Increment transmit data
status = ptrCAN->MessageSend(tx_obj_idx, &tx_msg_info, tx_data, 1U); // Send data message with 1 data byte
if (status != 1U) { Error_Handler(); }
for (i = 0U; i < 1000000U; i++) { __nop(); } // Wait a little while
}
}

CAN Message Objects

The CMSIS-Driver for the CAN interface provides multiple CAN message objects, which can be seen as individual communication channels. The number of available CAN message objects depends on the CAN peripheral. The function ARM_CAN_GetCapabilities returns the maximum number of available CAN message objects. The number is encoded in the structure ARM_CAN_CAPABILITIES in the data field num_objects. CAN message objects are addressed with the functions listed below, whereby the parameter obj_idx addresses an individual object. The valid range for obj_idx is [0 .. (num_objects - 1)].

Function Description
ARM_CAN_ObjectGetCapabilities Retrieves message object capabilities such as receive, transmit, Remote Frame automatic handling and CAN Message Filtering.
ARM_CAN_ObjectSetFilter Allows to set-up CAN ID filtering for the message object.
ARM_CAN_ObjectConfigure Allows to configure the message object for receive, transmit or Remote Frame automatic handling.
ARM_CAN_MessageRead Read received message from the message object.
ARM_CAN_MessageSend Send CAN message or send Remote Frame or set CAN message to be sent automatically on reception of matching Remote Frame on the message object.
ARM_CAN_SignalObjectEvent Callback function that signals a message transfer or a received message overrun.

Each CAN message object may have different capabilities. Before using a CAN message object, call the function ARM_CAN_ObjectGetCapabilities to verify the available features.

CAN Message Filtering

The CMSIS-Driver for the CAN interface supports ID filtering for the receiving message objects. The receiving CAN node examines the identifier to decide if it was relevant. This filtering is done by the CAN peripheral according the settings configured with the function ARM_CAN_ObjectSetFilter.

The function ARM_CAN_ObjectGetCapabilities retrieves the filter capabilities of the CAN message objects stored in ARM_CAN_OBJ_CAPABILITIES.

Data Fields CAN Messages Object can be filtered with ...
exact_filtering an exact ID value set by using the function ARM_CAN_ObjectSetFilter with control = ARM_CAN_FILTER_ID_EXACT_ADD.
range_filtering a range ID value set by using the function ARM_CAN_ObjectSetFilter with control = ARM_CAN_FILTER_ID_RANGE_ADD.
mask_filtering a mask ID value set by as using the function ARM_CAN_ObjectSetFilter with control = ARM_CAN_FILTER_ID_MASKABLE_ADD.
multiple_filters ... several filters to capture multiple ID values, or ID value ranges.

CAN message filtering using an exact ID

Example: accept in message object #1 only frames with extended ID = 0x1567.

status = ptrCAN->ObjectSetFilter (1, ARM_CAN_FILTER_ID_EXACT_ADD, ARM_CAN_EXTENDED_ID(0x1567), 0);
if (status != ARM_DRIVER_OK) ... // error handling

Example: accept in message object #2 frames with extended ID = 0x3167 and extended ID = 0x42123.

status = ptrCAN->ObjectSetFilter (2, ARM_CAN_FILTER_ID_EXACT_ADD, ARM_CAN_EXTENDED_ID(0x3167), 0);
if (status != ARM_DRIVER_OK) ... // error handling
status = ptrCAN->ObjectSetFilter (2, ARM_CAN_FILTER_ID_EXACT_ADD, ARM_CAN_EXTENDED_ID(0x42123), 0);
if (status != ARM_DRIVER_OK) ... // error handling

CAN message filtering using a range ID

Example: accept in message object #3 only frames with extended ID >= 0x1567 and extended ID <= 0x1577.

status = ptrCAN->ObjectSetFilter (3, ARM_CAN_FILTER_ID_RANGE_ADD, ARM_CAN_EXTENDED_ID(0x1567), ARM_CAN_EXTENDED_ID(0x1577));
if (status != ARM_DRIVER_OK) ... // error handling

CAN message filtering using a mask ID

Using the function ARM_CAN_ObjectSetFilter with control = ARM_CAN_FILTER_ID_MASKABLE_ADD allows to specify with arg a mask value.

  • if a mask bit is 0, the corresponding ID bit will be accepted, regardless of the value.
  • if a mask bit is 1, the corresponding ID bit will be compared with the value of the ID filter bit; if they match the message will be accepted otherwise the frame is rejected.

Example: accept in message object #0 only frames with extended IDs 0x1560 to 0x156F.

status = ptrCAN->ObjectSetFilter (0, ARM_CAN_FILTER_ID_MASKABLE_ADD, ARM_CAN_EXTENDED_ID(0x1560), 0x1FFFFFF0);
if (status != ARM_DRIVER_OK) ... // error handling

Example: accept in message object #2 only frames with extended IDs 0x35603, 0x35613, 0x35623, and 0x35633.

status = ptrCAN->ObjectSetFilter (2, ARM_CAN_FILTER_ID_MASKABLE_ADD, ARM_CAN_EXTENDED_ID(0x35603), 0x1FFFFFCF);
if (status != ARM_DRIVER_OK) ... // error handling

Example: accept any message in object #4 regardless of the ID.

status = ptrCAN->ObjectSetFilter (4, ARM_CAN_FILTER_ID_MASKABLE_ADD, ARM_CAN_EXTENDED_ID(0), 0);
if (status != ARM_DRIVER_OK) ... // error handling

Remote Frame

In general, data transmission is performed on an autonomous basis with the data source node sending out Data Frames.

