CAN SERIAL COMMUNICATIONS CONTROLLER

CAN_MSGxCON1 (Continued)

Address:

1Ex1H (x = 1–F)

x = 1–15 (87C196CB)

Reset State:

Unchanged

The CAN message object x control 1 (CAN_MSGxCON1) register indicates whether a message object has been updated, whether a message has been overwritten, whether the CPU is updating the message, and whether a transmission or reception is pending.

This register consists of four bit-pairs — the most-significant bit of each pair is in true form and the least-significant bit is in complement form. This format allows software to set or clear any bit with a single write operation, without affecting the remaining bits.

87C196CB

7

RMTPND RMTPND TX_REQ TX_REQ

0

MSGLST

MSGLST

NEWDAT

NEWDAT

CPUUPD

CPUUPD

 

 

 

 

 

 

Bit

Bit

 

 

Function

Number

Mnemonic

 

 

 

 

 

 

 

 

3:2

MSGLST or

Message Lost (Receive)

 

CPUUPD

For a receive message object, the CAN controller sets this bit-pair to

 

 

 

 

indicate that it stored a new message while the NEWDAT bit-pair was still

 

 

set, overwriting the previous message.

 

 

bit 3

bit 2

 

 

 

0

1

no overwrite occurred

 

 

1

0

a message was lost (overwritten)

 

 

CPU Updating (Transmit)

 

 

For a transmit message object, software should set this bit-pair to indicate

 

 

that it is in the process of updating the message contents. This prevents a

 

 

remote frame from triggering a transmission that would contain invalid

 

 

data.

 

 

 

 

bit 3

bit 2

 

 

 

0

1

the message is valid

 

 

1

0

software is updating data

 

 

 

 

1:0

NEWDAT

New Data

 

 

 

This bit-pair indicates whether a message object is valid (configured and

 

 

ready for transmission).

 

 

bit 1

bit 2

 

 

 

0

1

not ready

 

 

1

0

message object is valid

 

 

For receive message objects, the CAN peripheral sets this bit-pair when it

 

 

stores new data into the message object.

 

 

For transmit message objects, set this bit-pair and clear the CPUUPD bit-

 

 

pair to indicate that the message contents have been updated. Clearing

 

 

CPUUPD prevents a remote frame from triggering a transmission that

 

 

would contain invalid data.

 

 

During initialization, clear this bit for any unused message objects.

 

 

 

 

 

Figure 7-15. CAN Message Object x Control 1 (CAN_MSGxCON1) Register (Continued)

7-27

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Intel 87C196CB, 8XC196NT user manual Cpuupd, Newdat
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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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