Can Controller Error States - Renesas M32R/ECU Series User Manual

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13.3.3 CAN Controller Error States

The CAN controller assumes one of the following three error states depending on the transmit error and receive
error counter values.
(1) Error active state
• This is a state where almost no errors have occurred.
• When an error is detected, an active error flag is transmitted.
• The CAN controller is in this state immediately after being initialized.
(2) Error passive state
• This is a state where many errors have occurred.
• When an error is detected, a passive error flag is transmitted.
(3) Bus off state
• This is a state where a very large number of errors have occurred.
• CAN communication with other nodes cannot be performed until the CAN module returns to an error active state.
Error Status of the Unit
Error active state
Error passive state
Bus off state
Transmit error counter ≥ 128
OR
receive error counter ≥ 128
Error passive
Figure 13.3.4 CAN Controller Error States
Transmit Error Counter
0–127
128-255
256 and over
Error active
Transmit error counter < 128
AND
receive error counter < 128
state
Transmit error counter > 255
AND
OR
Initial setting
state
11 consecutive recessive bits
detected on CAN bus 128 times
or reset by software
Bus off state
13-74
CAN MODULE
13.3 CAN Protocol
Receive Error Counter
0–127
128 and over
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32180 Group User's Manual (Rev.1.0)