The section describes the programming interface of the FlexCAN Peripheral driver. More...

Data Structures
struct	flexcan_bitrate_table_t
	FlexCAN bit rate and the related timing segments structure. More...

struct	flexcan_data_info_t
	FlexCAN data info from user. More...

Macros
#define	FSL_CAN_INTERRUPT_COUNT (4)

Enumerations
enum	flexcan_bitrate_t { kFlexCanBitrate_125k = 125000, kFlexCanBitrate_250k = 250000, kFlexCanBitrate_500k = 500000, kFlexCanBitrate_750k = 750000, kFlexCanBitrate_1M = 1000000 }
	FlexCAN bitrates supported. More...

Bit rate
flexcan_status_t	flexcan_set_bitrate (uint8_t instance, flexcan_bitrate_t bitrate)
	Sets FlexCAN bit rate. More...

flexcan_status_t	flexcan_get_bitrate (uint8_t instance, flexcan_bitrate_t *bitrate)
	Gets FlexCAN bit rate. More...

Global mask
void	flexcan_set_mask_type (uint8_t instance, flexcan_rx_mask_type_t type)
	Sets the RX masking type. More...

flexcan_status_t	flexcan_set_rx_fifo_global_mask (uint8_t instance, flexcan_mb_id_type_t id_type, uint32_t mask)
	Sets the FlexCAN RX FIFO global standard or extended mask. More...

flexcan_status_t	flexcan_set_rx_mb_global_mask (uint8_t instance, flexcan_mb_id_type_t id_type, uint32_t mask)
	Sets the FlexCAN RX MB global standard or extended mask. More...

flexcan_status_t	flexcan_set_rx_individual_mask (uint8_t instance, const flexcan_user_config_t *data, flexcan_mb_id_type_t id_type, uint32_t mb_idx, uint32_t mask)
	Sets the FlexCAN RX individual standard or extended mask. More...

Init and Shutdown
flexcan_status_t	flexcan_init (uint8_t instance, const flexcan_user_config_t *data, bool enable_err_interrupts)
	Initializes the FlexCAN peripheral. More...

uint32_t	flexcan_shutdown (uint8_t instance)
	Shut down a FlexCAN instance. More...

Send configuration
flexcan_status_t	flexcan_tx_mb_config (uint8_t instance, const flexcan_user_config_t data, uint32_t mb_idx, flexcan_data_info_t tx_info, uint32_t msg_id)
	FlexCAN transmit message buffer field configuration. More...

flexcan_status_t	flexcan_send (uint8_t instance, const flexcan_user_config_t data, uint32_t mb_idx, flexcan_data_info_t tx_info, uint32_t msg_id, uint32_t num_bytes, uint8_t *mb_data)
	Sends FlexCAN messages. More...

Receive configuration
flexcan_status_t	flexcan_rx_mb_config (uint8_t instance, const flexcan_user_config_t data, uint32_t mb_idx, flexcan_data_info_t rx_info, uint32_t msg_id)
	FlexCAN receive message buffer field configuration. More...

flexcan_status_t	flexcan_rx_fifo_config (uint8_t instance, const flexcan_user_config_t data, flexcan_rx_fifo_id_element_format_t id_format, flexcan_id_table_t id_filter_table)
	FlexCAN RX FIFO field configuration. More...

flexcan_status_t	flexcan_start_receive (uint8_t instance, const flexcan_user_config_t data, uint32_t mb_idx, uint32_t receiveDataCount, bool is_rx_mb_data, bool is_rx_fifo_data, flexcan_mb_t rx_mb, flexcan_mb_t *rx_fifo)
	FlexCAN is waiting to receive data. More...

flexcan_status_t	flexcan_receive (uint8_t instance, const flexcan_user_config_t data, uint32_t mb_idx, flexcan_data_info_t rx_info, uint32_t msg_id, flexcan_rx_fifo_id_element_format_t id_format, flexcan_id_table_t id_filter_table, uint32_t receiveDataCount, flexcan_mb_t rx_mb, flexcan_mb_t *rx_fifo)
	FlexCAN is preparing to receive data. More...

FlexCAN Driver

Overview

The FlexCAN (flexible controller area network) module is a communication controller implementing the CAN protocol according to the CAN 2.0B protocol specification. The FlexCAN module supports both standard and extended message frames. The Message Buffers are stored in an embedded RAM dedicated to the FlexCAN module. The CAN Protocol Engine (PE) sub-module manages the serial communication on the CAN bus by requesting RAM access for receiving and transmitting message frames, validating received messages, and performing error handling.

