SH7750_08 Datasheet, PDF (627/1162 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer

Section 13 Bus State Controller (BSC)
13.3.16 Notes on Usage
Refresh: Auto refresh operations stop when a transition is made to standby mode, hardware
standby mode or deep-sleep mode. If the memory system requires refresh operations, set the
memory in the self-refresh state prior to making the transition to standby mode, hardware standby
mode or deep-sleep mode.
Bus Arbitration: On transition to standby mode or deep-sleep mode, the processor in master
mode does not release bus privileges. In systems performing bus arbitration, make the transition to
standby mode or deep-sleep mode only after setting the bus privilege release enable bit
(BCR1.BREQEN) to 0 for the processor in master mode. If the bus privilege release enable bit
remains set to 1, operation cannot be guaranteed when the transition is made to standby mode or
deep-sleep mode.
Synchronous DRAM Mode Register Setting (SH7750, SH7750S Only): The following
conditions must be satisfied when setting the synchronous DRAM mode register.
• The DMAC must not be activated until synchronous DRAM mode register setting is
completed.*¹
• Register setting for the on-chip peripheral modules*² must not be performed until synchronous
DRAM mode register setting is completed.*³
Notes: 1. If a conflict occurs between synchronous DRAM mode register setting and memory
access using the DMAC, neither operation can be guaranteed.
2. This applies to the following on-chip peripheral modules: CPG, RTC, INTC, TMU,
SCI, SCIF, and H-UDI.
3. If synchronous DRAM mode register setting is performed immediately following write
access to the on-chip peripheral modules*², the values written to the on-chip peripheral
modules cannot be guaranteed. Note that following power-on, synchronous DRAM
mode register settings should be performed before accessing synchronous DRAM.
After making mode register settings, do not change them.
BSREQ Output in Partial-Sharing Master Mode: When conditions a. to d. below are all
satisfied, the BSREQ pin may be driven low during a refresh operation and a bus release request
issued to the master mode device, even though there was no request to access area 2. The period
that BSREQ is asserted is 3 to 21 CKIO cycles, as specified by the setting of MCR.TRC (see d.
below).
Rev.7.00 Oct. 10, 2008 Page 543 of 1074
REJ09B0366-0700