Wireless#

RMK has built-in wireless (BLE) support for nRF52 series, ESP32, and Raspberry Pi Pico W. To use the wireless feature, you need to enable the corresponding feature gate in your Cargo.toml:

rmk = { version = "...", features = [
    "nrf52840_ble", # Enable BLE feature for nRF52840
] }

RMK also provides BLE examples; check out nrf52840_ble, nrf52832_ble, pi_pico_w_ble, and esp32c3_ble for more details.

Since multiple targets are not currently supported by docs.rs, API documentation is not available on docs.rs. Check the examples for usage.

Supported Microcontrollers#

The following is the list of available feature gates (i.e., supported BLE chips):

• nrf52840_ble
• nrf52833_ble
• nrf52832_ble
• nrf52811_ble
• nrf52810_ble
• esp32c3_ble
• esp32c6_ble
• esp32s3_ble
• pico_w_ble (for Raspberry Pi Pico W and Raspberry Pi Pico 2 W)

Nice!nano Support#

RMK has special support for nice!nano, a widely used board for building wireless keyboards.

nice!nano has a built-in bootloader that enables flashing a .uf2 format firmware via USB drive. examples/use_rust/nrf52840_ble/README.md provides instructions for converting RMK firmware to .uf2 format.

You can also refer to the RMK user guide for the instructions.

Multiple-Profile Support#

RMK has multiple BLE profile support. The number of profiles can be set in the [rmk] section in the configuration; the default value is 3.

Vial user keycodes can be configured to operate wireless profiles. Suppose that you have N BLE profiles, then:

• User0 - User(N-1): switch to a specific profile
• UserN: switch to the next profile
• User(N+1): switch to the previous profile
• User(N+2): clear current profile bond info
• User(N+3): switch default output between USB/BLE

Vial also provides a way to customize the displayed keycode, see customKeycodes in this example. If customKeycodes are configured, the User0 ~ User(N+3) will be displayed as BT0, ..., Switch Output.

If you've connected a host to a profile, other devices will not be able to connect to this profile without manually clearing it first.

Wireless Split Support#

RMK also supports wireless split keyboards, where one of the splits acts as the central and the other splits act as peripherals. RMK also supports heterogeneous wireless split configurations; for example, you can use an ESP32S3 as the central and an nRF52 as a peripheral.

RMK provides many split keyboard examples in the examples folder. Check out the examples that end with _split.

For the configuration details, please refer to Configuration/Wireless section.