FAQ

Where is my built firmware?

By default, the built firmware is at target/<TARGET>/<MODE> folder, where <TARGET> is your microcontroller's target and <MODE> is debug or release, depending on your build mode.

The firmware's name is your project name in Cargo.toml. It's actually an elf file, but without file extension.

I want `hex`/`bin`/`uf2` file, how can I get it?

By default, Rust compiler generates elf file in target folder. There're a little extra steps for generating hex, bin or uf2 file.

hex/bin: To generate hex/bin file, you need cargo-binutils. You can use

cargo install cargo-binutils
rustup component add llvm-tools

to install it. Then, you can use the following command to generate hex or bin firmware:

# Generate .bin file
cargo objcopy --release -- -O binary rmk.bin
# Generate .hex file
cargo objcopy --release -- -O ihex rmk.hex

uf2: RMK provides cargo-make config for all examples to generate uf2 file automatically. Check Makefile.toml files in the example folders. The following command can be used to generate uf2 firmware:
```
# Install cargo-make
cargo install --force cargo-make

# Generate uf2
cargo make uf2 --release
```
This script requires you have python command available in your commandline. Some platforms have python3 command only, you can change python in Makefile.toml to python3 in this case.

I can see a `RMK Start` log, but nothing else

First you need to check the RCC config of your board, make sure that the USB's clock is enabled and set to 48MHZ. For example, if you're using stm32f1, you can set the RCC as the following:

#![allow(unused)]
fn main() {
// If you're using a keyboard.toml
#[rmk_keyboard]
mod keyboard {
    use embassy_stm32::{time::Hertz, Config};

    #[Override(chip_config)]
    fn config() -> Config {
        let mut config = Config::default();
        config.rcc.hse = Some(Hertz(8_000_000));
        config.rcc.sys_ck = Some(Hertz(48_000_000));
        config.rcc.pclk1 = Some(Hertz(24_000_000)); 
        config
    }
}
}

If the keyboard still doesn't work, enabling full logging trace at .cargo/config.toml:

[env]
DEFMT_LOG = "trace"

run cargo clean and then cargo run --release. Open an issue with the detailed logs.

rust-lld: error: section will not fit in region 'FLASH': overflowed by x bytes

This is because your MCU's flash is too small. Try building in release mode: cargo build --release. If the error still there, follow our binary size optimization doc to reduce your code size.

I see ERROR: Storage is full error in the log

By default, RMK uses only 2 sectors of your microcontroller's internal flash. You may get the following error if 2 sectors is not big enough to store all your keymaps:

ERROR Storage is full
└─ rmk::storage::print_sequential_storage_err @ /Users/haobogu/Projects/keyboard/rmk/rmk/src/storage.rs:577 
ERROR Got none when reading keymap from storage at (layer,col,row)=(1,5,8)
└─ rmk::storage::{impl#2}::read_keymap::{async_fn#0} @ /Users/haobogu/Projects/keyboard/rmk/rmk/src/storage.rs:460 
ERROR Keymap reading aborted!
└─ rmk::keymap::{impl#0}::new_from_storage::{async_fn#0} @ /Users/haobogu/Projects/keyboard/rmk/rmk/src/keymap.rs:38

If you have more sectors available in your internal flash, you can increase num_sectors in [storage] section of your keyboard.toml, or change storage_config in your RmkConfig if you're using Rust API.

panicked at embassy-executor: task arena is full.

The current embassy requires manually setting of the task arena size. By default, RMK set's it to 32768 in all examples:

# Cargo.toml
embassy-executor = { version = "0.6", features = [
    "defmt",
    "arch-cortex-m",
    "task-arena-size-32768",
    "executor-thread",
    "integrated-timers",
] }

If you got ERROR panicked at 'embassy-executor: task arena is full. error after flashing to your MCU, that means that you should increase your embassy's task arena. Embassy has a series cargo features to do this, for example, changing task arena size to 65536:

# Cargo.toml
embassy-executor = { version = "0.6", features = [
    "defmt",
    "arch-cortex-m",
-   "task-arena-size-32768",
+   "task-arena-size-65536",
    "executor-thread",
    "integrated-timers",
] }

In the latest git version of embassy, task arena size could be calculated automatically, but it requires nightly version of Rust.

If you're comfortable with nightly Rust, you can enable nightly feature of embassy-executor and remove task-arena-size-* feature.

RMK breaks my bootloader

By default RMK uses last 2 sectors as the storage. If your bootloader is placed there too, RMK will erase it. To avoid it, you can change start_addr in [storage] section of your keyboard.toml, or change storage_config in your RmkConfig if you're using Rust API.

RMK Documentation