C28x CAN Transmit

Enhanced Controller Area Network transmit mailbox

• 

Libraries:
C2000 Microcontroller Blockset / C2803x
C2000 Microcontroller Blockset / C2805x
C2000 Microcontroller Blockset / C2806x
C2000 Microcontroller Blockset / C280x
C2000 Microcontroller Blockset / C281x
C2000 Microcontroller Blockset / C2833x
C2000 Microcontroller Blockset / C2834x
C2000 Microcontroller Blockset / F280013x
C2000 Microcontroller Blockset / F280015x
C2000 Microcontroller Blockset / F28002x
C2000 Microcontroller Blockset / F28003x
C2000 Microcontroller Blockset / F28004x
C2000 Microcontroller Blockset / F2807x
C2000 Microcontroller Blockset / F2837xD
C2000 Microcontroller Blockset / F2837xS
C2000 Microcontroller Blockset / F2838x / C28x
C2000 Microcontroller Blockset / F28p65x

Description

The CAN Transmit block generates source code for transmitting enhanced Controller Area Network (CAN) messages through an CAN mailbox. CAN modules on the processor provide serial communication capability and have 32 mailboxes configurable for receive or transmit. This block supports CAN data frames in standard or extended format.

Note

Fixed-point inputs are not supported by this block.

The block supports CAN or DCAN depending upon the type of C2000 processors.

Configure the CAN modules for a specific hardware board by navigating to Hardware Implementation > Target hardware resources. Verify that these settings meet the requirements of your application.

Examples

Communication Using CAN Blocks

Use the CAN blocks to set up CAN communication between the target hardware and your host computer for Texas Instruments™ C2000™ Microcontroller Blockset.

• Open Model

Asynchronous Scheduling

Use the Texas Instruments™ C28x™ peripherals and Hardware Interrupt blocks to control the real-time execution of Simulink® function-call subsystems in an asynchronous fashion.

• Open Model

Ports

Input

Msg — Message data

vector

Input message data.

Data Types: uint8 | uint16 | uint32 | CAN_MESSAGE_TYPE

Parameters

Module — CAN module the block configures

CAN_A (default) | CAN_B

Determines the CAN module configured by this instance of the CAN Transmit block.

Mailbox number(0–31) — Sets value of mailbox number register (MBNR)

1 (default) | integer in the range [0 31]

A unique number from 0 to 15 for standard or from 0 to 31 for enhanced CAN mode. The number refers to a mailbox area in RAM. In standard mode, the mailbox number determines priority.

Note

In a model, multiple CAN Transmit blocks can have a same Mailbox number. But the same mailbox number cannot be used by CAN Receive block.

Message identifier — Value of message identifier register (MID)

bin2dec('111000111') (default) | numeric identifier of length 11 or 29 bits

The message identifier is 11 bits long for the standard frame size or 29 bits long for the extended frame size in decimal, binary, or hex. For binary and hex formats, use bin2dec(' ') and hex2dec(' '), respectively, to convert the entry. The message identifier is coded into a message that is sent to the CAN bus.

Note

CAN messages use the value of the message identifier parameter in the CAN Pack block for transmission when it is used with C28x CAN Transmit block to create the CAN message.

Message type — Message identifier type

Standard (11-bit identifier) (default) | Extended (29-bit identifier)

The message identifier type.

Enable blocking mode — Sets blocking mode

off (default) | on

If selected, the CAN block waits indefinitely for a transmit (XMT) acknowledgment. If not selected, the CAN block does not wait for a transmit (XMT) acknowledgment, which is useful if the hardware fails to acknowledge transmissions.

Post interrupt when message is transmitted — Posts asynchronous interrupt when message is transmitted

off (default) | on

When selected, this block posts an asynchronous interrupt when data is transmitted.

Interrupt Line — Interrupt line of asynchronous interrupt

0 (default) | 1

The interrupt line the asynchronous interrupt uses. The value of this parameter sets bit 2 (GIL) in the global interrupt mask register (CANGIM):

• 1 maps the global interrupts to the CAN1INT line.

• 0 maps the global interrupts to the CAN0INT line.

Note

For information about setting the timing parameters of the CAN module, see Configuring Timing Parameters for CAN Blocks.

Dependencies

This parameter appears only when Post interrupt when message is transmitted is selected.

More About

Data Vectors

The length of the vector for each transmitted mailbox message is 8 bytes. Input data are right-aligned in the message data buffer. The uint8 (vector length = 8 elements), uint16 (vector length = 4 elements), and uint32 (vector length = 2 elements) data types are accepted. While using the CAN Transmit block with the CAN Pack block in the canmsglib library, CAN_MESSAGE_TYPE is also accepted.

The following examples show how different types of input data are aligned in the data buffer:

For input of data type uint32,

inputdata [0] = 0x12345678

the data buffer is:

data buffer[0] = 0x78
data buffer[1] = 0x56
data buffer[2] = 0x34
data buffer[3] = 0x12
data buffer[4] = 0x00
data buffer[5] = 0x00
data buffer[6] = 0x00
data buffer[7] = 0x00

For input of data type uint16,

inputdata [0] = 0x1234

the data buffer is:

data buffer[0] = 0x34
data buffer[1] = 0x12
data buffer[2] = 0x00
data buffer[3] = 0x00
data buffer[4] = 0x00
data buffer[5] = 0x00
data buffer[6] = 0x00
data buffer[7] = 0x00

For input of data type uint16[2], which is a two-element vector,

inputdata [0] = 0x1234
inputdata [1] = 0x5678

the data buffer is:

data buffer[0] = 0x34
data buffer[1] = 0x12
data buffer[2] = 0x78
data buffer[3] = 0x56
data buffer[4] = 0x00
data buffer[5] = 0x00
data buffer[6] = 0x00
data buffer[7] = 0x00