Renesas H8SX/1650, Руководство по оборудованию

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Section 6 Bus Controller (BSC)
Rev.2.00 Jun. 28, 2007 Page 185 of 666
REJ09B0311-0200
6.7.6 Read Strobe (
RD
)
When the byte control SRAM space is specified, the RDNCR setting for the corresponding space
is invalid.
The read strobe negation timing is the same timing as when RDNn = 1 in the basic bus interface.
6.7.7 Extension of Chip Select (
CS
) Assertion Period
In the byte control SRAM interface, the extension cycles can be inserted before and after the bus
cycle in the same way as the basic bus interface. For details, see section 6.6.6, Extension of Chip
Select (
CS
) Assertion Period.
6.8 Burst ROM Interface
In this LSI, external address space areas 0 and 1 can be designated as burst ROM space, and burst
ROM interfacing performed. The burst ROM interface enables ROM with page access capability
to be accessed at high speed.
Areas 1 and 0 can be designated as burst ROM space by means of bits BSRM1 and BSRM0 in
BROMCR. Consecutive burst accesses of up to 32 words can be performed, according to the
setting of bits BSWDn1 and BSWDn0 (n = 0, 1) in BROMCR. From one to eight cycles can be
selected for burst access.
Settings can be made independently for area 0 and area 1.
In the burst ROM interface, burst access covers only CPU read accesses. Other accesses are
covered by basic bus interface.
6.8.1 Burst ROM Space Setting
Burst ROM interface can be specified for areas 0 and 1. Areas 0 and 1 can be specified as burst
ROM space by setting bits BSRMn (n = 0, 1) in BROMCR.