Tr
Trw
Tc1
Tc2
Tc3
Tc4
Tc5
Tc6
Tc7
Tc8
Trw1
Trw1
Tpc
CKIO
Bank
Row
Precharge-sel
Address
Row
Row
H/L
c1
H/L
c5
RD/
DQMn
D31–D0 (read)
c1
c2
c3
c4
c5
c6
c7
c8
CKE
DACKn
(SA: IO → memory)
Note: For DACKn, an example is shown where CHCRn.AL (access level) = 0 for the DMAC.
Figure 13.44 Basic Timing of a Burst Write to Synchronous DRAM
Connecting a 128-Mbit/256-Mbit Synchronous DRAM with 64-bit Bus Width (SH7750R
Only): It is possible to connect 128-Mbit or 256-Mbit synchronous DRAMs with 64-bit bus width
to the SH7750R. RAS down mode is also available using a 128 Mbytes of external memory space
in area 2 or 3. Either eight 128-Mbit (4 M × 8 bit × 4 bank) DRAMs or four 256-Mbit (4 M × 8 bit
× 4 bank) DRAMs can be connected. Figure 13.45 shows an example in which four 256-Mbit
DRAMs are connected.
Notes on Usage:
•
BCR1.DRAMTP2−DRAMTP0 = 011: Sets areas 2 and 3 as synchronous-DRAM-interface
spaces.
•
•
MCR.SZ = 00: Sets the bus width of the synchronous DRAM to 64 bits.
MCR.AMX = 6: Selects the 128-Mbit or 256-Mbit address-multiplex setting for the
synchronous DRAM.
•
•
In the auto-refresh operation, the REF command is issued twice in response to a single refresh
request. Set RTCOR and bits CKS2−CKS0 so as to satisfy the refresh-interval rating of the
synchronous DRAM which you are using.
When setting the mode register of the synchronous DRAM, set the address for area 2 first.
Rev. 6.0, 07/02, page 440 of 986
RENESAS [ RENESAS TECHNOLOGY CORP ]
