HD6417320 RENESAS [Renesas Technology Corp], HD6417320 Datasheet - Page 447

• Manufacturer Part Number: HD6417320
• Description: Renesas 32-Bit RISC Microcomputer SuperHTM RISC engine Family / SH7700 Series
• Manufacturer: RENESAS [Renesas Technology Corp]

9.5.6
The burst ROM (clock asynchronous) interface is used to access a memory with a high-speed read
function using a method of address switching called the burst mode or page mode. In a burst ROM
(clock asynchronous) interface, basically the same access as the normal space is performed, but
the 2nd and subsequent accesses are performed only by changing the address, without negating the
RD signal at the end of the 1st cycle. In the 2nd and subsequent accesses, addresses are changed at
the falling edge of the CKIO.
For the 1st access cycle, the number of wait cycles specified by the W[3:0] bits in CSnWCR is
inserted. For the 2nd and subsequent access cycles, the number of wait cycles specified by the
BW[1:0] bits in CSnWCR is inserted.
In the access to the burst ROM (clock asynchronous), the BS signal is asserted only to the first
access cycle. An external wait input is valid only to the first access cycle.
In the single access or write access that do not perform the burst operation in the burst ROM
(clock asynchronous) interface, access timing is same as a normal space.
Burst ROM (Clock Asynchronous) Interface
A12/A11*
A25 to A0
D31 to D0
DACKn*
DQMxx
RD/WR
CKIO
CKE
RAS
CAS
CSn
BS
Figure 9.30
1
2
Notes:
1. Address pin to be connected to the A10 pin of SDRAM.
2. The waveform for DACKn is when active low is specified.
Tp
Tpw
Transition Timing in Deep Power-Down Mode
Tdpd
Trc
Trc
Rev. 3.00 Jan. 18, 2008 Page 385 of 1458
Section 9
Hi-Z
Trc
Trc
Bus State Controller (BSC)
Trc
REJ09B0033-0300