32172 Datasheet, PDF (617/875 Pages) Renesas Technology Corp – 32-bit RISC Single-chip Microcomputers

13
CAN MODULES
13.3 CAN Protocol
Initial setting
Error-active state
Transmit error counter ≥ 128
or
Receive error counter ≥ 128
Transmit error counter < 128
and
Receive error counter < 128
11 consecutive recessive bits
detected on CAN bus 128 times
or
reset in software
Error-passive
state
Transmit error counter > 255
Bus-off state
Figure 13.3.3 CAN Controller Error Status
The CAN Controller assumes one of the following three error states depending on the Transmit
Error Counter and Receive Error Counter values.
(1) Error-active state
• This state is assumed when almost no errors have occurred.
• When an error is detected, the CAN Controller sends an active-error flag.
• The CAN Controller is in this state immediately after initialization.
(2) Error-passive state
• This state is assumed when many errors have occurred.
• When an error is detected, the CAN Controller sends a passive-error flag.
(3) Bus-off state
• This state is assumed when a large number of errors have occurred.
• The CAN module cannot communicate with any other node until it returns to an active-error state.
Status of Unit Error
Error-active state
Error-passive state
Bus-off state
Transmit Error Counter
0-127
and
128-255
or
256 and over
Receive Error Counter
0-127
128 and over
–
13-80
Rev.1.0