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📄 Download Quick Start Guide — SM3 Slim Mechanical Backlit Bluetooth Keyboard · PDF · 0.1 MB

This guide covers setup for the SM3 Slim Mechanical Backlit Bluetooth Keyboard (ST-KSM3LT-EN Light, ST-KSM3DK-EN Dark). The SM3 supports up to 4 total device connections: two simultaneously via Bluetooth (BT1 and BT2), plus one via the included 2.4GHz USB-A wireless receiver, or one via USB-C wired mode. This guide covers powering on the keyboard, all three connection modes, OS selection, LED indicators, backlight behavior, sleep modes, charging, keycap swapping, and resetting the keyboard.

Setup steps:

Step 1: Turn on the SM3 keyboard by moving the switch on the top of the SM3 keyboard to the "on" position.

The power switch is located on the top edge of the SM3 keyboard. Slide it to the ON position. If the SM3 keyboard does not power on, charge it first and try again.

Step 2: Press and hold one of the Bluetooth pairing keys for ~3 seconds until the LED begins to blink.

The Bluetooth 1 (BT1) and Bluetooth 2 (BT2) pairing keys are located in the shortcut key cluster in the top right corner of the keyboard, above the number pad. Hold either BT1 or BT2 for 3 seconds until the LED begins to blink, indicating the SM3 keyboard is in pairing mode.

To pair a second device, repeat the same steps using the other Bluetooth pairing key (BT1 or BT2).

Step 3: Select "Slim SM3 Keyboard" or "Bluetooth Device" in the host device's Bluetooth settings to complete pairing.

On your computer, tablet, or phone, open Bluetooth settings and select "Slim SM3 Keyboard" (it may also appear as "Bluetooth Device") to complete the pairing process. 

Repeat Steps 2–3 using the other Bluetooth pairing key to connect a second Bluetooth device.

Step 4: Connect the included 2.4GHz USB-A wireless receiver to an available USB-A port on your computer, adapter, hub, or dock.

The 2.4GHz USB-A wireless receiver is magnetized to the back of the SM3 keyboard for storage. Remove it and plug it into any available USB-A port on your host device, docking station, or USB-A hub/adapter.

Step 5: Press and hold the USB Receiver key for ~3 seconds to connect the SM3 keyboard to the host device via the 2.4GHz USB-A receiver.

The USB Receiver key is located in the top right shortcut cluster of the keyboard. Hold it for 3 seconds. The backlight will turn on for 3 seconds and then turn off after a successful connection.

Step 6: To use the keyboard in wired mode, connect the included USB-C cable to the keyboard's USB-C port, then press and hold the Wired Mode key for 3 seconds.

In wired mode, the SM3 keyboard will charge if the connected port supports power delivery. Also, the keyboard does not enter sleep mode, and the backlight remains on unless manually turned off.

Step 7: To recharge the keyboard, connect the included USB-C cable to the USB-C port on the SM3 keyboard.

Charge for 2 to 3 hours, or until the LED indicator light turns off.

• The charging LED illuminates blue while the SM3 keyboard is charging.
• The charging LED turns off when the SM3 keyboard is fully charged.
• When the keyboard's power is low, the space bar will slowly flash white, and the backlight will be disabled to conserve battery.

Step 8: Press and hold "FN + Esc" for 1–2 seconds to activate or deactivate the Function key lock (FN Lock).

When FN Lock is enabled, the Esc key will flash every second to indicate the lock is active. Hold FN + Esc again for 1–2 seconds until the Esc key stops flashing to disable FN Lock.

Step 9: Press and hold "FN + O" for 3 seconds to set the keyboard to macOS, iPadOS, or iOS mode.

Image shows the FN key and the O key (labeled "mac") highlighted on the SM3 keyboard.

Important — OS selection is required: After pairing, you must select the correct operating system or the SM3 keyboard may not function properly. Press and hold FN + O for macOS, iPadOS, and iOS. Press and hold FN + P for Windows. The backlight will turn on for 3 seconds and then turn off after a successful OS selection.

Step 10: Press and hold "FN + P" for 3 seconds to set the keyboard to Windows mode.

Image shows the FN key and the P key (labeled "win") highlighted on the SM3 keyboard.

Note for Windows users: When wirelessly pairing with some Windows operating systems, it may be necessary to pair the SM3 keyboard via Control Panel rather than Bluetooth Settings.

Step 11: Num Lock is only active when the SM3 keyboard is in Windows mode and paired with a Windows device.

When Num Lock is enabled, the Num Lock LED will illuminate.

Step 12: When Caps Lock is enabled, the blue Caps Lock LED will illuminate.

Step 13: Sleep mode and backlight behavior on the SM3 keyboard vary by connection type.

• Bluetooth (BT1 or BT2): After 1 minute of inactivity, the backlight turns off to conserve battery. After 30 minutes of inactivity, the SM3 keyboard enters sleep mode. Press any key to wake — the keyboard will automatically reconnect to the paired device.
• 2.4GHz USB Receiver: After 1 minute of inactivity, the backlight turns off. After 10 minutes of inactivity, the SM3 keyboard enters sleep mode. Press any key to wake.
• Wired mode: The SM3 keyboard does not enter sleep mode when connected via USB. The backlight remains on unless turned off manually.

Step 14: When using the SM3 keyboard with Windows, swap the macOS keycaps for the included Windows keycaps (optional).

• Lift both OPT keycaps and both CMD keycaps straight up to remove them.
• Push the included Win and Alt keycaps straight down into place.
• Use a keycap puller when removing keycaps to avoid damage to the switches.
• Note: Only the keycaps are removable and replaceable. The mechanical switches are soldered to the PCB and are not hot-swappable. Do not attempt to remove the switches from the SM3 keyboard.

Step 15: To reset all device connections on the SM3 keyboard, press and hold FN + Del + End for 3 seconds.

• Holding all three keys for 3 seconds resets the keyboard and removes all paired device connections. 
• After the reset, the pairing key will flash continuously until the SM3 keyboard is paired to a host device again.
• Pair your devices again using the steps above.