However, sending a Remote Frame allows a destination node to request the data from the source node. The examples below shows the data exchange using a Remote Transmission Request (RTR).

Example for automatic Data Message response on RTR

For automatic data message response on an RTR, the object is configured with the function ARM_CAN_ObjectConfigure obj_cfg = ARM_CAN_OBJ_RX_RTR_TX_DATA.

In this case, the function ARM_CAN_MessageSend sets a data message that is transmitted when an RTR with a matching CAN ID is received. If ARM_CAN_MessageSend was not called before the RTR is received, the response is hardware dependent (either last data message is repeated or no data message is sent until ARM_CAN_MessageSend is called).

After data transmission is completed, the driver calls a callback function ARM_CAN_SignalObjectEvent with event = ARM_CAN_EVENT_SEND_COMPLETE and the related obj_idx.

Example:

status = ptrCAN->ObjectSetFilter(0, ARM_CAN_FILTER_ID_EXACT_ADD, ARM_CAN_EXTENDED_ID(0x12345678U), 0U);
if (status != ARM_DRIVER_OK) ... // error handling
status = trCAN->ObjectConfigure(0, ARM_CAN_OBJ_RX_RTR_TX_DATA);
if (status != ARM_DRIVER_OK) ... // error handling
memset(&tx_msg_info, 0, sizeof(ARM_CAN_MSG_INFO)); // Clear transmit message structure
tx_msg_info.id = ARM_CAN_EXTENDED_ID(0x12345678U); // Set ID of message
data_buf[0] = '1'; data_buf[1] = '2'; // Prepare data to transmit
data_buf[2] = '3'; data_buf[3] = '4';
data_buf[4] = '5'; data_buf[5] = '6';
data_buf[6] = '7'; data_buf[7] = '8';
ptrCAN->MessageSend(0, &tx_msg_info, data_buf, 8); // Start send message that will be triggered on RTR reception

Example for automatic Data Message reception using RTR

For automatic data message reception on an RTR, the object is configured with the function ARM_CAN_ObjectConfigure obj_cfg = ARM_CAN_OBJ_TX_RTR_RX_DATA.

The receiver or consumer requests data with transmission of an RTR with the ARM_CAN_MessageSend. This RTR requests from the transmitter or producer to send the data message. Once the data message is received, the driver calls a callback function ARM_CAN_SignalObjectEvent with event = ARM_CAN_EVENT_RECEIVE and the related obj_idx. The received data message can then be read with the function ARM_CAN_MessageRead.

Example:

status = ptrCAN->ObjectSetFilter(0, ARM_CAN_FILTER_ID_EXACT_ADD, ARM_CAN_EXTENDED_ID(0x12345678U), 0U);
if (status != ARM_DRIVER_OK) ... // error handling
status = ptrCAN->ObjectConfigure(0, ARM_CAN_OBJ_TX_RTR_RX_DATA);
if (status != ARM_DRIVER_OK) ... // error handling
memset(&tx_msg_info, 0, sizeof(ARM_CAN_MSG_INFO)); // Clear transmit message structure
tx_msg_info.id = ARM_CAN_EXTENDED_ID(0x12345678U); // Set ID of message
tx_msg_info.rtr = 1; // Set RTR flag of message to send RTR
tx_msg_info.dlc = 1; // Set data length code of message to 1 to request 1 data byte
ptrCAN->MesageSend(0, &tx_msg_info, 0, 0); // Send RTR
// Wait for ARM_CAN_EVENT_RECEIVE
ptrCAN->MessageRead(0, &rx_msg_info, data_buf, 8); // Read received message

Data Structure Documentation

struct ARM_DRIVER_CAN

Access structure of the CAN Driver.

The functions of the CAN are accessed by function pointers exposed by this structure. Refer to Common Driver Functions for overview information.

Each instance of a CAN provides such an access structure. The instance is identified by a postfix number in the symbol name of the access structure, for example:

  • Driver_CAN0 is the name of the access struct of the first instance (no. 0).
  • Driver_CAN1 is the name of the access struct of the second instance (no. 1).

A configuration setting in the middleware allows you to connect the middleware to a specific driver instance Driver_CANn.

Data Fields

ARM_DRIVER_VERSION(* GetVersion )(void)
 Pointer to ARM_CAN_GetVersion : Get driver version.
 
ARM_CAN_CAPABILITIES(* GetCapabilities )(void)
 Pointer to ARM_CAN_GetCapabilities : Get driver capabilities.
 
int32_t(* Initialize )(ARM_CAN_SignalUnitEvent_t cb_unit_event, ARM_CAN_SignalObjectEvent_t cb_object_event)
 Pointer to ARM_CAN_Initialize : Initialize CAN interface.
 
int32_t(* Uninitialize )(void)
 Pointer to ARM_CAN_Uninitialize : De-initialize CAN interface.
 
int32_t(* PowerControl )(ARM_POWER_STATE state)
 Pointer to ARM_CAN_PowerControl : Control CAN interface power.
 
uint32_t(* GetClock )(void)
 Pointer to ARM_CAN_GetClock : Retrieve CAN base clock frequency.
 
int32_t(* SetBitrate )(ARM_CAN_BITRATE_SELECT select, uint32_t bitrate, uint32_t bit_segments)
 Pointer to ARM_CAN_SetBitrate : Set bitrate for CAN interface.
 
int32_t(* SetMode )(ARM_CAN_MODE mode)
 Pointer to ARM_CAN_SetMode : Set operating mode for CAN interface.
 
