257
10.2.8
Refresh Timer Control/Status Register (RTCSR)
The refresh timer control/status register (RTCSR) is a 16-bit readable/writable register that
specifies the refresh cycle, whether to generate an interrupt, and the cycle of that interrupt. It is
initialized to H'0000 by a power-on reset, but is not initialized by a manual reset or in standby
mode. Make the RTCOR setting before setting bits CKS2 to CKS0 in RTCSR.
Note:
The method of writing to RTCSR differs from that for general registers to ensure that
RTCSR is not rewritten incorrectly. Use a word transfer instruction to set the upper byte as
B'10100101 and the lower byte as the write data. For details, see section 10.2.12, Cautions
on Accessing Refresh Control Related Registers.
Bit:
15
14
13
12
11
10
9
8
—
—
—
—
—
—
—
—
Initial value:
0
0
0
0
0
0
0
0
R/W:
R
R
R
R
R
R
R
R
Bit:
7
6
5
4
3
2
1
0
CMF
CMIE
CKS2
CKS1
CKS0
OVF
OVIE
LMTS
Initial value:
0
0
0
0
0
0
0
0
R/W:
R/W
R/W
R/W
R/W
R/W
R/W
R/W
R/W
Bits 15 to 8—Reserved: These bits are always read as 0. The write value should always be 0.
Bit 7—Compare Match Flag (CMF): Indicates that the values of RTCNT and RTCOR match.
Bit 7: CMF
Description
0
The values of RTCNT and RTCOR do not match
(Initial value)
Clearing condition: When a refresh is performed after 0 has been written to
CMF and RFSH
=
1 and RMODE
=
0 (to perform a CBR refresh)
1
The values of RTCNT and RTCOR match
Setting condition: RTCNT
=
RTCOR
*
Note:
*
Contents do not change when 1 is written to CMF.
Bit 6—Compare Match Interrupt Enable (CMIE): Enables or disables an interrupt request
caused when CMF in RTCSR is set to 1. Do not set this bit to 1 when using auto-refresh.
Bit 6: CMIE
Description
0
Interrupt request by CMF is disabled
(Initial value)
1
Interrupt request by CMF is enabled
Summary of Contents for SH7709S
Page 2: ...Hitachi SuperH RISC engine SH7709S Hardware Manual ADE 602 250 Rev 1 0 09 21 01 Hitachi Ltd ...
Page 75: ...56 ...
Page 107: ...88 ...
Page 125: ...106 ...
Page 139: ...120 ...
Page 203: ...184 ...
Page 245: ...226 ...
Page 411: ...392 ...
Page 609: ...590 ...
Page 635: ...616 ...
Page 663: ...644 ...
Page 679: ...660 ...