SH7641 Datasheet, PDF (402/1036 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH™ RISC engine Family / SH7641 Series

Section 12 Bus State Controller (BSC)
number of cycles from the Tc1 cycle where the READ command is output to the Td1 cycle where
the read data is latched can be specified for the CS2 and CS3 spaces independently, using the
A2CL1 and A2CL0 bits in the CS2WCR register or the A3CL1 and A3CL0 bits in the CS3WCR
register and WTRCD0 bit in the CS3WCR register. The number of cycles from Tc1 to Td1
corresponds to the SDRAM CAS latency. The CAS latency for the SDRAM is normally defined
as up to three cycles. However, the CAS latency in this LSI can be specified as 1 to 4 cycles. This
CAS latency can be achieved by connecting a latch circuit between this LSI and the SDRAM.
A Tde cycle is an idle cycle required to transfer the read data into this LSI and occurs once for
every burst read or every single read.
CKIO
A25 to A0
A12/A11*¹
CSn
RASL, RASU
CASL, CASU
RD/WR
DQMxx
D31 to D0
BS
DACKn*²
Td1 Td2
Td3
Td4
Tr
Tc1
Tc2
Tc3
Tc4
Tde (Tap)
Notes: 1. Address pin to be connected to pin A10 of SDRAM.
2. The waveform for DACKn is when active low is specified.
Figure 12.18 Burst Read Basic Timing (CAS Latency 1, Auto Pre-Charge)
Rev. 4.00 Sep. 14, 2005 Page 352 of 982
REJ09B0023-0400