ARM_CAN_OBJ_CAPABILITIES(* ObjectGetCapabilities )(uint32_t obj_idx)
 Pointer to ARM_CAN_ObjectGetCapabilities : Retrieve capabilities of an object.
 
int32_t(* ObjectSetFilter )(uint32_t obj_idx, ARM_CAN_FILTER_OPERATION operation, uint32_t id, uint32_t arg)
 Pointer to ARM_CAN_ObjectSetFilter : Add or remove filter for message reception.
 
int32_t(* ObjectConfigure )(uint32_t obj_idx, ARM_CAN_OBJ_CONFIG obj_cfg)
 Pointer to ARM_CAN_ObjectConfigure : Configure object.
 
int32_t(* MessageSend )(uint32_t obj_idx, ARM_CAN_MSG_INFO *msg_info, const uint8_t *data, uint8_t size)
 Pointer to ARM_CAN_MessageSend : Send message on CAN bus.
 
int32_t(* MessageRead )(uint32_t obj_idx, ARM_CAN_MSG_INFO *msg_info, uint8_t *data, uint8_t size)
 Pointer to ARM_CAN_MessageRead : Read message received on CAN bus.
 
int32_t(* Control )(uint32_t control, uint32_t arg)
 Pointer to ARM_CAN_Control : Control CAN interface.
 
ARM_CAN_STATUS(* GetStatus )(void)
 Pointer to ARM_CAN_GetStatus : Get CAN status.
 

Field Documentation

ARM_DRIVER_VERSION(* GetVersion)(void)

Pointer to ARM_CAN_GetVersion : Get driver version.

ARM_CAN_CAPABILITIES(* GetCapabilities)(void)

Pointer to ARM_CAN_GetCapabilities : Get driver capabilities.

int32_t(* Initialize)(ARM_CAN_SignalUnitEvent_t cb_unit_event, ARM_CAN_SignalObjectEvent_t cb_object_event)

Pointer to ARM_CAN_Initialize : Initialize CAN interface.

int32_t(* Uninitialize)(void)

Pointer to ARM_CAN_Uninitialize : De-initialize CAN interface.

int32_t(* PowerControl)(ARM_POWER_STATE state)

Pointer to ARM_CAN_PowerControl : Control CAN interface power.

uint32_t(* GetClock)(void)

Pointer to ARM_CAN_GetClock : Retrieve CAN base clock frequency.

int32_t(* SetBitrate)(ARM_CAN_BITRATE_SELECT select, uint32_t bitrate, uint32_t bit_segments)

Pointer to ARM_CAN_SetBitrate : Set bitrate for CAN interface.

int32_t(* SetMode)(ARM_CAN_MODE mode)

Pointer to ARM_CAN_SetMode : Set operating mode for CAN interface.

ARM_CAN_OBJ_CAPABILITIES(* ObjectGetCapabilities)(uint32_t obj_idx)

Pointer to ARM_CAN_ObjectGetCapabilities : Retrieve capabilities of an object.

int32_t(* ObjectSetFilter)(uint32_t obj_idx, ARM_CAN_FILTER_OPERATION operation, uint32_t id, uint32_t arg)

Pointer to ARM_CAN_ObjectSetFilter : Add or remove filter for message reception.

int32_t(* ObjectConfigure)(uint32_t obj_idx, ARM_CAN_OBJ_CONFIG obj_cfg)

Pointer to ARM_CAN_ObjectConfigure : Configure object.

int32_t(* MessageSend)(uint32_t obj_idx, ARM_CAN_MSG_INFO *msg_info, const uint8_t *data, uint8_t size)

Pointer to ARM_CAN_MessageSend : Send message on CAN bus.

int32_t(* MessageRead)(uint32_t obj_idx, ARM_CAN_MSG_INFO *msg_info, uint8_t *data, uint8_t size)

Pointer to ARM_CAN_MessageRead : Read message received on CAN bus.

int32_t(* Control)(uint32_t control, uint32_t arg)

Pointer to ARM_CAN_Control : Control CAN interface.

ARM_CAN_STATUS(* GetStatus)(void)

Pointer to ARM_CAN_GetStatus : Get CAN status.

struct ARM_CAN_CAPABILITIES

CAN Device Driver Capabilities.

A CAN driver can be implemented with different capabilities encoded in the data fields of this structure.

Returned by:

See Also
ARM_CAN_OBJ_CAPABILITIES for information about CAN objects.
Data Fields
uint32_t num_objects: 8 Number of CAN Message Objects available.
uint32_t reentrant_operation: 1 Support for reentrant calls to ARM_CAN_MessageSend, ARM_CAN_MessageRead, ARM_CAN_ObjectConfigure and abort message sending used by ARM_CAN_Control.
uint32_t fd_mode: 1 Support for CAN with flexible data-rate mode (CAN_FD) (set by ARM_CAN_Control)
uint32_t restricted_mode: 1 Support for restricted operation mode (set by ARM_CAN_SetMode)
uint32_t monitor_mode: 1 Support for bus monitoring mode (set by ARM_CAN_SetMode)
uint32_t internal_loopback: 1 Support for internal loopback mode (set by ARM_CAN_SetMode)
uint32_t external_loopback: 1 Support for external loopback mode (set by ARM_CAN_SetMode)
uint32_t reserved: 18 Reserved (must be zero)
struct ARM_CAN_STATUS

CAN Status.

