upd70f3402 Renesas Electronics Corporation., upd70f3402 Datasheet - Page 539

• Manufacturer Part Number: upd70f3402
• Description: 32-/16-bit Single-chip Microcontroller With Can Interface
• Manufacturer: Renesas Electronics Corporation.

16.3 Functions
16.3.1 Determining bus priority
(1)
(2)
(3)
Caution:
16.3.2 Bit stuffing
Bit stuffing is used to establish synchronization by appending 1 bit of inverted-level data if the same
level continues for 5 bits, in order to prevent a burst error.
Transmission
Reception
When a node starts transmission:
During bus idle, the node that output data first transmits the data.
When more than one node starts transmission:
The node that consecutively outputs the dominant level for the longest from the first bit of the arbi-
tration field has the bus priority (if a dominant level and a recessive level are simultaneously trans-
mitted, the dominant level is taken as the bus value).
The transmitting node compares its output arbitration field and the data level on the bus.
Priority of data frame and remote frame
When a data frame and a remote frame are on the bus, the data frame has priority because its
RTR bit, the last bit in the arbitration field, carries a dominant level.
If the extended-format data frame and the standard-format remote frame conflict on
the bus (if ID28 to ID18 of both of them are the same), the standard-format remote
frame takes priority.
During the transmission of a data frame or remote frame, when the same level continues for 5
bits in the data between the start of frame and the ACK field, 1 inverted-level bit of data is
inserted before the following bit.
During the reception of a data frame or remote frame, when the same level continues for 5 bits in
the data between the start of frame and the ACK field, reception is continued after deleting the
next bit.
Level mismatch
Level match
User’s Manual U16702EE3V2UD00
Table 16-9: Determining Bus Priority
Chapter 16 FCAN Controller
Table 16-10: Bit Stuffing
Continuous transmission
Continuous transmission
539