Initialization

To initialize the FlexCAN driver, call the flexcan_init() function and pass the instance number of the FlexCAN you want to use. For instance, to use FlexCAN0, pass a value of 0 to the flexcan_init function. In addition, you should also pass a user configuration structure #flexcan_config_t, as shown here:

// FlexCAN configuration structure for user
typedef struct FLEXCANConfig {
    uint32_t num_mb;                                
    uint32_t max_num_mb;                            
    flexcan_rx_fifo_id_filter_num_t num_id_filters; 
    bool is_rx_fifo_needed;                         
    bool is_rx_mb_needed;                           
} flexcan_config_t;

Typically, the user configures the #flexcan_config_t instantiation as 16 message buffers needed, 16 message buffers available, 8 RX FIFO ID filters, set to true when RX FIFO is needed and when RX Message Buffers are needed. The user can easily modify the #flexcan_config_t instantiation to configure the FlexCAN peripheral to a different number of message buffers, which are used with/without RX FIFO and RX MB. This is a code example to set up a FlexCAN configuration instantiation:

flexcan_config_t flexcan1_data;
flexcan1_data.num_mb = 16;
flexcan1_data.max_num_mb = 16;
flexcan1_data.num_id_filters = kFlexCanRxFifoIDFilters_8;
flexcan1_data.is_rx_fifo_needed = true;
flexcan1_data.is_rx_mb_needed = true;

Module timing

FlexCAN bit rate is derived from the serial clock, which is generated by dividing the PE clock by the programmed PRESDIV value. Each serial clock period is also called a time quantum. The FlexCAN bit-rate is defined as the Sclock divided by the number of time quanta, where time quanta are further broken down segments within the bit time (time to transmit and sample a bit). The following list shows the CAN bit-rates that are supported in the FlexCAN driver.

1 Mbytes/s
750 Kbytes/s
500 Kbytes/s
250 Kbytes/s
125 Kbytes/s

The FlexCAN module supports several different ways to set up the bit timing parameters that are required by the CAN protocol. The Control Register has various fields used to control bit timing parameters: PRESDIV, PROPSEG, PSEG1, PSEG2, and RJW.To calculate the CAN bit timing parameters, use the method outlined in AN1798, section 4.1. A maximum time for PROP_SEG is used, the remaining TQ is split equally between PSEG1 and PSEG2, provided PSEG2 >=2. RJW is set to the minimum of 4 or to the PSEG1.

Transfers

To transmit a FlexCAN frame, the CPU must prepare a message buffer for transmission by calling the flexcan_send() function. To receive the FlexCAN frames into a message buffer, the CPU must also prepare it for reception by calling the flexcan_receive() function. The FlexCAN driver implements send and receive configurations and prepares to send and receive data from TX MBs to RX MBs or/and RX FIFO. The FlexCAN uses only the interrupt-driven process to transfer data.

Data Structure Documentation

struct flexcan_bitrate_table_t

Data Fields
flexcan_bitrate_t	bit_rate
	bit rate

uint32_t	propseg
	Propagation segment.

uint32_t	pseg1
	Phase segment 1.

uint32_t	pseg2
	Phase segment 2.

uint32_t	pre_divider
	Clock pre divider.

uint32_t	rjw
	Re-sync jump width.

struct flexcan_data_info_t

Data Fields
flexcan_mb_id_type_t	msg_id_type
	Type of message ID (standard or extended)

uint32_t	data_length
	Length of Data in Bytes.

Enumeration Type Documentation

enum flexcan_bitrate_t

Enumerator
kFlexCanBitrate_125k	125 kHz
kFlexCanBitrate_250k	250 kHz
kFlexCanBitrate_500k	500 kHz
kFlexCanBitrate_750k	750 kHz
kFlexCanBitrate_1M	1 MHz

Function Documentation

flexcan_status_t flexcan_set_bitrate	(	uint8_t	instance,
		flexcan_bitrate_t	bitrate
	)

Parameters

instance	A FlexCAN instance number
bit	rate Selects a FlexCAN bit rate in the bit_rate_table.

Returns: 0 if successful; non-zero failed

flexcan_status_t flexcan_get_bitrate	(	uint8_t	instance,
		flexcan_bitrate_t *	bitrate
	)

Parameters

instance	A FlexCAN instance number
bit	rate A pointer to a variable for returning the FlexCAN bit rate in the bit_rate_table.

Returns: 0 if successful; non-zero failed

void flexcan_set_mask_type	(	uint8_t	instance,
		flexcan_rx_mask_type_t	type
	)

Parameters

instance	A FlexCAN instance number
type	The FlexCAN RX mask type

flexcan_status_t flexcan_set_rx_fifo_global_mask	(	uint8_t	instance,
		flexcan_mb_id_type_t	id_type,
		uint32_t	mask
	)

Parameters

instance	A FlexCAN instance number
id_type	Standard ID or extended ID
mask	Mask value

Returns: 0 if successful; non-zero failed

flexcan_status_t flexcan_set_rx_mb_global_mask	(	uint8_t	instance,
		flexcan_mb_id_type_t	id_type,
		uint32_t	mask
	)

Parameters

instance	A FlexCAN instance number
id_type	Standard ID or extended ID
mask	Mask value

Returns: 0 if successful; non-zero failed

flexcan_status_t flexcan_set_rx_individual_mask	(	uint8_t	instance,
		const flexcan_user_config_t *	data,
		flexcan_mb_id_type_t	id_type,
		uint32_t	mb_idx,
		uint32_t	mask
	)

