SH7261 datasheet(879/1348 Pages) RENESAS

879 / 1348 page

Section 19 Controller Area Network (RCAN-ET) [R5S72611] [R5S72613]

Rev. 2.00 Sep. 07, 2007 Page 847 of 1312

REJ09B0320-0200

Temp

TXPR1

TXPR0

H'020

H'022

16-bit peripheral bus

TXPR0 is stored into Temp,

when TXPR1 (= H'0000) is read.

Consecutive access

16-bit peripheral bus

Temp is read instead of TXPR0.

Temp

TXPR1

TXPR0

H'020

H'022

Always

H'0000

The TXPR1 register cannot be modified and it is always fixed to '0'. The TXPR0 controls

Mailbox-15 to Mailbox-1. The CPU may set the TXPR bits to affect any message being

considered for transmission by writing a '1' to the corresponding bit location. Writing a '0' has no

effect, and TXPR cannot be cleared by writing a '0' and must be cleared by setting the

corresponding TXCR bits. TXPR may be read by the CPU to determine which, if any,

transmissions are pending or in progress. In effect there is a transmit pending bit for all Mailboxes

except for the Mailbox-0. Writing a '1' to a bit location when the mailbox is not configured to

transmit is not allowed.

The RCAN-ET will clear a transmit pending flag after successful transmission of its

corresponding message or when a transmission abort is requested successfully from the TXCR.

The TXPR flag is not cleared if the message is not transmitted due to the CAN node losing the

arbitration process or due to errors on the CAN bus, and RCAN-ET automatically tries to transmit

it again unless its DART bit (Disable Automatic Re-Transmission) is set in the Message-Control

of the corresponding Mailbox. In such case (DART set), the transmission is cleared and notified

through Mailbox Empty Interrupt Flag (IRR8) and the correspondent bit within the Abort

Acknowledgement Register (ABACK).

If the status of the TXPR changes, the RCAN-ET shall ensure that in the identifier priority scheme

(MCR2 = 0), the highest priority message is always presented for transmission in an intelligent

way even under circumstances such as bus arbitration losses or errors on the CAN bus. Please

refer to section 19.6, Application Note, for details.

SH7261 Datasheet(PDF) 879 Page - Renesas Technology Corp