CAN SERIAL COMMUNICATIONS CONTROLLER

7.5.1Specifying a Message Object’s Configuration

Each message object configuration register (Figure 7-12) specifies a message identifier type (standard or extended), transfer direction (transmit or receive), and data length (in bytes).

CAN_MSGxCFG

Address:

1Ex6H (x = 1–F)

x = 1–15 (87C196CB)

Reset State:

Unchanged

Program the CAN message object x configuration (CAN_MSGxCFG) register to specify a message object’s data length, transfer direction, and identifier type.

87C196CB

7

DLC3

DLC2

DLC1

DLC0

 

 

 

 

0

DIR

XTD

—

—

 

 

 

 

Bit

Bit

 

Function

Number

Mnemonic

 

 

 

 

 

 

7:4

DLC3:0

Data Length Code

 

 

Specify the number of data bytes this message object contains. Valid

 

 

values are 0–8. The CAN controller updates a receive message object’s

 

 

data length code after each reception to reflect the number of data bytes in

 

 

the current message.

 

 

 

3

DIR

Direction

 

 

Specify whether this message object is to be transmitted or is to receive a

 

 

message object from a remote node.

 

 

0

= receive

 

 

1

= transmit

 

 

 

2

XTD

Extended Identifier Used

 

 

Specify whether this message object’s identification registers contain an

 

 

extended (29-bit) or a standard (11-bit) identifier.

 

 

0

= standard identifier

 

 

1

= extended identifier

 

 

 

1:0

—

Reserved; for compatibility with future devices, write zeros to these bits.

 

 

 

 

Figure 7-12. CAN Message Object x Configuration (CAN_MSGxCFG) Register

Set the XTD bit for a message object with an extended identifier; clear it for a message with a standard identifier. If you accidentally clear the XTD bit for a message that has an extended iden- tifier, the CAN controller will clear the extended bits in the identification register. If you set the XTD bit for a message object, that message object cannot receive message objects with standard identifiers.

For a transmit message, set the DIR bit and write the number of programmed data bytes (0–8) to the DLC field. For a receive message, clear the DIR bit. The CAN controller stores the data length from the received message in the DLC field.

7-21

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Intel 8XC196NT Specifying a Message Object’s Configuration, Canmsg xCFG, = 1-15 87C196CB, DLC3 DLC2 DLC1 DLC0 DIR XTD
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8XC196NT, 87C196CB specifications

The Intel 87C196CB and 8XC196NT are microcontrollers from the C196 family, which was designed to meet the demands of embedded control technology. These microcontrollers are popular in various applications due to their robust architecture, extensive I/O capabilities, and specialized functionality, making them ideal for automotive, industrial, and communication systems.

The 87C196CB is distinguished by its 16-bit architecture, offering a balance of processing power and efficiency. It features a 16-bit data bus, which allows for fast data processing, and a 16-bit address bus, supporting up to 64KB of program memory. The microcontroller integrates on-chip memory, including 2KB of ROM and 128 bytes of RAM, which facilitates faster execution of programs and data handling.

One of the standout features of the 87C196CB is its versatility in I/O operations. It comes equipped with 32 general-purpose I/O lines that can be configured for various functions, including input, output, and interrupt handling. This flexibility enables developers to optimize the microcontroller for their specific application needs.

The 8XC196NT builds on the capabilities of its predecessor, offering advanced functionalities such as an enhanced instruction set and integrated peripherals. It includes additional features like timers, serial communication interfaces, and analog-to-digital converters, which expand its usability in complex embedded systems. The 8XC196NT supports multiple addressing modes, allowing for more efficient programming and memory management.

Both microcontrollers utilize innovative technologies that improve performance and power efficiency. The on-chip operating system support aids in real-time processing and multitasking, making them suitable for time-sensitive applications. Power management features are also incorporated, allowing these microcontrollers to operate in low-power modes, which is crucial for battery-operated devices.

The 87C196CB and 8XC196NT microcontrollers are characterized by their reliability and long service life, meeting the stringent demands of industrial applications. Their ability to perform tasks rapidly, combined with their diverse peripheral support, makes them popular choices among engineers and developers designing embedded systems. Overall, the Intel 87C196CB and 8XC196NT microcontrollers remain relevant in the rapidly evolving landscape of embedded technology, facilitating innovative solutions across various industries.
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