SH7058 Datasheet, PDF (653/1130 Pages) Renesas Technology Corp – Renesas SuperHTM RISC engine

CAN bus
Bus idele
SOF
ID
A
t1
t2
Transmit cancellation prohibited period
When the transmission setting (TXPR) is made to a mailbox at the point A shown in the above
figure and then transmit cancellation setting (TXCR) is made at the timing between t1 and t2,
transmission may be performed to the CAN bus regardless of the fact that a flag is set in the abort
acknowledge register. (The transmit acknowledge (TXACK) of the transmitted mailbox is set.)
The t1 and t2 timings are as follows after the transmission setting (TXPR) has been made.
Table 16.12 Transmit Cancellation Prohibited Period
Pφ
20 MHz
20 MHz
Baud Rate
1 Mbps
0.5 Mbps
MB order
ID order
MB order
ID order
t1
1.90 µs
5.05 µs
2.55 µs
5.45 µs
t2
6.30 µs
13.55 µs
7.65 µs
13.55 µs
16.8.3 Failure on Transmit Cancellation at Mailbox 31
When mailbox 31 is used as a transmit buffer and the transmit cancellation setting is made by
TXCR, the following failures may occur. Note that these failures do not occur in the bus-off state.
• When the transmit cancellation setting is made by TXCR for mailbox 31 during message
transmission (except for mailbox 31), a message may be transmitted and the transmit
acknowledge register (TXACK) may be set regardless of the fact that the abort acknowledge
register (ABACK) is set.
• When the transmit cancellation setting is made by TXCR for mailbox 31 during message
transmission of mailbox 31, TXPR may not be cleared even if transmission is completed at
mailbox 31 and retransmission may be performed according to the internal arbitration
sequence.
16.8.4 TXPR Setting during Transmission
When the HCAN-II is used with the baud rate set to 1 Mbps and the TXPR setting is made during
transmission, there are the following limitations on the number of transmit mailboxes (MB) and
the number of accesses to mailboxes until transmission is completed. Note that there is no
limitation when 500 kbps of baud rate is used.
Rev. 3.0, 09/04, page 612 of 1086