CF5762AB0

NIPPON PRECISION CIRCUITS INC.—6

Chattering Elimination

Power-ON Initialization

When power is applied, the following reset functions

take place.

I

Clock movement motor outputs (O1, O2)

After the oscillator starts, each output is activated

with O1 being LOW and O2 being HIGH.

I

Reset (RESET)

After power is applied, a 62.5ms reset pulse is out-

put. If, however, RESET is HIGH when power is

applied, the corresponding reset state is recog-

nized as-is.

I

Melody trigger (MT)

If MT is HIGH when power is applied, melody

output stops. Melody output starts when MT goes

LOW and then goes HIGH again.

I

Time information (S1 to S4)

The time data is reset to a zero state not represent-

ing any hour in the range 1 to 12 o’clock, and the

inputs are not read until the next hourly signal

input.

I

Melody switching function (SEL1, SEL2)

When power is applied, the input states are reset

and then immediately read in.

I

Melody stop at night (AMI, PMI)

When power is applied, the PM flag is set to LOW

(AM setting) and then, immediately, the input

states are read in. If at this time both AMI and PMI

are HIGH, then the PM flag stays set to LOW.

Input

Description

S1 to S4, CDS, WSEL

No chattering elimination function

MT, RESET

If the input goes HIGH and continues for 2 or more 16Hz cycles, then the input is recognized, otherwise it is ignored.

If the input goes LOW, it is sampled at 16Hz.

AMI, PMI

If the input changes state and continues for 2 or more 16Hz cycles, then the input is recognized, otherwise it is ignored.

SEL1, SEL2

The inputs are sampled periodically at 16Hz. If either SEL1 or SEL2 changes state, the state is held for 62.5ms and then

the state of both SEL1 and SEL2 are read. If either SEL1 or SEL2 changes state during this interval, a further interval of

62.5ms is added before reading the input states (see figure 2).

Figure 2. SEL1, SEL2 read timing

16Hz

SEL1

SEL2

62.5ms 62.5ms

62.5ms 62.5ms 62.5ms

Read hold pulse

Status read clock