bootloader

Uploading firmware through Daisy Bootloader

The chip on board has quite limited flash capacity of 128 kB. To fit larger firmware on Daisy, the Daisy Bootloader exists. Check the documentation to learn about the different bootloader modes and the methods for uploading firmware through it.

In this directory, you'll find an example project that uses the bootloader. The program is copied via DFU to the onboard 8 MB flash storage. When the board starts, the bootloader will then copy the program to SDRAM for faster execution.

This example is made for Daisy Patch SM and assumes you're already familiar with this crate. If you want to flash a different board, update the Cargo.toml accordingly.

Flashing the example

First, install the bootloader on the board. You can use https://flash.daisy.audio/, go to the "Bootloader" tab, select version "v6.2", and flash it. Alternatively you can use the libDaisy project and its Makefile.

Once the bootloader is installed, restart the module and press the BOOT button within the first 2 seconds after startup. The onboard LED should start pulsing, indicating the bootloader is active and waiting.

Now build the example firmware:

cargo objcopy --release -- -O binary target/program.bin

After building, use dfu-util to upload the program. Note the -s parameter, which now points to the beginning of the writable onboard flash, not the internal flash:

dfu-util -a 0 -s 0x90040000:leave -D target/program.bin -d ,0483:df11

The program should now be uploaded, and the onboard LED should be blinking.

Attaching to logs

The bootloader doesn't allow flashing the program using probe-rs, but you can still attach to logs using cargo-embed.

Build the program including INFO-level logs, flash it, and attach to it using an ST-Link programmer:

DEFMT_LOG=info cargo objcopy --release -- -O binary target/program.bin
dfu-util -a 0 -s 0x90040000:leave -D target/program.bin -d ,0483:df11
DEFMT_LOG=info cargo-embed --release

You should now see the log output.

What makes this work

Cargo.toml

The Cargo.toml config is standard, except for the set-vtor feature flag that must be enabled on cortex-m-rt.

memory.x

This file is different from the standard memory.x. The main difference is the region alias replacing FLASH of the default link file with SRAM. The rest of the layout is also slightly adjusted to meet the bootloader’s requirements.

Embed.toml

This file is optional. It makes cargo-embed only read logs without trying to flash the firmware.

Caveats

SRAM

Since the program is uploaded to SRAM and runs from there, your program can't use that memory. Other memory regions are still available, but keep in mind they are either smaller or slower.

Reserved flash

Part of the onboard flash is used to store the firmware. It’s still possible for the firmware to use this flash, but care must be taken when writing to it. The first four 64 kB blocks are reserved, followed by the firmware itself. When using the bootloader in SRAM mode (as in this example), the firmware can take up to 480 kB, so the first 736 kB, or 184 sectors, are occupied and should not be written to.

Credits

Kudos to eulerdisk for explaining how to adjust the linker to work with the bootloader. Thanks to Corvus Prudens and mito3705 from Daisy Discord who shared valuable input on using the Daisy Bootloader with Rust.