Watch Catalog

Casio module 5638

Quartz module. 5638 is the number engraved on the caseback of these watches, and Casio files its operation manual under it. 2 watches in the catalog run on it.

How to operate module 5638

Short steps in our words. The buttons are lettered as in Casio's operation guide, where each task's page is given.

Set the time and date

  1. In the Timekeeping Mode, hold B for at least two seconds and let go when the Home City name shows (SET shows first).
  2. Press C until the setting you want flashes. The order is: Home City, summer time, 12/24-hour format, seconds, hour, minutes, date display format, year, month, day, day of the week language, schedule notification tone, button tone, auto light, light duration, Airplane Mode, then back to the Home City.
  3. On the seconds, press D to reset them to 00.
  4. On the other settings, press A or D to change them.
  5. Press B to leave the setting screen.

Good to know

With a phone paired in CASIO WATCHES, the watch sets its time by itself while it is connected. To set it from the phone now, keep the phone within one meter and hold D for at least two seconds in the Timekeeping Mode: CNCT flashes, then OK shows and the time is set.

Set the time on the watch only when it cannot connect with a phone. After you set the time, the Home City or swap the cities by hand, auto time adjustment does not work for 24 hours.

Setting the time by hand switches off the schedule timer; connect with the phone to sync the time and use it again.

Resetting the seconds while they count 30 to 59 adds one minute.

12/24-hour format: hold B until the Home City shows, press C twice (12H or 24H flashes), press D to switch, then press B.

In any mode, hold C for at least two seconds to go back to the Timekeeping Mode.

From Casio's guide, page 5

Summer time

  1. In the Timekeeping Mode, hold B for at least two seconds and let go when the Home City name shows.
  2. Press C: the summer time setting flashes.
  3. Press D to step through AUTO (switches between standard time and summer time by itself), OFF (always standard time) and ON (always summer time).
  4. Press B to leave the setting screen.

Good to know

Every city is set to AUTO at the factory, which in many cases needs no change.

With a phone connected, the Home City summer time can also be changed in CASIO WATCHES.

For the World Time city: in the World Time Mode, press D to show the city, hold B for at least two seconds until AUTO flashes, press D to pick AUTO, OFF or ON, then press B. This cannot be done while UTC is picked.

The DST indicator shows while the watch shows summer time.

From Casio's guide, page 5

Home City

  1. In the Timekeeping Mode, hold B for at least two seconds and let go when the Home City name shows.
  2. Press A or D until your city shows.
  3. Press C: the summer time setting flashes; press D to change it if needed.
  4. Press B to leave the setting screen.

Good to know

The cities and their time offsets are in the City Table in the manual.

To swap the Home City time and the World Time, hold A for at least two seconds in the World Time Mode. This can also be done in CASIO WATCHES; auto time adjustment then does not work for 24 hours.

CASIO WATCHES can set the World Time city from about 300 cities. Picking a different city on the watch afterwards deletes the app's city from the watch.

From Casio's guide, page 4

Set an alarm

  1. Press C until the Alarm Mode shows; the mode hand points to AL.
  2. Press D to pick the alarm, AL1 to AL5.
  3. Hold B for at least two seconds and let go when the hour flashes. ON shows below the alarm time.
  4. Press A or D to set the hour. In 12-hour format, P marks p.m.
  5. Press C: the minutes flash. Press A or D to set them.
  6. Press B to leave the setting screen. Check that ON shows; if it shows OFF, press B to switch the alarm on.
  7. Hold C for at least two seconds to go back to the Timekeeping Mode.

Good to know

The alarm sounds for 10 seconds; press any button to stop it. It does not sound when the battery is low.

In the Alarm Mode, press B to switch the shown alarm between ON and OFF. ALM shows while any alarm is on.

Hourly time signal: in the Alarm Mode, press D until SIG shows, then press B to switch it on or off.

Alarms can also be set in the CASIO WATCHES app.

