SH7763 Datasheet, PDF (383/2026 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperHTM RISC Engine Family SH-4A Series

Section 10 SuperHyway Bus Bridge (SBR)
10.3 Operation
10.3.1 SuperHyway Bus Interface
The SuperHyway bus bridge (SBR) performs access protocol conversion between the
SuperHyway bus and the SuperHyway bridge bus.
10.3.2 Bus Arbitration
The SBR performs arbitration for the access requests from the four ports of the three modules
(SECURITY, GETHER, and USBH) connected to the SuperHyway bridge bus. Figure 10.2 shows
the concept of arbitration by the SBR.
Level 1
Level 2
Level 2 (5-round robin)
GETHER1
GETHER0
USBH
Level 3
SECURITY
Level 3 (4-round robin)
GETHER1
USBH
GETHER0
SECURITY
USBH
Read
USBH
Write
USBH
Read
USBH
Write
Figure 10.2 Bus Arbitration by the SBR
The SBR performs arbitration for three groups  level 1, level 2, and level 3. At level 3, round-
robin arbitration is performed for a total of four ports of three modules; at level 2, round-robin
arbitration is performed for four ports of three modules plus the result of arbitration at level 3.
Since there are no modules to compete with at level 1, the access from the module that won the
arbitration at level 2 is immediately executed.
Rev. 1.00 Oct. 01, 2007 Page 317 of 1956
REJ09B0256-0100