CP3BT23 Datasheet, PDF (99/260 Pages) Texas Instruments – CP3BT23 Reprogrammable Connectivity Processor with Bluetooth and Dual CAN Interfaces

3
INT
ANY FRAME
INTERFRAME SPACE
8
SUSPEND
TRANSMIT
Bus Idle
DATA FRAME OR
REMOTE FRAME
rrrrrrrrrr rrrrrrrrr
INT = Intermission
Suspend Transmission is only for error passive nodes.
r r rd
Note:
d = dominant
r = recessive
DS026
Figure 40. Interframe Space
18.2.4 Error Types
Bit Error
A CAN device which is currently transmitting also monitors
the bus. If the monitored bit value is different from the trans-
te ^{mitted bit value, a bit error is detected. However, the recep-}
tion of a “dominant” bit instead of a “recessive” bit during the
transmission of a passive error flag, during the stuffed bit
stream of the arbitration field, or during the acknowledge
slot is not interpreted as a bit error.
Stuff Error
le ^{A stuff error is detected if 6 consecutive bits occur without a}
state change in a message field encoded with bit stuffing.
Form Error
A form error is detected, if a fixed frame bit (e.g., CRC de-
limiter, ACK delimiter) does not have the specified value. For
a receiver, a “dominant” bit during the last bit of End of
Frame does not constitute a frame error.
Bit CRC Error
A CRC error is detected if the remainder from the CRC cal-
culation of a received CRC polynomial is non-zero.
Acknowledgment Error
An acknowledgment error is detected whenever a transmit-
ting node does not get an acknowledgment from any other
node (i.e., when the transmitter does not receive a “domi-
nant” bit during the ACK frame).
Error States
The device can be in one of five states with respect to error
handling (see Figure 41).
o _{External Reset or}
Enable CR16CAN
s _SYNC
b11 consecutive 'recessive" bits
received
ERROR
O^ACTIVE
(TEC OR REC) > 95
(TEC AND REC) < 96
ERROR
WARNING
(TEC OR REC) > 127
(TEC AND REC) < 128
ERROR
PASSIVE
TEC > 255
128 occurrences of
11 consecutive 'recessive" bits
BUS
OFF
Figure 41. Bus States
DS027
Synchronize
Once the CAN module is enabled, it waits for 11 consecu-
tive recessive bits to synchronize with the bus. After that, the
CAN module becomes error active and can participate in
the bus communication. This state must also be entered af-
ter waking-up the device using the Multi-Input Wake-Up fea-
ture. See System Start-Up and Multi-Input Wake-Up on
page 123.
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