YR0K42378FC000BA Renesas Electronics America, YR0K42378FC000BA Datasheet - Page 273

• Manufacturer Part Number: YR0K42378FC000BA
• Description: KIT EVAL FOR H8S/2378
• Manufacturer: Renesas Electronics America
• Series: H8®r
• Type: MCUr

Specifications of YR0K42378FC000BA

• Contents: Board
• For Use With/related Products: H8S/2378
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

The bus cycle can also be extended in burst access by inserting wait states. The wait state insertion
method and timing are the same as for full access. For details see section 6.6.9, Wait Control.
RAS Down Mode and RAS Up Mode: Even when burst operation is selected, it may happen that
access to DRAM space is not continuous, but is interrupted by access to another space. In this
case, if the RAS signal is held low during the access to the other space, burst operation can be
resumed when the same row address in DRAM space is accessed again.
• RAS Down Mode
Note: n = 2 to 5
Read
Write
To select RAS down mode, set both the RCDM bit and the BE bit to 1 in DRAMCR. If access
to DRAM space is interrupted and another space is accessed, the RAS signal is held low
during the access to the other space, and burst access is performed when the row address of the
next DRAM space access is the same as the row address of the previous DRAM space access.
Figure 6.32 shows an example of the timing in RAS down mode.
Note, however, that the RAS signal will go high if:
φ
Address bus
RASn (CSn)
UCAS, LCAS
WE (HWR)
OE (RD)
Data bus
WE (HWR)
OE (RD)
Data bus
Figure 6.31 Operation Timing in Fast Page Mode
T
Row address
p
T
r
(RAST = 0, CAST = 1)
High
High
T
c1
Column address 1
T
c2
Rev.7.00 Mar. 18, 2009 page 205 of 1136
T
c3
Section 6 Bus Controller (BSC)
T
c1
Column address 2
REJ09B0109-0700
T
c2
T
c3