r4f2426 Renesas Electronics Corporation., r4f2426 Datasheet - Page 252

• Manufacturer Part Number: r4f2426
• Description: 16-bit Single-chip Microcomputer H8s Family / H8s/2400 Series
• Manufacturer: Renesas Electronics Corporation.

Section 6 Bus Controller (BSC)
6.7.8
When DRAM is accessed, a RAS precharge time must be secured. With this LSI, one T
always inserted when DRAM space is accessed. From one to four T
setting bits TPC1 and TPC0 in DRACCR. Set the optimum number of T
DRAM connected and the operating frequency of this LSI. Figure 6.37 shows the timing when
two T
cycles.
Rev. 1.00 Sep. 19, 2008 Page 224 of 1270
REJ09B0466-0100
Read
Write
Note: n = 2 to 5
p
states are inserted. The setting of bits TPC1 and TPC0 is also valid for T
Precharge State Control
φ
Address bus
RASn (CSn)
UCAS, LCAS
WE (HWR)
OE (RD)
Data bus
WE (HWR)
OE (RD)
Data bus
Figure 6.37 Example of Timing with Two-State Precharge Cycle
T
p1
(RAST = 0, CAST = 0)
Row address
T
p2
High
High
T
r
p
states can be selected by
T
c1
Column address
p
cycles according to the
p
states in refresh
T
c2
p
state is