Rainbow Electronics T89C51CC01 - Manual (Page 97)

97
T89C51CC01
Rev. D – 17-Dec-01
No default value after reset
Table 55. CANSTCH Register
CANSTCH (S:B2h)
CAN message object Status
Register
3-0 DLC3:0
Data length code
Number of bytes in the data field of the message.
The range of DLC is from 0 up to 8.
This value is updated when a frame is received (data or remote frame).
If the expected DLC differs from the incoming DLC, a warning appears in the
CANSTCH register.
Bit
Number
Bit
Mnemonic Description
7 6 5 4 3 2 1 0
DLCW TXOK RXOK BERR SERR CERR FERR AERR
Bit
Number
Bit
Mnemonic Description
7 DLCW
Data length code warning
The incoming message does not have the DLC expected. Whatever the frame
type, the DLC field of the CANCONCH register is updated by the received DLC.
6 TXOK
Transmit OK
The communication enabled by transmission is completed.
When the controller is ready to send a frame, if two or more message objects are
enabled as producers, the lower index message object (0 to 13) is supplied first.
This flag can generate an interrupt.
5 RXOK
Receive OK
The communication enabled by reception is completed.
In the case of two or more message object reception hits, the lower index
message object (0 to 13) is updated first.
This flag can generate an interrupt.
4 BERR
Bit error (only in transmission)
The bit value monitored is different from the bit value sent.
Exceptions:
the monitored recessive bit sent as a dominant bit during the arbitration field and
the acknowledge slot detecting a dominant bit during the sending of an error
frame.
This flag can generate an interrupt.
3 SERR
Stuff error
Detection of more than five consecutive bits with the same polarity.
This flag can generate an interrupt.
2 CERR
CRC error
The receiver performs a CRC check on each destuffed received message from
the start of frame up to the data field.
If this checking does not match with the destuffed CRC field, a CRC error is set.
This flag can generate an interrupt.