From Casio's guide, page 12

Hand alignment

  1. In the Timekeeping Mode, hold B for at least five seconds and let go when 00 flashes (H-SET shows after about 3.5 seconds, then SUB).
  2. If the mode hand is not on 00, press A or D to put it there.
  3. Press C. If the hour and minute hands are not at 12 o'clock, press A or D to put them there.
  4. Press B to leave the setting screen.

Good to know

Strong magnetism or impact can put the hands out of line with the digital time.

The buttons move the minute hand; the hour hand follows it.

With a phone connected, hand alignment can also be done in CASIO WATCHES.

From Casio's guide, page 14

Light

  1. Press A to light the face.
  2. Auto light: in the Timekeeping Mode, hold B for at least two seconds until the Home City shows, press C 13 times (AUTO shows), press D to switch ON or OFF, then press B.
  3. Light duration: hold B until the Home City shows, press C 14 times (LIGHT shows), press D to pick 1 (1.5 seconds) or 3 (three seconds), then press B.

Good to know

With auto light on, the face lights when you angle the watch 40 degrees or more towards you. LT shows while it is on, and it switches itself off after about six hours.

The light goes off when an alarm starts to sound.

From Casio's guide, page 3

Button tone

  1. In the Timekeeping Mode, hold B for at least two seconds and let go when the Home City name shows.
  2. Press C 12 times: KEY♪ or MUTE flashes.
  3. Press D to pick KEY♪ (button tone on) or MUTE (button tone off).
  4. Press B to leave the setting screen.

Good to know

Alarm and timer tones still sound with the button tone muted.

The button tone can also be set in CASIO WATCHES.

From Casio's guide, page 15

Stopwatch

  1. Press C until the Stopwatch Mode shows, after the Timekeeping Mode.
  2. Press D to start, D to stop, and D again to carry on.
  3. Lap time: while it runs, press B; the time of that lap shows for eight seconds and is stored.
  4. When it is stopped, press B to reset it to zero.
  5. Hold C for at least two seconds to go back to the Timekeeping Mode.

Good to know

It counts up to 24 hours, in 1/1000 seconds for the first hour and in 1/10 seconds after that. The mode hand shows the lap time seconds.

Up to 200 lap times are stored; the oldest is deleted to make room. They can be sent to CASIO WATCHES and viewed there.

From Casio's guide, page 10

Countdown timer

  1. Press C until the Timer Mode shows, after the Stopwatch Mode.
  2. Hold B for at least two seconds and let go when the hours flash.
  3. Press A or D to set the hours, press C, set the minutes the same way, press C again, then set the seconds.
  4. Press B to leave the setting screen.
  5. Press D to start, D to pause and D to carry on; when paused, press B to reset it to the start time.
  6. Hold C for at least two seconds to go back to the Timekeeping Mode.

Good to know

The start time goes up to 24 hours in 1-second steps.

At zero a beeper sounds for 10 seconds; press any button to stop it. It does not sound when the battery is low.

The timer can also be set in CASIO WATCHES.

From Casio's guide, page 11

Factory reset

  1. In the Timekeeping Mode, hold B for at least two seconds and let go when the Home City name shows.
  2. Press C three times: the seconds flash.
  3. Hold A for at least five seconds and let go when RESET stops flashing.

Good to know

This returns the watch settings, stopwatch, timer and alarms to their factory defaults.

It also deletes the pairing information, so the watch is no longer paired with the phone.

From Casio's guide, page 16

Module 5638 specs

Type
quartz
Power
Approx. battery life: 2 years on CR2016 · other watches that take CR2016
Accuracy
±15 seconds per month (with no mobile link function)
Functions
World time, Stopwatch, Timer, Alarm/hourly time signal, Light, Light color, Calendar, Mute feature, 12/24-hour format, Date/month display swapping, Day display, Hand shift feature, Flight mode, Schedule beeper on/off
Manual
Casio's operation guide for module 5638

Watches with the 5638