V3025 datasheet(13/17 Pages) EMMICRO

13 / 17 page

V3025

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Reading the Clock

Start

Write clock command

(addr. F1 hex) to the V3025

Read data from the V3025 to

copy the timer parameters from

the reserved clock area to the

RAM.

Write 1/100 sec. address

(20 hex) to the V3025

Read 1/100 sec. data from the

RAM

Write sec. address (21 hex) to

the V3025

Read sec. data from the RAM

Write min. address (22 hex) to

the V3025

Read min. data from the RAM

End

A/D = 0

A/D = 1

A/D = 0

A/D = 1

A/D = 0

A/D = 1

A/D = 0

A/D = 1

[Pin 7 = A/D]

Fig. 12

Setting the Timer (Time Set Lock Bit = 0)

Start

Write 1/100 sec. address

(40 hex) to the V3025

Write 1/100 sec. data to the

RAM

Write sec. address (41 hex) to

the V3025

Write sec. data to the RAM

Write min. address (42 hex) to

the V3025

Write min. data to the RAM

Write hours address (43 hex) to

the V3025

Write hours data to the RAM

End

A/D = 0

A/D = 1

A/D = 0

A/D = 1

A/D = 0

A/D = 1

A/D = 0

A/D = 1

[Pin 7 = A/D]

Write timer command

(addr. F2 hex) to the V3025

A/D = 0

Write F2 hex to the V3025 to

copy the timer parameters from

RAM to the reversed timer area

A/D = 1

Fig. 13

Note

: Commands are only valid as commands when the

/D line is low. Writing F2 hex with the A /D line high,

as in the last box of Fig. 11, serves only to activate the

V3025 write pin which determines the direction of transfer.

Alarm

An alarm date and time may be preset in RAM addresses

30 to 34 hex. The alarm function can be activated by

setting the alarm enable / disable bit (addr. 00 hex, bit 2).

Once enabled the preset alarm time and date are

compared, every internal time update cycle (10 ms), with

the clock parameters in the reserved clock area. When

the clock parameters equal the alarm parameters the

alarm flag (addr. 01 hex, bit 5) is set. If the alarm mask bit

(addr. 01 hex, bit 1) is set, the IRQ pin goes active. The

alarm flag indicates to software the source of the interrupt.

IRQ

will remain active until software acknowledges the

interrupt by clearing the alarm flag.

If the alarm is

enabled, and an alarm address set to FF hex, this

parameters is not compared with the associated clock

parameter. Thus it is possible to achieve a repeat feature

where an alarm occurs every programmed number of

seconds, or seconds and minutes, or seconds, minutes

and hours. The V3025 pulls the open drain IRQ line

active low during standby when an alarm interrupt occurs.

If the 12/24 hour mode is changed then the alarm

hours must be re-initialised.

Note

: The user should ensure that a time lapse of at least

60 microseconds exists between the falling edge of the

IRQ

and the clearing of the alarm flag.

V3025 Datasheet(PDF) 13 Page - EM Microelectronic - MARIN SA

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