Legacy Maple DFU boot loader support

[fpistm]

This PR enable only the Legacy Maple DFU boot loader support, STM32 HID bootloader from @Serasidis will come in an other PR. We currently discuss/work on it.

Should supersede #415

From @BennehBoy (#415)

This PR enables the use of the STM32 HID Bootloader 2.1 for Generic F103 & Generic F4 variants

Tested on Bluepill, Blackpill (using BP menu option), & Black407VET6.

Limitations:

* boards.txt glue probably needs to be a bit more elegant --> done in #525

* F1 boards must use the latest 2K HID bootloader -> https://github.com/Serasidis/STM32_HID_Bootloader  (hid_flash tool will warn if an older version is installed)

Usage:

First apply this PR to your STM32 tools -> stm32duino/Arduino_Tools#33. --> replaced by stm32duino/Arduino_Tools#35

HID:
Select your variant in the boards menu
Set the upload method to "HID Bootloader 3.0 (0x0800)" for F1 or "HID Bootloader 3.0 (0x4000)" for F4
Ensure that "USB Interface (if available):" is set to "CDC Full Speed" (required for DTR toggling)

DFU:
The PR applies the magic word & byte code recognition to USB_CDC_IF.cpp which also enables STM32Duino Bootloader 2.0 to work. Also included is DISC pin handling for Maple Mini. This is the same logic used in Roger Clarke's core and in STM32GENERIC
Select your variant in the boards menu
Set the upload method to "Maple DFU Bootloader 2.0" or "Maple DFU Bootloader original" depending on the BL installed.
Ensure that "USB support (if available):" is set to either CDC option (required for DTR toggling)

Require stm32duino/Arduino_Tools#35

DFU bootloader 2.0 tested under windows and linux.

Any help to test are welcome.

Cc @BennehBoy , @Serasidis

Fix #411

[BennehBoy]

@fpistm what should I do with the other PR? Don't want to delete mine if it will remove the entire thread, I guess it may be useful historically?

[fpistm]

It will be only closed. History will be kept.

[BennehBoy]

Just tested against Maple Mini clone, and the same forced hardware reset requirement persists that I was attempting to track down with no luck... ie, upload works fine but the board does not do it's eventual toggle back to the newly flashed code - not sure if this is disc pin or what. (tested BL 2.0 on Blackpill and the board recycles fine). This on Windows 10

I'll attempt some HID loads on blue/blackpill next.

[BennehBoy]

HID tested and working with BlackPill 👍

[BennehBoy]

OK, so I just deleted a previous post - I couldn't get the maple mini behaviour to repeat so had thought it was due to the previously flashed CDC handling being overwritten on first reflash.... 5 flashes in a row with no issue. Then it started again, so it looks like there's potentially something iffy in the disc pin handling OR these clones don't like the code (this issue first arose when you refactored the disc pin handling btw, the very crude code I had included seemed to work without issue but was admittedly v ugly).

[Serasidis]

A few days ago I started working on adapting HID Bootloader (HID-BL) to the Official STM Core. I know @BennehBoy is working on it, but I have not seen the source code (any link is welcome).
So, I started from scratch adding HID-BL to this Core.

There is a new feature in the Arduino-IDE 1.8.9 Pluggable Discovery I'm working on.
This feature adds an extra Port menu that includes HIDs in addition to the available serial ports.
This is very useful if someone wants to restart the STM32 on the bootloader, but the built-in USB is configured as a HID device or any other USB device such as MIDI.

[fpistm]

@BennehBoy, unfortunately, I didn't see this behavior.

@Serasidis , I saw that on your forum. Seems promising. Do not hesitate to share and ask support.
Also any feedback on this PR is welcome about HID BL support ;)

[BennehBoy]

@Serasidis I'm not really doing anything with this at the moment, the dtr/magic word handling code was a direct copy of your STM32GENERIC code. Feel free to augment in whatever way. I didn't make any changes to the bootloader code itself at all.

[neilbalch]

I would love to help test this, but I use PlatformIO. I'm not exactly sure how to merge this PR with the tools already implemented there. Does anyone here know how that would work? I could always ask around in the PlatformIO community if the answer is no.

[BennehBoy]

Can't help you there, I've avoided PlatformIO because the tool config just seems so obfuscated.

[fpistm]

@neilbalch unfortunately no.

[neilbalch]

👍 🎊