CAN SERIAL COMMUNICATIONS CONTROLLER

CAN_STAT

Address:

1E01H

(87C196CB)

Reset State:

XXH

The CAN status (CAN_STAT) register reflects the current status of the CAN peripheral.

87C196CB

7

BUSOFF

WARN

RXOK

 

 

 

 

0

TXOK

LEC2

LEC1

LEC0

 

 

 

 

Bit

Bit

 

 

 

Function

Number

Mnemonic

 

 

 

 

 

 

 

 

 

 

 

7

BUSOFF

Bus-off Status

 

 

 

The CAN peripheral sets this read-only bit to indicate that it has isolated

 

 

itself from the CAN bus (floated the TX pin) because an error counter has

 

 

reached 256. A bus-off recovery sequence clears this bit and clears the

 

 

error counters. (See “Bus-off State” on page 7-41.)

 

 

 

 

6

WARN

Warning Status

 

 

 

The CAN peripheral sets this read-only bit to indicate that an error counter

 

 

has reached 96, indicating an abnormal rate of errors on the CAN bus.

 

 

 

5

Reserved. This bit is undefined.

 

 

 

4

RXOK

Reception Successful

 

 

The CAN peripheral sets this bit to indicate that a message has been

 

 

successfully received (error free, regardless of acknowledgment) since the

 

 

bit was last cleared. Software must clear this bit when it services the

 

 

interrupt.

 

 

 

 

 

3

TXOK

Transmission Successful

 

 

The CAN peripheral sets this bit to indicate that a message has been

 

 

successfully transmitted (error free and acknowledged by at least one

 

 

other node) since the bit was last cleared. Software must clear this bit

 

 

when it services the interrupt.

 

 

 

 

2:0

LEC2:0

Last Error Code

 

 

 

This field indicates the error type of the first error that occurs in a message

 

 

frame on the CAN bus. (“Error Detection and Management Logic” on page

 

 

7-9 describes the error types.)

 

 

LEC2 LEC1 LEC0 Error Type

 

 

0

0

0

no error

 

 

0

0

1

stuff error

 

 

0

1

0

form error

 

 

0

1

1

acknowledgment error

 

 

1

0

0

bit 1 error

 

 

1

0

1

bit 0 error

 

 

1

1

0

CRC error

 

 

1

1

1

unused

 

 

 

 

 

 

Figure 7-20. CAN Status (CAN_STAT) Register

If an individual message object caused the interrupt request (CAN_INT = 02–10H), software can read the associated message object control 0 register (Figure 7-21). The INT_PND bit-pair will be set, indicating that a receive or transmit interrupt request is pending

7-33

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Intel 87C196CB, 8XC196NT user manual Canstat, Busoff Warn Rxok Txok LEC2 LEC1 LEC0, LEC2 LEC1 LEC0 Error Type

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.