MPC555
/
MPC556
CAN 2.0B CONTROLLER MODULE
MOTOROLA
USER’S MANUAL
Rev. 15 October 2000
16-33
Table 16-21 ESTAT Bit Descriptions
Bit(s)
Name
Description
0:1
BITERR
Transmit bit error. The BITERR[1:0] field is used to indicate when a transmit bit error occurs.
Refer to
NOTE
: The transmit bit error field is not modified during the arbitration field or the ACK slot
bit time of a message, or by a transmitter that detects dominant bits while sending a passive
error frame.
2
ACKERR
Acknowledge error. The ACKERR bit indicates whether an acknowledgment has been cor-
rectly received for a transmitted message.
0 = No ACK error was detected since the last read of this register
1 = An ACK error was detected since the last read of this register
3
CRCERR
Cyclic redundancy check error. The CRCERR bit indicates whether or not the CRC of the
last transmitted or received message was valid.
0 = No CRC error was detected since the last read of this register
1 = A CRC error was detected since the last read of this register
4
FORMERR
Message format error. The FORMERR bit indicates whether or not the message format of
the last transmitted or received message was correct.
0 = No format error was detected since the last read of this register
1 = A format error was detected since the last read of this register
5
STUFERR
Bit stuff error. The STUFFERR bit indicates whether or not the bit stuffing that occurred in
the last transmitted or received message was correct.
0 = No bit stuffing error was detected since the last read of this register
1 = A bit stuffing error was detected since the last read of this register
6
TXWARN
Transmit error status flag. The TXWARN status flag reflects the status of the TouCAN trans-
mit error counter.
0 = Transmit error counter
<
96
1 = Transmit error counter
≥
96
7
RXWARN
Receiver error status flag. The RXWARN status flag reflects the status of the TouCAN re-
ceive error counter.
0 = Receive error counter
<
96
1 = Receive error counter
≥
96
8
IDLE
Idle status. The IDLE bit indicates when there is activity on the CAN bus.
0 = The CAN bus is not idle
1 = The CAN bus is idle
9
TX/RX
Transmit/receive status. The TX/RX bit indicates when the TouCAN module is transmitting
or receiving a message. TX/RX has no meaning when IDLE = 1.
0 = The TouCAN is receiving a message if IDLE = 0
1 = The TouCAN is transmitting a message if IDLE = 0
10:11
FCS
Fault confinement state. The FCS[1:0] field describes the state of the TouCAN. Refer to
.
If the SOFTRST bit in CANMCR is asserted while the TouCAN is in the bus off state, the
error and status register is reset, including FCS[1:0]. However, as soon as the TouCAN exits
reset, FCS[1:0] bits will again reflect the bus off state. Refer to
for
more information on entry into and exit from the various fault confinement states.
12
—
Reserved
13
BOFFINT
Bus off interrupt. The BOFFINT bit is used to request an interrupt when the TouCAN enters
the bus off state.
0 = No bus off interrupt requested
1 = When the TouCAN state changes to bus off, this bit is set, and if the BOFFMSK bit in
CANCTRL0 is set, an interrupt request is generated. This interrupt is not requested after
reset.
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Freescale Semiconductor, Inc.
For More Information On This Product,
Go to: www.freescale.com
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