H8S-2350 RENESAS [Renesas Technology Corp], H8S-2350 Datasheet - Page 205

• Manufacturer Part Number: H8S-2350
• Description: 16-Bit Single-Chip Microcomputer
• Manufacturer: RENESAS [Renesas Technology Corp]

(2) 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: To select RAS down mode, set the RCDM bit in MCR to 1. 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 if the row address of the next DRAM
space access is the same as the row address of the previous DRAM space access. Figure 6.21
shows an example of the timing in RAS down mode.
Note, however, that the RAS signal will go high if a refresh operation interrupts RAS down mode.
CAS, LCAS
Note: n = 2 to 5
CSn (RAS)
D
A
15
23
to D
to A
0
0
Figure 6.21 Example of Operation Timing in RAS Down Mode
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DRAM access
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Rev. 3.00 Sep 15, 2006 page 171 of 988
External space
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access
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Section 6 Bus Controller
DRAM access
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REJ09B0330-0300
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