TinyUF2 Bootloader

This repo is cross-platform UF2 Bootloader projects for MCUs based on TinyUSB

.
├── lib               # Sources from 3rd party such as tinyusb, mcu drivers ...
├── ports             # Port/family specific sources
│   ├── esp32s2       
│   │   └── boards/   # Board specific sources
│   │   └── Makefile  # Makefile for this port
│   └── mimxrt10xx         
├── src               # Cross-platform bootloader sources files

Features

TODO more docs later

Support ESP32-S2, iMXRT10xx, LPC55xx, STM32F3, STM32F4
Self update with update file in uf2 format
Indicator: LED, RGB
Debug log with uart/swd
Double tap to enter DFU, reboot to DFU and quick reboot from application

Build and Flash

Requirements

GCC cross compiler and Make

Compile

Firstly clone this repo and its submodules with

$ git clone --recurse-submodules https://github.com/adafruit/tinyuf2

To build this for a specific board, we need to change current directory to its port folder

$ cd ports/stm32f4

Then compile with make BOARD=[board_name] all, for example

make BOARD=feather_stm32f405_express all

Flash

flash target will use the default on-board debugger (jlink/cmsisdap/stlink/dfu) to flash the binary, please install those support software in advance. Some board use bootloader/DFU via serial which is required to pass to make command

$ make BOARD=feather_stm32f405_express flash

If you use an external debugger, there is flash-jlink, flash-stlink, flash-pyocd which are mostly like to work out of the box for most of the supported board.

Debug

To compile for debugging add DEBUG=1, this will mostly change the compiler optimization

$ make BOARD=feather_stm32f405_express DEBUG=1 all

Log

Should you have an issue running example and/or submitting an bug report. You could enable TinyUSB built-in debug logging with optional LOG=. LOG=1 will print out only message from bootloader project, while LOG=2 print more information with TinyUSB stack information events as well (note: it is quite a bit). LOG=3 or higher is not used yet.

$ make BOARD=feather_stm32f405_express LOG=1 all

Logger

By default log message is printed via on-board UART which is slow and take lots of CPU time comparing to USB speed. If your board support on-board/external debugger, it would be more efficient to use it for logging. There are 2 protocols:

LOGGER=rtt: use Segger RTT protocol
- Cons: requires jlink as the debugger.
- Pros: work with most if not all MCUs
- Software viewer is JLink RTT Viewer/Client/Logger which is bundled with JLink driver package.
LOGGER=swo: Use dedicated SWO pin of ARM Cortex SWD debug header.
- Cons: only work with ARM Cortex MCUs minus M0
- Pros: should be compatible with more debugger that support SWO.
- Software viewer should be provided along with your debugger driver.

$ make BOARD=feather_stm32f405_express LOG=2 LOGGER=rtt all
$ make BOARD=feather_stm32f405_express LOG=2 LOGGER=swo all

henrygab/tinyuf2