ACE5372

Low Power Real-Time Clock (RTC)

VER 1.2

5

Alarm function and Periodic Interrupt

Alarm Function:

The ACE5372 has an alarm function that outputs an interrupt signal from

⎯ INTRA or ⎯INTRB output pins

to the CPU when the day of the week, hour or minute corresponds to the setting. These two systems of

alarms (ALARM-A, ALARM-B), each may output interrupt signal separately at a specific time. The alarm

may be selectable between on and off for each day of the week, thus allowing outputting alarm everyday

or on a specific day of the week. The ALARM-A is output from the

⎯INTRA pin while the ALARM-B is

output from either the

⎯INTRA or the⎯INTRB pins. Polling is possible separately for each alarm function.

Periodic Interrupt:

The ACE5372 can output periodic interrupt pulses in addition to alarm function from the

⎯INTRA

and

⎯INTRB pins. This frequency may be selected from 2Hz, 1Hz, 1/60Hz, 1/3600Hz and monthly by

controlling register (at lower 3 bits of internal address EH) output selectively.

Output waveform for periodic interrupt may be selected from regular pulse waveform (2Hz and 1Hz) and

waveforms (every second, every minute, every hour and every month) that are appropriate for CPU level

Oscillation Halt Sensing

The oscillation halt sending function uses a register (XSTP bit at internal address FH) to store oscillation

halt information. This function may be used to determine if the ACE 5372 supply power has been booted

from 0V and if it has been backed up. This function is useful for determining if clock data is valid or invalid.

Clock Output

The ACE5372 may output oscillation frequency from INTRB pin. This clock output is set for output by

default, which is set to on or off by setting the register (internal address FH bit CLEN). It can also choose

different crystal oscillator (32.768KHz or 32.000KHz) by setting the register (internal address 7H at bit

XSL), and output clock pulses with two different frequencies.

Registers

1. Clock Counter ( at internal address 0-2H )

*Time digit display ( in BCD code )

Second digits: Range from 00 to 59 and carried to minute digits when incremented from 59 to 00.

Minute digits: Range from 00 to 59 and carried to hour digits when incremented from 59 to 00.

Hour digits: See descriptions on the

⎯12/24 bit (Section 7). Carried to day and day-of-the week digits

when incremented from 11 p.m. to 12 a.m. or 23 to 00.

Any registered imaginary time should be replaced with correct time as carrying to such registered

imaginary time digits from lower-order ones cause the clock counter malfunction.

Second digit register ( at internal address 0H)

D7

D6

D5

D4

D3

D2

D1

D0

Operation

-

S40

S20

S10

S8

S4

S2

S1

Write

0

S40

S20

S10

S8

S4

S2

S1

Read

0

Undefined Undefined Undefined Undefined Undefined Undefined Undefined

Default