#Storage

RMK's storage system provides persistent data storage for keyboard settings, keymaps, and system configuration. It uses your microcontroller's internal flash memory to save changes between power cycles.

The [storage] section in keyboard.toml configures RMK's storage.

#Configuration Options

[storage]
# Enable/disable storage feature (default: true). Must match the `storage` Cargo feature of rmk
enabled = true
# Number of flash sectors to allocate. Defaults to 8 when a [dfu] section is present, either here or
# in the chip default (nRF52840, nice!nano, RP2040 and Pico W ship one); otherwise 2 unless the chip
# default sets a value
num_sectors = 2
# Storage start address (default: 0 = auto-allocate from end; on nRF BLE builds without DFU,
# 0 means 0x60000)
start_addr = 0x00000000
# Clear all storage data on boot, including keymap, BLE bonds, etc
clear_storage = false
# Clear only layout/keymap data, preserve BLE bonds
clear_layout = false

let storage_config = StorageConfig {
    start_addr: 0x70000,    // Custom start address
    num_sectors: 2,         // Number of sectors
    ..Default::default()
};

let rmk_config = RmkConfig {
    storage_config,
    ..Default::default()
};

enabled must agree with the storage Cargo feature of the rmk crate in both directions: enabled = false requires disabling the feature (for example with default-features = false), and a build without the feature requires enabled = false. The build fails otherwise.

#Storage and DFU

When using DFU (dfu_rp / dfu_nrf), the storage partition is placed after the DFU download slot, determined by the rmk-memory.x linker script. In this mode:

• start_addr is ignored — RMK automatically places storage at the address defined in rmk-memory.x (__bootloader_storage_start).
• The default num_sectors is 8 (32 KB, matching rmk-boot's default storage area). You can override num_sectors to use fewer sectors, but cannot exceed the allocated area.

If you change the storage size in rmk-boot's build.rs, rebuild the bootloader and regenerate rmk-memory.x. All partition addresses recalculate automatically.