Structure with information about the status of the CAN unit state and errors. The data fields encode the unit bus state, last error code, transmitter error count, and receiver error count.

Returned by:

Data Fields
uint32_t unit_state: 4 Unit bus state.
uint32_t last_error_code: 4 Last error code.
uint32_t tx_error_count: 8 Transmitter error count.
uint32_t rx_error_count: 8 Receiver error count.
uint32_t reserved: 8
struct ARM_CAN_MSG_INFO

CAN Message Information.

Structure with information about the CAN message.

In CAN mode, the following ARM_CAN_MSG_INFO data fields are ignored: edl, brs, esi.
In CAN FD mode, the following ARM_CAN_MSG_INFO data field is ignored: rtr.

Parameter for:

See Also
CAN Message Filtering
Remote Frame
Data Fields
uint32_t id CAN identifier with frame format specifier (bit 31)
uint32_t rtr: 1 Remote transmission request frame.
uint32_t edl: 1 Flexible data-rate format extended data length.
uint32_t brs: 1 Flexible data-rate format with bitrate switch.
uint32_t esi: 1 Flexible data-rate format error state indicator.
uint32_t dlc: 4 Data length code.
uint32_t reserved: 24
struct ARM_CAN_OBJ_CAPABILITIES

CAN Object Capabilities.

A CAN object can be implemented with different capabilities encoded in the data fields of this structure.

Returned by:

See Also
ARM_CAN_ObjectConfigure
ARM_CAN_MessageSend
ARM_CAN_MessageRead
ARM_CAN_MSG_INFO
CAN Message Filtering
Data Fields
uint32_t tx: 1 Object supports transmission.
uint32_t rx: 1 Object supports reception.
uint32_t rx_rtr_tx_data: 1 Object supports RTR reception and automatic Data Frame transmission.
uint32_t tx_rtr_rx_data: 1 Object supports RTR transmission and automatic Data Frame reception.
uint32_t multiple_filters: 1 Object allows assignment of multiple filters to it.
uint32_t exact_filtering: 1 Object supports exact identifier filtering.
uint32_t range_filtering: 1 Object supports range identifier filtering.
uint32_t mask_filtering: 1 Object supports mask identifier filtering.
uint32_t message_depth: 8 Number of messages buffers (FIFO) for that object.
uint32_t reserved: 16 Reserved (must be zero)

Typedef Documentation

ARM_CAN_SignalUnitEvent_t

Pointer to ARM_CAN_SignalUnitEvent : Signal CAN Unit Event.

Provides the typedef for the callback function ARM_CAN_SignalUnitEvent.

Parameter for:

ARM_CAN_SignalObjectEvent_t

Pointer to ARM_CAN_SignalObjectEvent : Signal CAN Object Event.

Provides the typedef for the callback function ARM_CAN_SignalObjectEvent.

Parameter for:

Function Documentation

ARM_DRIVER_VERSION ARM_CAN_GetVersion ( void  )

Get driver version.

Returns
ARM_DRIVER_VERSION

The function ARM_CAN_GetVersion returns version information of the driver implementation in ARM_DRIVER_VERSION

  • API version is the version of the CMSIS-Driver specification used to implement this driver.
  • Driver version is source code version of the actual driver implementation.

Example:

extern ARM_DRIVER_CAN Driver_CAN0;
ARM_DRIVER_CAN *drv_info;
void setup_can (void) {
drv_info = &Driver_CAN0;
version = drv_info->GetVersion ();
if (version.api < 0x10A) { // requires at minimum API version 1.10 or higher
// error handling
return;
}
}
ARM_CAN_CAPABILITIES ARM_CAN_GetCapabilities ( void  )

Get driver capabilities.

Returns
ARM_CAN_CAPABILITIES

The function ARM_CAN_GetCapabilities returns information about the capabilities in this driver implementation. The data fields of the structure ARM_CAN_CAPABILITIES encode various capabilities.

Example:

extern ARM_DRIVER_CAN Driver_CAN0;
ARM_DRIVER_CAN *drv_info;
void read_capabilities (void) {
ARM_CAN_CAPABILITIES drv_capabilities;
drv_info = &Driver_CAN0;
drv_capabilities = drv_info->GetCapabilities ();
// interrogate capabilities
}
int32_t ARM_CAN_Initialize ( ARM_CAN_SignalUnitEvent_t  cb_unit_event,
ARM_CAN_SignalObjectEvent_t  cb_object_event 
)

Initialize CAN interface and register signal (callback) functions.

Parameters
[in]cb_unit_eventPointer to ARM_CAN_SignalUnitEvent callback function
[in]cb_object_eventPointer to ARM_CAN_SignalObjectEvent callback function
Returns
Status Error Codes

The function initializes the CAN interface.

The function performs the following operations:

  • Initializes the resources needed for the CAN interface, for example dynamic memory allocation, RTOS object allocation, and possibly hardware pin configuration.
  • Registers the ARM_CAN_SignalUnitEvent callback function.
  • Registers the ARM_CAN_SignalObjectEvent callback function.

The parameter cb_unit_event is a pointer to the ARM_CAN_SignalUnitEvent callback function; use a NULL pointer when no callback signals are required.

The parameter cb_object_event is a pointer to the ARM_CAN_SignalObjectEvent callback function; use a NULL pointer when no callback signals are required.

