Motorola MCF5282 ユーザーズマニュアル

25-6

MOTOROLA

 

Time Stamp Contains a copy of the high byte of the free running timer, which is captured at the beginning of the 

identifier field of the frame on the CAN bus.

Code

Refer to Table 25-3 and Table 25-4.

Rx Length

Length (in bytes) of the Rx data stored in offset 0x6 through 0xD of the buffer. This field is written by 
the FlexCAN module, copied from the data length code (DLC) field of the received frame.

Tx Length

Length (in bytes) of the data to be transmitted, located in offset 0x6 through 0xD of the buffer. This 
field is written by the CPU, and is used as the DLC field value. If remote transmission request (RTR)) 
= 1, the frame is a remote frame and will be transmitted without the data field, regardless of the value 
in Tx length.

Data

This field can store up to eight data bytes for a frame. For Rx frames, the data is stored as it is 
received from the bus. For Tx frames, the CPU provides the data to be transmitted within the frame.

Reserved

This word entry field (16 bits) should not be accessed by the CPU.

0000

NOT ACTIVE — message buffer is not active.

—

—

0100

EMPTY — message buffer is active and empty.

0010

—

0010

FULL — message buffer is full.

0110

If a CPU read occurs before 
the new frame, new receive 
code is 0010.

0110

OVERRUN — second frame was received into a full 
buffer before the CPU read the first one.

0101

 1

1

For transmit message buffers, upon read, the BUSY bit should be ignored.

BUSY — message buffer is now being filled with a new 
receive frame. This condition will be cleared within 20 
cycles.

0010

An empty buffer was filled.

0011

1

0110

A full buffer was filled.

0111

1

0110

An overrun buffer was filled.

X

1000

Message buffer not ready for transmit.

—

0

1100

Data frame to be transmitted once, unconditionally.

1000

1

1100

Remote frame to be transmitted once, and message buffer 
becomes an Rx message buffer for data frames.

0100

0

1010

 1

1

When a matching remote request frame is detected, the code for such a message buffer is changed to be 1110.

Data frame to be transmitted only as a response to a remote 
frame.

1010

0

1110

Data frame to be transmitted only once, unconditionally, and 
then only as a response to remote frame.

1010