179
7.5.9
Byte Access Control
When 16-bit DRAMs are connected, the 2 CAS method can be used as the control signal required
for byte access.
Figure 7-19 shows the 2 CAS method control timing. Figure 7-20 shows an example of connecting
DRAM in high-speed page mode.
When all areas selected as DRAM space are set as 8-bit space, the
LCAS
pin functions as an I/O
port.
T
p
ø
CSn (RAS)
Byte control
A23 to A0
T
r
T
c1
T
c2
row
CAS
LCAS
HWR (WE)
column
Note: n= 2 to 5
Figure 7-19 2 CAS Method Control Timing (For High Byte Write Access)
When using DRAM EDO page mode, either use
OE
to control the read data or, as shown in Figure
7-20, select RAS up mode. Figure 7-21 is an example of DRAM connection in EDO page mode
when OES=1.
Содержание H8S/2631
Страница 28: ...xviii Appendix G Package Dimensions 1154 ...
Страница 341: ...316 Transfer SAR or DAR DAR or SAR Block area First block Nth block Figure 9 8 Memory Mapping in Block Transfer Mode ...
Страница 918: ...905 ø DREQ0 DREQ1 tDRQS tDRQH Figure 25 19 DMAC DREQ Input Timing ...
Страница 955: ...943 A 2 Instruction Codes Table A 2 shows the instruction codes ...