Example:

int32_t ARM_CAN_Uninitialize ( void  )

De-initialize CAN interface.

Returns
Status Error Codes

The function ARM_CAN_Uninitialize de-initializes the resources of the CAN interface. It is called to release the software resources used by the interface such as deallocate any RTOS objects, dynamic memory and pin de-configuration.

int32_t ARM_CAN_PowerControl ( ARM_POWER_STATE  state)

Control CAN interface power.

Parameters
[in]statePower state
  • ARM_POWER_OFF : power off: no operation possible
  • ARM_POWER_LOW : low power mode: retain state, detect and signal wake-up events
  • ARM_POWER_FULL : power on: full operation at maximum performance
Returns
Status Error Codes

The function ARM_CAN_PowerControl controls the power modes of the CAN interface.

The parameter state can be:

  • ARM_POWER_FULL: Activate clocks and driver functionality as if peripheral was reset.
  • ARM_POWER_OFF: Unconditionally put peripheral into non-functional (reset) state.
  • ARM_POWER_LOW: Put peripheral into low power consumption state ready to wake up on bus event.
uint32_t ARM_CAN_GetClock ( void  )

Retrieve CAN base clock frequency.

Returns
base clock frequency

The function ARM_CAN_GetClock returns the CAN base clock frequency in [Hz]. This value may be used to validate the bitrate for the function ARM_CAN_SetBitrate.

Example:

CAN_clock = ARM_CAN_GetClock(); // CAN base clock frequency
int32_t ARM_CAN_SetBitrate ( ARM_CAN_BITRATE_SELECT  select,
uint32_t  bitrate,
uint32_t  bit_segments 
)

Set bitrate for CAN interface.

Parameters
[in]selectBitrate selection
  • ARM_CAN_BITRATE_NOMINAL : nominal (flexible data-rate arbitration) bitrate
  • ARM_CAN_BITRATE_FD_DATA : flexible data-rate data bitrate
[in]bitrateBitrate
[in]bit_segmentsBit segments settings
Returns
Status Error Codes

The function ARM_CAN_SetBitrate sets the CAN communication bit rate.

The parameter select selects the bit rate affected by function call as defined in ARM_CAN_BITRATE_SELECT and listed in the table below.

Parameter select CAN Mode Bit Rate
ARM_CAN_BITRATE_NOMINAL Select nominal (flexible data-rate arbitration) bitrate (CAN 2.0B)
ARM_CAN_BITRATE_FD_DATA Select flexible data-rate data bitrate (CAN_FD)

The parameter bitrate is the bit rate for the selected CAN mode.

The parameter bit_segments is used to setup the time quanta for sampling (see picture below). The values listed in the table below are ORed and specify the various sampling segments. The CAN controller samples each bit on the bus at the Sample Point.

Parameter bit_segments Bit for select = ARM_CAN_BITRATE_NOMINAL
(CAN specification)
for select = ARM_CAN_BITRATE_NOMINAL
(CAN FD specification)
for select = ARM_CAN_BITRATE_FD_DATA
(CAN FD specification)
ARM_CAN_BIT_PROP_SEG(x)
Propagation Time Segment
(PROP_SEG)
0..7 x = [1..8] x = [1..32] or more x = [0..8]
ARM_CAN_BIT_PHASE_SEG1(x)
Phase Buffer Segment 1
(PHASE_SEG1)
8..15 x = [1..8] x = [1..32] or more x = [1..8]
ARM_CAN_BIT_PHASE_SEG2(x)
Phase Buffer Segment 2
(PHASE_SEG2)
16..23 x = [1..8] x = [1..32] or more x = [1..8]
The maximum allowed value is x = MAX (PHASE_SEG1, IPT). IPT = Information Processing Time. Usually, IPT = 2. Exceptions apply. Read the specifications of your CAN controller.
ARM_CAN_BIT_SJW(x)
(Re-)Synchronization Jump Width
(SJW).
24..31 x = [1..4] x = [1..4] x = [1..4]
The maximum allowed value is x = MIN (MIN (PHASE_SEG1, PHASE_SEG2), 4). SJW is not allowed to be greater than either PHASE segment.

The picture shows a Nominal Bit Time with 10 time quanta.

CAN_Bit_Timing.png
CAN Bit Timing

The time quanta (N) per bit is:

N = 1 + PROP_SEG + PHASE_SEG1 + PHASE_SEG2; // note SYNC_SEG is always 1

The driver uses this value and the CAN clock to calculate a suitable prescaler value (P). If the driver cannot achieve the requested bitrate it returns with ARM_CAN_INVALID_BITRATE. The formula for the bitrate is:

bitrate = (CAN_Clock / P) / N;

Example:

status = ptrCAN->SetBitrate (ARM_CAN_BITRATE_NOMINAL, // Set nominal bitrate
125000U, // Set bitrate to 125 kbit/s
ARM_CAN_BIT_PROP_SEG(5U) | // Set propagation segment to 5 time quanta
ARM_CAN_BIT_PHASE_SEG1(1U) | // Set phase segment 1 to 1 time quantum (sample point at 87.5% of bit time)
ARM_CAN_BIT_PHASE_SEG2(1U) | // Set phase segment 2 to 1 time quantum (total bit is 8 time quanta long)
ARM_CAN_BIT_SJW(1U)); // Resynchronization jump width is same as phase segment 2

In this example, N = 8 and with a CAN_Clock = 8MHz the prescaler (P) is calculated by the driver to 8.

int32_t ARM_CAN_SetMode ( ARM_CAN_MODE  mode)

Set operating mode for CAN interface.

