SH7727 Datasheet, PDF (541/1109 Pages) Renesas Technology Corp – Renesas 32-Bit RISC Microcomputer SuperH RISC engine Family/SH7700 Series

Section 16 Realtime Clock (RTC)
16.2.15 RTC Control Register 1 (RCR1)
The RTC control register 1 (RCR1) is an 8-bit read/write register that contains carry flags and
alarm flags. It also selects whether to generate interrupts for each flag. Avoid the use of read-
modify-write processing for this register because flags are sometimes set after an operand read.
RCR1 is an 8-bit read/write register. The CIE, AIE, and AF bits are initialized by a power-on reset
or manual reset. However, the value of the CF flag is undefined after a power-on reset or manual
reset. It must therefore be initialized without fail before use. This register is not initialized in
standby mode.
Bit: 7
6
CF
—
Initial value: —
0
R/W: R/W
R
5
4
3
2
—
CIE
AIE
—
0
0
0
0
R
R/W R/W
R
1
0
—
AF
0
0
R
R/W
Bit 7—Carry Flag (CF): Status flag that indicates that a carry has occurred. CF is set to 1 when a
carry occurs in R64CNT or RSECCNT. If the count register is read at this time, the value is not
guaranteed; therefore, another read is required.
Bit 7: CF
0
1
Description
No carry in R64CNT or RSECCNT.
Clearing condition: When 0 is written to CF
Setting condition:
Carry occurred in RSECCNT
Read of R64CNT at carry occurrence
When 1 is written to CF
Bits 6, 5, 2, and 1—Reserved: These bits are always read as 0 and should only be written with 0.
Bit 4—Carry Interrupt Enable Flag (CIE): Enables or disables interrupt generation when the
carry flag (CF) is set to 1.
Bit 4: CIE
0
1
Description
A carry interrupt is not generated when the CF flag is set to 1
A carry interrupt is generated when the CF flag is set to 1
(Initial value)
Rev. 5.00 Dec 12, 2005 page 469 of 1034
REJ09B0254-0500