RX − 8564 LC

13.1.3. Clock counter ( Reg −

02 [h] to 04 [h] )

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Address [h]

 

Function

 

bit 7

bit 6

bit 5

bit 4

bit 3

bit 2

bit 1

bit 0

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

02

 

Seconds

 

VL

40

20

10

8

4

2

1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

03

 

Minutes

 

⋅

40

20

10

8

4

2

1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

04

 

Hours

 

⋅

⋅

20

10

8

4

2

1

 

 

 

 

 

 

 

 

 

 

 

 

 

•The clock counter counts seconds, minutes, and hours.

•The data format is BCD format. For example, when the "seconds" register value is "0101 1001" it indicates 59 seconds.

∗When overwriting time data, we recommend setting "1" to the STOP bit to stop the clock before overwriting. (This prevents unintentional carry operations from occurring while overwriting data.)

∗Note with caution that writing non-existent time data may interfere with normal operation of the clock counter.

1)[ Seconds ] register ( Reg − 02 [h] ) This counter counts seconds.

Count values are updated as: 00 seconds, 01 second, 02 to 59 seconds, 00 seconds, 01 second, etc. in that order.

2)[ Minutes ] register ( Reg − 03 [h] )This counter counts minutes.

Count values are updated as: 00 minutes, 01 minute, 02 to 59 minutes, 00 minutes, 01 minute, etc. in that order.

3) [ Hours ] register ( Reg − 04 [h] )The [Hours] counter uses a 24-hour clock.

Count values are updated as: 00 hours, 01 hour, 02 to 23 hours, 00 hours, 01 hour, etc. in that order.

4) VL bit ( Voltage Low Flag )This is a flag bit that retains the result when detecting low voltage.

When the power source's voltage drops below VLOW[V]*, this flag is set to 1.

If this bit's value is "1" when read, this RTC's data is ignored, in which case all registers should be initialized before being used.

(1)A "1" is set to this VL flag during initial power-on (from 0 V).

Since the value of other registers is undefined at this time, be sure to reset all registers before using them.

(2)When recovering from backup mode, read this VL flag, and if its value is "1" be sure to initialize the registers before using them.

(3)When initializing, be sure to clear this VL flag to zero to prepare for the next voltage detection.

(4)This VL flag was designed to provide a voltage drop warning after the voltage of the backup battery or other devices has gradually dropped, and it is not designed to respond to sharp fluctuations in voltage due to power supply chatter, etc.

(1) VL=”1”

(2) VL=”0”

(3) VL=”1”

VDD

 

 

VLOW

 

 

GND

 

GND=0 V

 

 

(1)VL="1" as result of initial supply of power

(2)When the power supply is low but voltage not dropping to VLOW, VL remains at "0" with no change

(3)When the power supply is low and voltage dropping below VLOW, VL becomes "1".

∗The value of the VL bit in (2) and (3) need to be zero cleared in (1).

(5)This VL flag is cleared via a write operation regardless of data. Be sure to read this flag's value before writing to this register.

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ETM12E-01