SH7263 Datasheet, PDF (1022/1862 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7260 Series

Section 19 Controller Area Network (RCAN-TL1)
CAN bus
state
RCAN-TL1
scheduler state
Bus Idle
Transmission
Frame-1
SOF Message EOF Interm SOF
Reception
Frame-2
Message
Transmission
Frame-3
EOF Interm SOF
Tx Arb for Tx/Rx Arb for
Frame-1 Frame-1
Tx Arb for
Frame-3
Tx/Rx Arb for
Frame-3/2
Tx Arb for
Frame-3
Tx/Rx Arb for
Frame-3
Scheduler
start point
TXPR/TXCR/
Error/Arb-Lost
1-1
1-2
2-1
2-2
3-1
3-2
Set Point
Interm:
SOF:
EOF:
Message:
Intermission Field
Start Of Frame
End Of Frame
Arbitration + Control + Data + CRC + Ack Field
Figure 19.17 Internal Arbitration for transmission
The RCAN-TL1 has two state machines. One is for transmission, and the other is for reception.
1-1: When a TXPR bit(s) is set while the CAN bus is idle, the internal arbitration starts running
immediately and the transmission is started.
1-2: Operations for both transmission and reception starts at SOF. Since there is no reception
frame, RCAN-TL1 becomes transmitter.
2-1: At crc delimiter, internal arbitration to search next message transmitted starts.
2-2: Operations for both transmission and reception starts at SOF. Because of a reception frame
with higher priority, RCAN-TL1 becomes receiver. Therefore, Reception is carried out
instead of transmitting Frame-3.
3-1: At crc delimiter, internal arbitration to search next message transmitted starts.
3-2: Operations for both transmission and reception starts at SOF. Since a transmission frame
has higher priority than reception one, RCAN-TL1 becomes transmitter.
Internal arbitration for the next transmission is also performed at the beginning of each error
delimiter in case of an error is detected on the CAN Bus. It is also performed at the beginning of
error delimiters following overload frame.
As the arbitration for transmission is performed at CRC delimiter, in case a remote frame request
is received into a Mailbox with ATX = 1 the answer can join the arbitration for transmission only
at the following Bus Idle, CRC delimiter or Error Delimiter.
Depending on the status of the CAN bus, following the assertion of the TXCR, the corresponding
Message abortion can be handled with a delay of maximum 1 CAN Frame.
Rev. 2.00 Mar. 14, 2008 Page 988 of 1824
REJ09B0290-0200