Filter
Top Products
Rev. 5.00, 09/03, page 419 of 760
13.2.15 RTC Control Register 1 (RCR1)
The RTC control register 1 (RCR1) is an 8-bit readable/writable register that affects carry flags
and alarm flags. It also selects whether to generate interrupts for each flag. Because flags are
sometimes set after an operand read, do not use this register in read-modify-write processing.
RCR1 is initialized to H'00 by a power-on reset or a manual reset. In a manual reset, all bits are
initialized to H'00 except for the CF flag, which is undefined. When using the CF flag, it must be
initialized beforehand. This register is not initialized in standby mode.
Bit:76543210
CF — — CIE AIE — — AF
Initial value:00000000
R/W: R/W R R R/W R/W R R R/W
Bit 7—Carry Flag (CF): Status flag that indicates that a carry has occurred. Setting CF to 1
indicates reading of a counter register value has occurred when (1) the second counter is carried or
(2) the 64-Hz counter is carried. A count register value read at this time cannot be guaranteed;
another read is required.
Bit 7: CF Description
0 No count up of R64CNT or RSECCNT
Clearing condition: When 0 is written to CF (Initial value)
1 Count up of R64CNT or RSECCNT
Setting condition: When 1 is written to CF
Bits 6, 5, 2, and 1—Reserved: These bits are always read as 0. The write value should always be
0.
Bit 4—Carry Interrupt Enable Flag (CIE): When the carry flag (CF) is set to 1, the CIE bit
enables interrupts.
Bit 4: CIE Description
0 A carry interrupt is not generated when the CF flag is set to 1 (Initial value)
1 A carry interrupt is generated when the CF flag is set to 1