[Team USB] - AKA The dirty work

[taylor]

This is the development thread for Team USB, which will be bringing up USB support on the Flutter platform. This is a tough job but is critical to Flutter's usability, so Team USB is kind of Flutter's All-Star team.

Background:
Flutter automatically presents a programming interface over USB when erased, but we currently do not have USB support in Arduino that would allow us to use the USB for communications. Most of Arduino's code for the Due works for Flutter because most of the peripherals are the same between the chips. However the USB peripheral in the Due chip is a USB On The Go port, which means it offers limited hosting capability. The USB peripheral in Flutter is a USB device port, so it uses different code. Arduino has not written this code, so we get to!

TODO: Bring up USB support in Arduino for Flutter's SAM3s processor.

NOTE: I have not posted the necessary files, yet, but this will be done asap (likely tomorrow).

[systech]

Hi everyone... I think I'm on this team. Could be interesting. I did USB development in 1.x and it was a lot of register poking to get things happy. Hopefully Taylor has some good guidelines. Name is Mark.

[taylor]

Yeah, I have some code to use as a starting point as well as some JTAG shields I should send out to you guys (I need to order them).

I will share everything as soon as I can. Polishing up the main code repository for release and then I can start sharing stuff related to the USB code. I have brought up one ARM-based USB device in the past so I won't be totally useless. There's some good talent on this team too.

[taylor]

Okay! The changes to the code this week are looking great, I need to get you all the USB example code I was going to use to get this going!

There's 3 main pieces of code involved - 2 examples and the existing USB On The Go code in the Flutter Arduino Codebase.
The two examples are the best codesets I could find that appear to support USB on the SAM3S:
www.flutterwireless.com/files/usb_examples.zip
Unfortunately, Arduino seems to be using a different set of support libraries, so the naming isn't all consistent. We need to mostly write out this file:

flutterwireless/ArduinoCodebase/blob/master/hardware/arduino/sam/system/libsam/source/udp.c

Also the name udp.c comes from the fact that it is a USB Device Port, but this name conflicts with udp.c in the Arduino library, which is used to handle the UDP protocol over IP. We should probably change udp.c to usbdp.c or similar.

Also note that all of the Arduino-based code is in that "hardware" folder. Nothing related to the port is outside of that as the rest deals with the IDE. I should include this information in the docs if I don't say that in the readme.

[taylor]

I should note that the work done on this USB code will be immensely useful, not just for Flutter but to other Free Hardware projects that want to use the SAM3S line of CPUs with Arduino. For example I plan on making a very nice brushless motor driver that has its own ARM chip, and I'm going to use the same CPU flutter uses. It will have serial for daisy chaining these controllers to Flutter, but it will also have USB so you can take any brushless motor and drive it from a PC easily. This will be super useful for testing new motors, etc.

There's a whole collection of CPUs in this family that only have the USB Device Port and not the USB On The Go that the Due uses.

And of course, Flutter will be lame without proper USB support!

[systech]

Ok. I had a rough somewhat busy week but will try to dive back into this some this weekend and more next week.

[turoart]

Hi, is there any advance on this subject? maybe some beta code to try?

[taylor]

Yes, I've been given some beta code and I hear enumeration is partially working. I will update this post with links to all those files probably monday, as I do want you guys to be able to help. But it sounds like we're in the home stretch!