Datasheet

V850ES/JG3-H, V850ES/JH3-H CHAPTER 20 CAN CONTROLLER
R01UH0042EJ0500 Rev.5.00 Page 908 of 1513
Aug 12, 2011
(4) Error state
(a) Types of error states
The following three types of error states are defined by the CAN specification.
• Error active
• Error passive
• Bus-off
These types of error states are classified by the values of the C0ERC.TEC7 to C0ERC.TEC0 bits
(transmission error counter bits) and the C0ERC.REC6 to C0ERC.REC0 bits (reception error counter bits) as
shown in Table 20-13.
The present error state is indicated by the C0INFO register.
When each error counter value becomes equal to or greater than the error warning level (96), the
C0INFO.TECS0 or C0INFO.RECS0 bit is set to 1. In this case, the bus state must be tested because it is
considered that the bus has a serious fault. An error counter value of 128 or more indicates an error passive
state and the TECS1 or RECS1 bit is set to 1.
• If the value of the transmission error counter is greater than or equal to 256 (actually, the transmission error
counter does not indicate a value greater than or equal to 256), the bus-off state is reached and the
C0INFO.BOFF bit is set to 1.
• If only one node is active on the bus at startup (i.e., when the bus is connected only to the local station),
ACK is not returned even if data is transmitted. Consequently, re-transmission of the error frame and data
is repeated. In the error passive state, however, the transmission error counter is not incremented and the
bus-off state is not reached.