Casio module 5657: user manual and setup (GST-B400)

The module number is engraved on the case back of the watch. It usually sits in a small rectangle next to the water resistance markings. If it says 5657, this guide applies to your watch. The module defines the functions and the setup procedure, regardless of the model's commercial name.

Which watches use module 5657

Module 5657 is a combination G-SHOCK module with hands and a digital display. The hands can be moved aside so the display beneath them can be read. The watch is charged by light and connects to a phone through the G-SHOCK Connected app. At Classic this module is found in the following model:

• GST-B400-1AER – Casio G-Shock GST-B400-1AER

Buttons and modes

The manual labels the buttons with letters, for example (A) and (D). The function of each button depends on the selected mode. The watch has Timekeeping Mode, World Time, Alarm, Stopwatch and Countdown Timer. Switching between modes is described in the section "Navigating Between Modes". In Timekeeping Mode you can change the content of the digital display. There is also a function for moving the hands aside when they cover the display.

How to set the time and date

The manual describes two ways to set the time: automatically via the phone and manually with the watch buttons.

1. Install the G-SHOCK Connected app on a supported phone. The list of supported phones is in the section "Supported Phones".
2. Pair the watch with the phone by following the steps in the section "Connecting with a Phone".
3. While connected, the watch corrects the time automatically. This function is called Auto Time Adjustment.
4. Select your home city from the section "Changing the Home City". The summer time setting is in "Summer Time Setting".
5. Without a phone, the time is set manually as described in "Using Watch Operations to Adjust the Time".
6. The date format is changed from "Changing the Date Display Format". The language of the day of the week is selected from "Specifying the Day of the Week Language".

If the hands do not match the digital time, use the hand correction. It is described in the section "Hand Alignment Adjustment". It can be done from the watch or through the G-SHOCK Connected app.

World Time

The watch shows the time in another city of your choice. The city is set from the watch or through the app. The city table is at the end of the manual. There is also a table of summer time by region. The Home Time and World Time can be swapped. This is useful when travelling in another time zone.

Alarm and hourly time signal

The module has a digital alarm. Its settings are made from the watch or through the app. Separately, an hourly time signal can be turned on, which sounds every hour on the hour. Turning off the alarm and the hourly time signal is described in a separate section.

Stopwatch

The Stopwatch measures elapsed time, split times and lap times.

• Button (D) starts and stops the measurement.
• Button (A) records a split time or a lap.
• The split time is shown with the [SPL] indicator for about eight seconds.
• For a lap, the time alternates with the lap number for about eight seconds.

During the first hour the time is shown to 1/100 of a second. After the first hour it is shown in seconds.

Countdown Timer

The start time of the timer is set in steps of one second. The maximum is 60 minutes. If a countdown is already running, first reset the timer to the start time. To set it, enter Countdown Timer Mode and hold button (A) for at least two seconds. Release the button when the minutes start to flash. The setting can also be made through the app.

Reminders and Phone Finder

Reminders are created through the G-SHOCK Connected app. The content of each reminder can be checked on the watch. The Phone Finder function helps you find your phone while it is connected to the watch.

Charging and battery level

The watch charges when the face is exposed to light. The charge level can be checked on the watch. There is a power saving function, whose settings are configured separately. Details on battery care are in the section "Battery".

Illumination

The face can be illuminated for reading in the dark. How to turn it on is described in the section "Viewing the Face in the Dark".

Other settings

The button operation tone can be turned on and off. The watch can record the current location using the TIME & PLACE function. All settings are returned to the factory defaults from a separate section. The manual also describes how to disconnect from the phone and how to cancel pairing when changing phones.

Water resistance and care

Check the marking on the back of the watch before using it in water. Do not press the buttons while the watch is wet or under water. After sea water, rinse the watch with clean water. The gaskets are replaced periodically, about once every two to three years. Battery replacement is done only at a service centre with the proper tools. Avoid very high and very low temperatures, as well as contact with solvents and cosmetics.

The original Casio manual (PDF)

Casio module 5657 manual (PDF, English) is the official Casio document with the full steps for every function.

Casio at Classic. Browse all Casio watches at Classic and the manuals for all Casio modules. You can see the watches in person at Boutique CLASSIC on Knyaz Boris I 32 and at Mall Varna.