Parameters
[in]modeOperating mode
  • ARM_CAN_MODE_INITIALIZATION : initialization mode
  • ARM_CAN_MODE_NORMAL : normal operation mode
  • ARM_CAN_MODE_RESTRICTED : restricted operation mode
  • ARM_CAN_MODE_MONITOR : bus monitoring mode
  • ARM_CAN_MODE_LOOPBACK_INTERNAL : loopback internal mode
  • ARM_CAN_MODE_LOOPBACK_EXTERNAL : loopback external mode
Returns
Status Error Codes

The function ARM_CAN_SetMode sets the CAN bus communication mode using the parameter mode.

The table lists the values for mode.

Parameter mode Bus Communication Mode supported when ARM_CAN_OBJ_CAPABILITIES data field
ARM_CAN_MODE_INITIALIZATION Initialization mode; Used to setup communication parameters for the reception objects and global filtering, while peripheral is not active on the bus. Refer to CAN Message Filtering for details. always supported
ARM_CAN_MODE_NORMAL Normal operation mode. Used when peripheral is in active mode to receive, transmit, and acknowledge messages on the bus. Depending on the current unit state, it can generate error or overload messages. Verify the unit state with ARM_CAN_GetStatus. always supported
ARM_CAN_MODE_RESTRICTED Restricted operation mode. Used for monitoring the bus communication non-intrusively without transmitting. restricted_mode = 1
ARM_CAN_MODE_MONITOR Bus monitoring mode. monitor_mode = 1
ARM_CAN_MODE_LOOPBACK_INTERNAL Test mode; loopback of CAN transmission to its receiver. No transmission visible on CAN bus. internal_loopback = 1
ARM_CAN_MODE_LOOPBACK_EXTERNAL Test mode; loopback of CAN transmission to its receiver. Transmission is visible on CAN bus. external_loopback = 1
ARM_CAN_OBJ_CAPABILITIES ARM_CAN_ObjectGetCapabilities ( uint32_t  obj_idx)

Retrieve capabilities of an object.

Parameters
[in]obj_idxObject index
Returns
ARM_CAN_OBJ_CAPABILITIES

The function ARM_CAN_ObjectGetCapabilities retrieves the capabilities of a CAN object. The structure ARM_CAN_OBJ_CAPABILITIES stores the values.

The parameter obj_idx is the message object index.

See Also
ARM_CAN_ObjectConfigure
ARM_CAN_ObjectSetFilter
int32_t ARM_CAN_ObjectSetFilter ( uint32_t  obj_idx,
ARM_CAN_FILTER_OPERATION  operation,
uint32_t  id,
uint32_t  arg 
)

Add or remove filter for message reception.

Parameters
[in]obj_idxObject index of object that filter should be or is assigned to
[in]operationOperation on filter
  • ARM_CAN_FILTER_ID_EXACT_ADD : add exact id filter
  • ARM_CAN_FILTER_ID_EXACT_REMOVE : remove exact id filter
  • ARM_CAN_FILTER_ID_RANGE_ADD : add range id filter
  • ARM_CAN_FILTER_ID_RANGE_REMOVE : remove range id filter
  • ARM_CAN_FILTER_ID_MASKABLE_ADD : add maskable id filter
  • ARM_CAN_FILTER_ID_MASKABLE_REMOVE : remove maskable id filter
[in]idID or start of ID range (depending on filter type)
[in]argMask or end of ID range (depending on filter type)
Returns
Status Error Codes

The function ARM_CAN_ObjectSetFilter sets or removes the filter for message reception. Refer to CAN Message Filtering for details on filtering.

The parameter obj_idx is the message object index.
The parameter operation is the operation on the filter as listed in the table below and which are defined in the structure ARM_CAN_FILTER_OPERATION.

Parameter operation Operation on Filter supported when ARM_CAN_OBJ_CAPABILITIES data field
ARM_CAN_FILTER_ID_EXACT_ADD Add exact ID filter exact_filtering = 1
ARM_CAN_FILTER_ID_EXACT_REMOVE Remove exact ID filter exact_filtering = 1
ARM_CAN_FILTER_ID_RANGE_ADD Add range ID filter range_filtering = 1
ARM_CAN_FILTER_ID_RANGE_REMOVE Remove range ID filter range_filtering = 1
ARM_CAN_FILTER_ID_MASKABLE_ADD Add maskable ID filter mask_filtering = 1
ARM_CAN_FILTER_ID_MASKABLE_REMOVE Remove maskable ID filter mask_filtering = 1

The parameter id is the identifier of the filter or defines the start of the filter range (depends on the filter operation).
The parameter arg is the mask of the filter or defines the end of the filter range (depends on the filter operation).

See Also
ARM_CAN_ObjectConfigure
int32_t ARM_CAN_ObjectConfigure ( uint32_t  obj_idx,
ARM_CAN_OBJ_CONFIG  obj_cfg 
)

Configure object.

Parameters
[in]obj_idxObject index
[in]obj_cfgObject configuration state
  • ARM_CAN_OBJ_INACTIVE : deactivate object
  • ARM_CAN_OBJ_RX : configure object for reception
  • ARM_CAN_OBJ_TX : configure object for transmission
  • ARM_CAN_OBJ_RX_RTR_TX_DATA : configure object that on RTR reception automatically transmits Data Frame
  • ARM_CAN_OBJ_TX_RTR_RX_DATA : configure object that transmits RTR and automatically receives Data Frame
Returns
Status Error Codes

The function ARM_CAN_ObjectConfigure configures the message object, which can be a mailbox or FIFO. Refer to CAN Message Filtering for details.

