FEATHER-M0-Bootloader-UF2

UF2 Bootloader Details

Les cartes Adafruit Express et Gemma/Trinket M0 embarque un bootloader amélioré qui facilité (plus que jamais) le flashage de différents code sur le microcontrôleur. Ce bootloader facilite la transition entre Microsoft MakeCode, CircuitPython et Arduino.

A la place d'avoir besoin d'un pilote ou d'un programme séparé pour flasher la carte (disons, bossac, jlink ou avrdude), il est simplement possible de glisser des fichiers sur un lecteur amovible.

Le format du fichier est un peu spécial. A cause des 'incompatibilités des systèmes d'exploitation', il n'est pas possible de transférer un fichier binaire ou hex (selon les tests d'Adafruit, ce n'est pas cross-platform compatible). A la place, le format de fichier contient des informations complémentaires pour aider le bootloader à savoir où les données doivent être placées. Ce format est appelé UF2 (USB Flashing Format, format de flashage usb). Microsoft MakeCode génère de l'UF2 pour le flashage et les releases de CircuitPython sont également disponible en UF2. Vous pouvez même créer votre propre UF2 depuis un fichier binaire en utilisant uf2tool, disponible ici.

Le bootloader est également compatible BOSSA, il peut donc être utilisé avec Arduino IDE qui attend un bootloader BOSSA sur les carte à base d'ATSAMD.

Pour plus d'information sur UF2, vous pouvez lire de nombreuses informations sur le blog MakeCode, puis lire les spécifications du format UF2. Voyez également le fork Adafruit de l'UF2 de Microsoft pour samd (dépôt GitHub) pour le code source et les releases des bootloaders pre-compilés.

Activer le mode Booloader

The first step to loading new code onto your board is triggering the bootloader. It is easily done by double tapping the reset button. Once the bootloader is active you will see the small red LED fade in and out and a new drive will appear on your computer with a name ending in BOOT. For example, feathers show up as FEATHERBOOT, while the new CircuitPlayground shows up as CPLAYBOOT, Trinket M0 will show up as TRINKETBOOT, and Gemma M0 will show up as GEMMABOOT

Furthermore, when the bootloader is active, it will change the color of one or more onboard neopixels to indicate the connection status, red for disconnected and green for connected. If the board is plugged in but still showing that its disconnected, try a different USB cable. Some cables only provide power with no communication.

For example, here is a Feather M0 Express running a colorful Neopixel swirl. When the reset button is double clicked (about half second between each click) the NeoPixel will stay green to let you know the bootloader is active. When the reset button is clicked once, the 'user program' (NeoPixel color swirl) restarts.

Crédit: AdaFruit Industries www.adafruit.com

If the bootloader couldn't start, you will get a red NeoPixel LED.

That could mean that your USB cable is no good, it isn't connected to a computer, or maybe the drivers could not enumerate. Try a new USB cable first. Then try another port on your computer!

Crédit: AdaFruit Industries www.adafruit.com

Once the bootloader is running, check your computer. You should see a USB Disk drive...

Crédit: AdaFruit Industries www.adafruit.com

Once the bootloader is successfully connected you can open the drive and browse the virtual filesystem. This isn't the same filesystem as you use with CircuitPython or Arduino. It should have three files:

• CURRENT.UF2 - The current contents of the microcontroller flash.
• INDEX.HTM - Links to Microsoft MakeCode.
• INFO_UF2.TXT - Includes bootloader version info. Please include it on bug reports.

Crédit: AdaFruit Industries www.adafruit.com

Utiliser le Bootloader Mass Storage

To flash something new, simply drag any UF2 onto the drive. After the file is finished copying, the bootloader will automatically restart. This usually causes a warning about an unsafe eject of the drive. However, its not a problem. The bootloader knows when everything is copied successfully.

Crédit: AdaFruit Industries www.adafruit.com

You may get an alert from the OS that the file is being copied without it's properties. You can just click Yes .

Crédit: AdaFruit Industries www.adafruit.com

You may also get get a complaint that the drive was ejected without warning. Don't worry about this. The drive only ejects once the bootloader has verified and completed the process of writing the new code

Utiliser le Bootloader BOSSA

As mentioned before, the bootloader is also compatible with BOSSA, which is the standard method of updating boards when in the Arduino IDE. It is a command-line tool that can be used in any operating system. We won't cover the full use of the bossac tool, suffice to say it can do quite a bit! More information is available at ShumaTech.

