Joystick app

[nxdefiant]

Hi,

I'm currently working on a simple Joystick App using the accelerometer as stick input, but it does need an extra hid descriptor. If you are interested in adding the app there are basically two options:

1. Extend the HID descriptor in boot0.js with the joystick one
2. Execute the NRF.sendHIDReport() call in the application itself, downside: The application will only work when settings.HID is disabled.

Any preference?

[gfwilliams]

Hmm. That's a hard one. We could do something like:

  if (s.HID) {
    if (s.HID=="joystick") Bangle.HID = E.toUint8Array(atob("..."));
    else Bangle.HID = E.toUint8Array(atob("..."));
    NRF.setServices({}, {uart:true, hid:Bangle.HID});
  }

Then we could make the type of HID device optional - and apps and then easily check if it's set to the right one?

Otherwise I guess we could store the actual descriptor in settings if it's non-standard, which could be more flexible...

[nxdefiant]

After some more testing I would actually prefer option #1, since the Bluetooth hosts does not always seem to react well to the descriptor change: Sometimes I had to to restart the host for the new service to get recognized.

Also extending the descriptor should not be a problem to the two exiting profiles. Obviously it hardly scales with every new Bluetooth app..The next person wants to add a mouse descriptor...

Otherwise I guess we could store the actual descriptor in settings if it's non-standard, which could be more flexible...

Flexible yes, but I think harder to manage. We would need some kind of interface for the user to select which services he wants out of (keyboard, multimedia, joystick) and build the descriptor accordingly.

[gfwilliams]

Ok then, sounds like a plan. Do you have the descriptor that you'd like me to add?

[nxdefiant]

Sure, this one:

0x05, 0x01,       // Usage Page (Generic Desktop)
0x09, 0x04,       // Usage (Joystick)
0xA1, 0x01,       // Collection (Application)
	0x85, 0x03,        //   Report ID (3)
	0x09, 0x01,       // Usage (Pointer)
	0xA1, 0x00,       // Collection (Physical)

		// Buttons
		0x05, 0x09,       // Usage Page (Buttons)
		0x19, 0x01,       // Usage Minimum (1)
		0x29, 0x05,       // Usage Maximum (5)
		0x15, 0x00,       // Logical Minimum (0)
		0x25, 0x01,       // Logical Maximum (1)
		0x95, 0x05,       // Report Count (5)
		0x75, 0x01,       // Report Size (1)
		0x81, 0x02,       // Input (Data, Variable, Absolute)

		// padding bits
		0x95, 0x03,       // Report Count (3)
		0x75, 0x01,       // Report Size (1)
		0x81, 0x03,       // Input (Constant)

		// Stick
		0x05, 0x01,       // Usage Page (Generic Desktop)
		0x09, 0x30,       // Usage (X)
		0x09, 0x31,       // Usage (Y)
		0x15, 0x81,       // Logical Minimum (-127)
		0x25, 0x7f,       // Logical Maximum (127)
		0x75, 0x08,       // Report Size (8)
		0x95, 0x02,       // Report Count (2)
		0x81, 0x02,       // Input (Data, Variable, Absolute)
	0xC0,              // End Collection (Physical)
0xC0              // End Collection (Application)

So the complete descriptor becomes in base64:
Bangle.HID = E.toUint8Array(atob("BQEJBqEBhQIFBxngKecVACUBdQGVCIEClQF1CIEBlQV1AQUIGQEpBZEClQF1A5EBlQZ1CBUAJXMFBxkAKXOBAAkFFQAm/wB1CJUCsQLABQwJAaEBhQEVACUBdQGVAQm1gQIJtoECCbeBAgm4gQIJzYECCeKBAgnpgQIJ6oECwAUBCQShAYUDCQGhAAUJGQEpBRUAJQGVBXUBgQKVA3UBgQMFAQkwCTEVgSV/dQiVAoECwMA="));

[gfwilliams]

Not sure if the base64 is right... the length of that is 179, but the array above it is only 52?

I'll stick the actual array contents in

[nxdefiant]

Thats the complete base64 descriptor including the other two keyboard and multimedia.

[gfwilliams]

Ahh, wow. I was thinking we'd just make it change to be just a Joystick?

I just pushed some changes in 517c35a that should make this work nicely for you (I hope!)

[nxdefiant]

One minor change please. if it is "just a joystick" please exclude the report id in the hid descriptor. The text in hid_info.txt already has it excluded, but not the base64 in boot0.js, it should become:

'BQEJBKEBCQGhAAUJGQEpBRUAJQGVBXUBgQKVA3UBgQMFAQkwCTEVgSV/dQiVAoECwMA='

Keyboard works fine with the unpatched Linux/bluez, but you should be aware that on Linux I had to restart bluetoothd everytime I switched the HID setting. On Android I had to disable and enable bluetooth. This might produce a lot "it does not work" bug reports because of the required bt restart on the host. This is the full test matrix:

App	\ 	Setting:	Keyboard + Media	Keyboard	Joystick
Keyboard->Linux			ok			ok		-
Media->Linux			ok			-		-
Joystick->Linux			-			-		ok
Keyboard->Linux(unpatched)	error(1)		ok		-
Joystick->Linux(unpatched)	-			-		error(2)
Media->Linux(unpatched)		error(1)		-		-
Keyboard->Android		ok			ok		-
Media->Android			ok			-		-

error(1) = expected by the bluez report id problem/bug
error(2) = Needs removal of report id in joystick descriptor to work

[gfwilliams]

The text in hid_info.txt already has it excluded, but not the base64 in boot0.js

That's odd - I generated the base64 right from it - but sure, I'll stick the new one in.

Thanks for doing that testing. Honestly I find myself restarting bluetoothd pretty often on Linux anyway, so I don't think this is really anything new :)

[nxdefiant]

Looks good, I'm closing this ticket, thank you.