Parameters

instance	A FlexCAN instance number
id_type	A standard ID or an extended ID
mb_idx	Index of the message buffer
mask	Mask value

Returns: 0 if successful; non-zero failed.

flexcan_status_t flexcan_init	(	uint8_t	instance,
		const flexcan_user_config_t *	data,
		bool	enable_err_interrupts
	)

This function initializes

Parameters

instance	A FlexCAN instance number
data	The FlexCAN platform data
enable_err_interrupts	1 if enabled, 0 if not

Returns: 0 if successful; non-zero failed

uint32_t flexcan_shutdown ( uint8_t instance )

Parameters

instance A FlexCAN instance number

Returns: 0 if successful; non-zero failed

flexcan_status_t flexcan_tx_mb_config	(	uint8_t	instance,
		const flexcan_user_config_t *	data,
		uint32_t	mb_idx,
		flexcan_data_info_t *	tx_info,
		uint32_t	msg_id
	)

Parameters

instance	A FlexCAN instance number
data	The FlexCAN platform data
mb_idx	Index of the message buffer
tx_info	Data info
msg_id	ID of the message to transmit

Returns: 0 if successful; non-zero failed

flexcan_status_t flexcan_send	(	uint8_t	instance,
		const flexcan_user_config_t *	data,
		uint32_t	mb_idx,
		flexcan_data_info_t *	tx_info,
		uint32_t	msg_id,
		uint32_t	num_bytes,
		uint8_t *	mb_data
	)

Parameters

instance	A FlexCAN instance number
data	The FlexCAN platform data
mb_idx	Index of the message buffer
tx_info	Data info
msg_id	ID of the message to transmit
num_bytes	The number of bytes in mb_data
mb_data	Bytes of the FlexCAN message

Returns: 0 if successful; non-zero failed

flexcan_status_t flexcan_rx_mb_config	(	uint8_t	instance,
		const flexcan_user_config_t *	data,
		uint32_t	mb_idx,
		flexcan_data_info_t *	rx_info,
		uint32_t	msg_id
	)

Parameters

instance	A FlexCAN instance number
data	The FlexCAN platform data
mb_idx	Index of the message buffer
rx_info	Data info
msg_id	ID of the message to transmit

Returns: 0 if successful; non-zero failed

flexcan_status_t flexcan_rx_fifo_config	(	uint8_t	instance,
		const flexcan_user_config_t *	data,
		flexcan_rx_fifo_id_element_format_t	id_format,
		flexcan_id_table_t *	id_filter_table
	)

Parameters

instance	A FlexCAN instance number
data	The FlexCAN platform data
id_format	The format of the Rx FIFO ID Filter Table Elements
id_filter_table	The ID filter table elements which contain RTR bit, IDE bit, and RX message ID

Returns: 0 if successful; non-zero failed.

flexcan_status_t flexcan_start_receive	(	uint8_t	instance,
		const flexcan_user_config_t *	data,
		uint32_t	mb_idx,
		uint32_t	receiveDataCount,
		bool *	is_rx_mb_data,
		bool *	is_rx_fifo_data,
		flexcan_mb_t *	rx_mb,
		flexcan_mb_t *	rx_fifo
	)

Parameters

instance	A FlexCAN instance number
data	The FlexCAN platform data
mb_idx	Index of the message buffer
msg_id	ID of the message to transmit
receiveDataCount	The number of data to be received
rx_mb	The FlexCAN receive message buffer data.
rx_fifo	The FlexCAN receive FIFO data.

Returns: 0 if successful; non-zero failed

flexcan_status_t flexcan_receive	(	uint8_t	instance,
		const flexcan_user_config_t *	data,
		uint32_t	mb_idx,
		flexcan_data_info_t *	rx_info,
		uint32_t	msg_id,
		flexcan_rx_fifo_id_element_format_t	id_format,
		flexcan_id_table_t *	id_filter_table,
		uint32_t	receiveDataCount,
		flexcan_mb_t *	rx_mb,
		flexcan_mb_t *	rx_fifo
	)

Parameters

instance	A FlexCAN instance number
data	The FlexCAN platform data
mb_idx	Index of the message buffer
cs	CODE/status values (RX)
msg_id	ID of the message to transmit
id_format	The format of the Rx FIFO ID Filter Table Elements
id_filter_table	The ID filter table elements which contain RTR bit, IDE bit, and RX message ID
receiveDataCount	The number of data to be received
rx_mb	The FlexCAN receive message buffer data
rx_fifo	The FlexCAN receive FIFO data

Returns: 0 if successful; non-zero failed

Data Structures

Macros

Enumerations

Bit rate

Global mask

Init and Shutdown

Send configuration

Receive configuration

FlexCAN Driver

Overview

Initialization

Module timing

Transfers

Data Structure Documentation

Data Fields

Data Fields

Enumeration Type Documentation

Function Documentation