Pilotes pour Windows 7

If you are running Windows 7 (or, goodness, something earlier?) You will need a Serial Port driver file. Windows 10 users do not need this so skip this step.

You can download our full driver package here:

Télécharger le dernier installeur de pilote Adafruit

Download and run the installer. We recommend just selecting all the serial port drivers available (no harm to do so) and installing them.

Crédit: AdaFruit Industries www.adafruit.com

Verifying Serial Port in Device Manager

If you're running Windows, its a good idea to verify the device showed up. Open your Device Manager from the control panel and look under Ports (COM & LPT) for a device called Feather M0 or Circuit Playground or whatever!

Crédit: AdaFruit Industries www.adafruit.com

If you see something like this, it means you did not install the drivers. Go back and try again, then remove and re-plug the USB cable for your board

Crédit: AdaFruit Industries www.adafruit.com

Running bossac on the command line

If you are using the Arduino IDE, this step is not required. But sometimes you want to read/write custom binary files, say for loading CircuitPython or your own code. We recommend using bossac v 1.7.0 (or greater), which has been tested. The Arduino branch is most recommended.

You can download the latest builds here. The mingw32 version is for Windows, apple-darwin for Mac OSX and various linux options for Linux. Once downloaded, extract the files from the zip and open the command line to the directory with bossac

For example here's the command line you probably want to run:

bossac -e -w -v -R ~/Downloads/adafruit-circuitpython-feather_m0_express-0.9.3.bin

This will -erase the chip, -write the given file, -verify the write and -Reset the board. After reset, CircuitPython should be running. Express boards may cause a warning of an early eject of a USB drive but just ignore it. Nothing important was being written to the drive. A hard power-reset is also recommended after bossac, just in case.

Crédit: AdaFruit Industries www.adafruit.com

Faire une mise-à-jour du bootloader

The UF2 bootloader is a new bootloader, and while we've done a ton of testing, it may contain bugs. Usually these bugs effect reliability rather than fully preventing the bootloader from working. If the bootloader is flaky then you can try updating the bootloader itself to potentially improve reliability.

Updating the bootloader is as easy as flashing CircuitPython, Arduino or MakeCode. Simply enter the bootloader as above and then drag the update bootloader uf2 file below. This uf2 contains a program which will unlock the bootloader section, update the bootloader, and re-lock it. It will overwrite your existing code such as CircuitPython or Arduino so make sure everything is backed up!

After the file is copied over, the bootloader will be updated and appear again. The INFO_UF2.TXT file should show the newer version number inside.

For example:

UF2 Bootloader v1.20.0 SFHR
Model: Adafruit Feather M0
Board-ID: SAMD21G18A-Feather-v0

Lastly, reload your code from Arduino or MakeCode or flash the latest CircuitPython core.

The latest updaters for various boards:

Circuit Playground Express v1.23 update-bootloader.uf2

Feather M0 Express v1.23 update-bootloader.uf2

Metro M0 Express v1.23 update-bootloader.uf2

Gemma M0 v1.23 update-bootloader.uf2

Trinket M0 v1.23 update-bootloader.uf2

Eliminer les popups Windows

If you do a lot of development on Windows with the UF2 bootloader, you may get annoyed by the constant "Hey you inserted a drive what do you want to do" pop-ups.

Toutes les images ci-dessous sont créditées à Adafruit Industries - All images here under are credited to Adafruit Industries

	Go to the Control Panel. Click on the Hardware and Sound header
	Click on the Autoplay header
	Uncheck the box at the top, labeled Use Autoplay for all devices

Faire votre propre UF2

Making your own UF2 is easy! All you need is a .bin file of a program you wish to flash and the Python conversion script. Make sure that your program was compiled to start at 0x2000 (8k) because the bootloader takes the first 8k. CircuitPython's linker script is an example on how to do that.

Once you have a .bin file, you simply need to run the Python conversion script over it. Here is an example from the directory with uf2conv.py:

uf2conv.py -c -o build-circuitplayground_express/revg.uf2 build-circuitplayground_express/revg.bin

This will produce a revg.uf2 file in the same directory as the source revg.bin. The uf2 can then be flashed in the same way as above.

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Source: Adafruit Feather M0 Express - Designed for CircuitPython créé par LadyAda, Tony DiCola, Scorr Shawcroft, Dan Halbert pour AdaFruit Industries. Crédit AdaFruit Industries

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