The parameter obj_idx specifies the message object index.
The parameter obj_cfg configures the object with values as shown in the following table.

Parameter obj_cfg Object Configuration supported when ARM_CAN_OBJ_CAPABILITIES data field
ARM_CAN_OBJ_INACTIVE Deactivate object (default after ARM_CAN_Initialize) always supported
ARM_CAN_OBJ_RX Receive object; read received message with ARM_CAN_MessageRead. rx = 1
ARM_CAN_OBJ_TX Transmit object; send message with ARM_CAN_MessageSend. tx = 1
ARM_CAN_OBJ_RX_RTR_TX_DATA Remote Frame Receive; when RTR is received data message is transmitted; set data message with ARM_CAN_MessageSend. rx_rtr_tx_data = 1
ARM_CAN_OBJ_TX_RTR_RX_DATA Remote Frame Transmit; a RTR is sent with ARM_CAN_MessageSend to trigger object reception; read received data message with ARM_CAN_MessageRead. tx_rtr_rx_data = 1

When the object is deactivated, it is not used for data communication.

See Also
ARM_CAN_ObjectSetFilter
int32_t ARM_CAN_MessageSend ( uint32_t  obj_idx,
ARM_CAN_MSG_INFO msg_info,
const uint8_t *  data,
uint8_t  size 
)

Send message on CAN bus.

Parameters
[in]obj_idxObject index
[in]msg_infoPointer to CAN message information
[in]dataPointer to data buffer
[in]sizeNumber of data bytes to send
Returns
value >= 0 number of data bytes accepted to send
value < 0 Status Error Codes

The function ARM_CAN_MessageSend sends a CAN message on the CAN bus, or sets data message that will be automatically returned upon RTR reception with matching CAN ID.

Only one message can be sent with a call to this function (for CAN up to 8 bytes; for CAN FD up to 64 bytes of data). A message transmission can be terminated with a call to the function ARM_CAN_Control with control = ARM_CAN_ABORT_MESSAGE_SEND.

The parameter obj_idx specifies the message object index.

The parameter msg_info is a pointer to the structure ARM_CAN_MSG_INFO, which contains the following relevant data fields for sending message:

  • id: Identifier of the message; bit 31 specifies if this is an 11-bit or 29-bit identifier.
  • rtr: Specifies if Remote Transmission Request should be sent (dlc is used for number of requested bytes), otherwise the data message will be sent. Refer to Remote Frame for details.
  • edl: Specifies if Extended Data Length is used; for CAN FD, message can contain up to 64 data bytes.
  • brs: Specifies if Bit Rate Switching is to be used; for CAN FD, the bit rate can be increased during data phase.
  • dlc: Data Length Code of requested data bytes when sending Remote Transmission Request.

The parameter data is a pointer to the data buffer.
The parameter size is the number of data bytes to send.
The function returns the number of bytes accepted to be sent or ARM_DRIVER_ERROR_BUSY if the hardware is not ready to accept a new message for transmission.

When the message is sent, the callback function ARM_CAN_SignalObjectEvent is called signalling ARM_CAN_EVENT_SEND_COMPLETE on specified object.

See Also
CAN Message Filtering

Example:

status = ptrCAN->ObjectConfigure(0, ARM_CAN_OBJ_TX);
if (status != ARM_DRIVER_OK ) { Error_Handler(); }
memset(&tx_msg_info, 0, sizeof(ARM_CAN_MSG_INFO)); // Clear transmit message structure
tx_msg_info.id = ARM_CAN_EXTENDED_ID(0x12345678U); // Set ID of message
data_buf[0] = '1'; data_buf[1] = '2'; // Prepare data to transmit
data_buf[2] = '3'; data_buf[3] = '4';
data_buf[4] = '5'; data_buf[5] = '6';
data_buf[6] = '7'; data_buf[7] = '8';
status = ptrCAN->MesageSend(0, &tx_msg_info, data_buf, 8); // Send message
if (status != ARM_DRIVER_OK ) { Error_Handler(); }
int32_t ARM_CAN_MessageRead ( uint32_t  obj_idx,
ARM_CAN_MSG_INFO msg_info,
uint8_t *  data,
uint8_t  size 
)

Read message received on CAN bus.

Parameters
[in]obj_idxObject index
[out]msg_infoPointer to read CAN message information
[out]dataPointer to data buffer for read data
[in]sizeMaximum number of data bytes to read
Returns
value >= 0 number of data bytes read
value < 0 Status Error Codes

The function ARM_CAN_MessageRead reads the message received on the CAN bus, if obj_idx was configured for reception or for automatic Data Message reception using RTR and the callback function ARM_CAN_SignalObjectEvent was called signalling ARM_CAN_EVENT_RECEIVE. If the message was overrun by another received message, then the callback function ARM_CAN_SignalObjectEvent will be called signalling ARM_CAN_EVENT_RECEIVE_OVERRUN.

The function can read a maximum of 8 data bytes for CAN and 64 bytes for CAN FD.

The parameter obj_idx specifies the message object index.
The parameter msg_info is a pointer to the CAN information structure.
The parameter data is a pointer to the data buffer for reading data.
The parameter size is data buffer size in bytes and indicates the maximum number of bytes that can be read.

