r5f71374an80fpv Renesas Electronics Corporation., r5f71374an80fpv Datasheet - Page 800

• Manufacturer Part Number: r5f71374an80fpv
• Description: 32-bit Risc Microcomputer Superh?? Risc Engine Family
• Manufacturer: Renesas Electronics Corporation.

Section 19 Controller Area Network (RCAN-ET)
• Internal Arbitration for transmission
The RCAN-ET 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
1-2: Operations for both transmission and reception starts at SOF. Since there is no reception
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
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
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.
Rev. 1.00 Sep. 21, 2007 Page 774 of 1124
REJ09B0402-0100
scheduler state
Error/Arb-Lost
TXPR/TXCR/
The following diagram explains how RCAN-ET manages to schedule transmission-requested
messages in the correct order based on the CAN identifier. ‘Internal arbitration’ picks up the
highest priority message amongst transmit-requested messages.
RCAN-ET
Scheduler
start point
CAN bus
Set Point
immediately and the transmission is started.
frame, RCAN-ET becomes transmitter.
with higher priority, RCAN-ET becomes receiver. Therefore, Reception is carried out instead
of transmitting Frame-3.
higher priority than reception one, RCAN-ET becomes transmitter.
state
Bus Idle
1-1
Interm:
SOF:
EOF:
Message:
Tx Arb for
Figure 19.11 Internal Arbitration for Transmission
Frame-1
SOF
Tx/Rx Arb for
Intermission Field
Start Of Frame
End Of Frame
Arbitration + Control + Data + CRC + Ack Field
Frame-1
1-2
Transmission
Message
Frame-1
Tx Arb for
Frame-3
2-1
EOF Interm
SOF
Tx/Rx Arb for
Frame-3/2
2-2
Reception
Message
Frame-2
Tx Arb for
Frame-3
3-1
EOF Interm
Transmission
SOF
Tx/Rx Arb for
Frame-3
Frame-3
3-2