> ## Documentation Index
> Fetch the complete documentation index at: https://docs.minimalmacropad.com/llms.txt
> Use this file to discover all available pages before exploring further.

# MinimalPad Hardware: Keys, Encoder, and Connections

> Learn about MinimalPad's 16-key grid, rotary encoder, USB-C port, battery connector, RGB underglow, hot-swap sockets, and power behaviour.

MinimalPad is built around a 4×4 grid of hot-swap mechanical switches, a rotary encoder, and a wireless-capable nRF52840 controller — all in a compact low-profile form factor. This page explains what each part of the hardware does and how it relates to configuration in MinimalPad Studio.

## The 16-key grid

MinimalPad has 16 Kailh Choc low-profile mechanical key positions arranged in a 4×4 grid. Every key is independently programmable — each one can send a different action on each layer.

Keys use Kailh Choc hot-swap sockets, meaning you can pull out and swap switches without soldering. Any Kailh Choc low-profile switch is compatible.

To see what each key is currently assigned to, open [MinimalPad Studio](https://studio.minimalmacropad.com/) and connect your device. Studio shows a live map of every key on every layer.

## Layers

Layers let the same 16 physical keys do different things depending on which layer is active — similar to how Shift changes a key's output, but for entire sets of actions. You can view, add, remove, and rename layers in Studio.

For example:

* **Layer 0 (default):** your everyday shortcuts
* **Layer 1:** media controls
* **Layer 2:** application-specific actions

Assign a key on any layer to activate another layer — momentarily, toggled, or as a tap/hold action. The current layer assignments are always visible in Studio.

## Rotary encoder

The rotary encoder sits at the top of the pad and has two distinct inputs:

* **Rotate clockwise / counter-clockwise** — these actions are defined in the firmware and appear as read-only in Studio. You cannot change them through the browser configurator; changing them requires editing the firmware.
* **Press the encoder** — pressing the encoder shaft down acts like a regular key press. This action is fully configurable in Studio, just like any of the 16 grid keys.

<Note>
  The encoder's rotation behaviour is firmware-defined and locked in Studio — you'll see it displayed but won't be able to reassign it without reflashing. The encoder press, however, is a normal configurable key position.
</Note>

## USB-C port

The USB-C port on MinimalPad serves three purposes:

1. **Power** — charge the battery or run the device directly from USB power
2. **Wired connection** — use MinimalPad as a wired keyboard and connect to Studio over USB/Serial
3. **Firmware flashing** — put the device into bootloader mode to drag-and-drop a new firmware file

<Warning>
  Use a **data-capable** USB-C cable. Charge-only cables will not establish a connection with Studio and cannot be used for firmware flashing.
</Warning>

## Battery connector

The JST connector on the PCB accepts a 3.7V LiPo battery for wireless operation. A battery is not included — see [Before You Begin](/getting-started/before-you-begin) for specifications and polarity notes before purchasing one.

MinimalPad charges the battery through the USB-C port. You can use the device while it charges.

## Power behaviour

| State                 | What happens                                                            |
| --------------------- | ----------------------------------------------------------------------- |
| Plugged in via USB    | Powers on immediately; USB takes priority over battery                  |
| Battery only          | Powers on when you press a key or move the encoder                      |
| Idle for \~30 seconds | RGB LEDs turn off; device enters light sleep; Bluetooth stays connected |
| Idle for \~10 minutes | Device enters deep sleep; press any key to wake                         |

ZMK's power management keeps battery consumption very low. You can expect weeks or months of battery life depending on usage patterns and battery capacity.

## RGB underglow

MinimalPad has 16 WS2812 RGB LEDs mounted under the PCB, creating an underglow effect. The LEDs are controlled through key assignments in Studio — assign any key to an RGB action such as Toggle, Brightness Up/Down, Hue change, or cycle through effects.

RGB is off by default when the device wakes from sleep. Assign an RGB Toggle key to turn it back on quickly.

## Hot-swap sockets

All 16 key positions use Kailh Choc hot-swap sockets. To swap a switch:

1. Use a switch puller or gently pry the switch upward from both sides
2. Press the new switch straight down until both pins seat fully into the socket

No soldering is required. Use only Kailh Choc low-profile switches — standard MX-height switches are not compatible with the low-profile sockets or keycaps.

## Controller

MinimalPad is built around the nRF52840 chip, housed in either a Nice!Nano V2 or an NRF52840 clone module depending on your configuration. Both run ZMK firmware and support all features — Bluetooth, USB, battery charging, and Studio configuration — identically.