The function returns the number of read data in bytes or the Status Error Codes.

All data fields of the structure ARM_CAN_MSG_INFO are updated as described below:

  • id: Identifier of the message that was received, bit 31 specifies if it is a 11-bit identifier or 29-bit identifier.
  • rtr: 1 = Remote Frame Request was received (dlc is number of requested bytes). 0 = data message
  • edl: 1 = CAN FD Extended Data Length message was received. 0 = not Extended Data Length message.
  • brs: 1 = CAN FD Bit Rate Switching was used for message transfer. 0 = no Bit Rate Switching was used.
  • esi: 1 = CAN FD Error State Indicator is active for received message. 0 = Error State Indicator is not active.
  • dlc: Data Length Code is the number of data bytes in the received message or number of data bytes requested by RTR.

Message reception can be disabled by de-configuring the receive object with the function ARM_CAN_ObjectConfigure.

int32_t ARM_CAN_Control ( uint32_t  control,
uint32_t  arg 
)

Control CAN interface.

Parameters
[in]controlOperation
[in]argArgument of operation
Returns
Status Error Codes

The function ARM_CAN_Control controls the CAN interface settings and executes various operations.

The parameter control specifies various operations that are listed in the table below.

The parameters arg provides, depending on the control value, additional information or set values.

Parameter control Operation
ARM_CAN_SET_FD_MODE Select CAN FD mode; arg : 0 = CAN 2.0B; 1 = CAN FD.
ARM_CAN_ABORT_MESSAGE_SEND Abort sending of CAN message; arg : object index
ARM_CAN_CONTROL_RETRANSMISSION Enable/disable automatic retransmission; arg : 0 = disable, 1 = enable (default state)
ARM_CAN_SET_TRANSCEIVER_DELAY Set transceiver delay; arg : delay in time quanta

Verify the CAN interface capabilities with ARM_CAN_GetCapabilities.

ARM_CAN_STATUS ARM_CAN_GetStatus ( void  )

Get CAN status.

Returns
CAN status ARM_CAN_STATUS

The function ARM_CAN_GetStatus retrieves runtime information on CAN bus and CAN unit state.

The following defines give information about the current unit involvement in bus communication:

Unit State Description
ARM_CAN_UNIT_STATE_INACTIVE Unit state: Not active on the bus. Unit is in initialization state.
ARM_CAN_UNIT_STATE_ACTIVE Unit state: Active on the bus. Unit can generate active error frames.
ARM_CAN_UNIT_STATE_PASSIVE Unit state: Error passive. Unit is interacting on the bus but does not send active error frames.
ARM_CAN_UNIT_STATE_BUS_OFF Unit state: Bus-off. Unit does not participate on the bus but monitors it and can recover to active state.

The following defines are error codes of the last error that happened on the bus:

Last Error Code Description
ARM_CAN_LEC_NO_ERROR No error. There was no error since last read of status or last successful transmit or receive.
ARM_CAN_LEC_BIT_ERROR Bit error. The bit monitored is different than the bit sent (except during arbitration phase).
ARM_CAN_LEC_STUFF_ERROR Bit stuffing error. There were 6 consecutive same bit levels on the bus.
ARM_CAN_LEC_CRC_ERROR CRC error. CRC of received data is not as expected.
ARM_CAN_LEC_FORM_ERROR Illegal fixed-form bit. Error in fixed form bits.
ARM_CAN_LEC_ACK_ERROR Acknowledgment error. Message was not acknowledged by any receiver on the bus.
void ARM_CAN_SignalUnitEvent ( uint32_t  event)

Signal CAN unit event.

Parameters
[in]eventCAN Unit Events
Returns
none

The function ARM_CAN_SignalUnitEvent is a callback function registered by the function ARM_CAN_Initialize.

The parameter event indicates unit event that occurred during driver operation.

The following callback notifications are generated:

Parameter event Value Description
ARM_CAN_EVENT_UNIT_INACTIVE 0 Unit entered Inactive state.
ARM_CAN_EVENT_UNIT_ACTIVE 1 Unit entered Error Active state.
ARM_CAN_EVENT_UNIT_WARNING 2 Unit entered Error Warning state (one or both error counters >= 96).
ARM_CAN_EVENT_UNIT_PASSIVE 3 Unit entered Error Passive state.
ARM_CAN_EVENT_UNIT_BUS_OFF 4 Unit entered Bus-off state.
See Also
ARM_CAN_GetStatus
void ARM_CAN_SignalObjectEvent ( uint32_t  obj_idx,
uint32_t  event 
)

Signal CAN object event.

Parameters
[in]obj_idxObject index
[in]eventCAN Object Events
Returns
none

The function ARM_CAN_SignalObjectEvent is a callback function registered by the function ARM_CAN_Initialize and signals a CAN message object event.

The parameter obj_idx is the index of the message object.
The parameter event indicates object event that occurred during driver operation.

The following events can be generated:

Parameter event Bit Description
ARM_CAN_EVENT_SEND_COMPLETE 0 Message was sent successfully by the obj_idx object.
ARM_CAN_EVENT_RECEIVE 1 Message was received successfully by the obj_idx object.
ARM_CAN_EVENT_RECEIVE_OVERRUN 2 Message was overwritten before it was read on the obj_idx object.
See Also
ARM_CAN_MessageSend
ARM_CAN_MessageRead
ARM_CAN_ObjectConfigure