SH7211 Datasheet, PDF (249/1228 Pages) Renesas Technology Corp – 32-Bit RISC Microcomputer SuperHTM RISC engine Family

Section 8 Bus State Controller (BSC)
8.4.5 Refresh Timer Control/Status Register (RTCSR)
RTCSR specifies various items about refresh for SDRAM. RTCSR is initialized to H'00000000 by
a power-on reset and retains the value by a manual reset and in software standby mode.
When RTCSR is written, the upper 16 bits of the write data must be H'A55A to cancel write
protection.
The phase of the clock for incrementing the count in the refresh timer counter (RTCNT) is
adjusted only by a power-on reset. Note that there is an error in the time until the compare match
flag is set for the first time after the timer is started with the CKS[2:0] bits being set to a value
other than B'000.
Bit: 31 30 29 28 27 26 25 24 23 22 21 20 19 18 17 16
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Initial value: 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
R/W: R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
R
Bit: 15 14 13 12 11 10 9
8
7
6
5
4
3
2
1
0
-
-
-
-
-
-
-
-
CMF CMIE
CKS[2:0]
RRC[2:0]
Initial value: 0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
R/W: R
R
R
R
R
R
R
R R/W R/W R/W R/W R/W R/W R/W R/W
Bit
Bit Name
31 to 8 ⎯
7
CMF
Initial
Value
All 0
0
R/W Description
R
Reserved
These bits are always read as 0.
R/W Compare Match Flag
Indicates that a compare match occurs between the
refresh timer counter (RTCNT) and refresh time
constant register (RTCOR). This bit is set or cleared in
the following conditions.
0: Clearing condition: When 0 is written in CMF after
reading out RTCSR during CMF = 1.
1: Setting condition: When the condition RTCNT =
RTCOR is satisfied.
Rev. 2.00 May. 08, 2008 Page 225 of 1200
REJ09B0344-0200