editing usb_joystic.h to include more analogue pins

[lil_head]

I'm working on making a 'joystick' which has many throttle-like controls. ie. analogue inputs.
The joystick example that i have looked at is the one that come with the teensyduino. I realised this is limited to 6 axes(also stated on the website http://www.pjrc.com/teensy/td_joystick.html)

I am trying to work out if I can increase the amount of axes by editing the usb_joystick.h to include more axes. Is this functionality limited by windows, by the example provided or by the device itself?

Below is an extract of the file and I curious if I can modify the sliderLeft/sliderRight to slider1, slider2 etc then add more sliders (slider3, slider4...)
If so how do I modifiy the rest of the data (Coloured text) for each new axes I add?

I'm using a teensy3 on win7 using teensyduino.

void X(unsigned int val) {
		if (val > 1023) val = 1023;
		[COLOR="#FF0000"]usb_joystick_data[1] = (usb_joystick_data[1] & 0xFFFFC00F) | (val << 4);[/COLOR]
		if (!manual_mode) usb_joystick_send();
	}
	void Y(unsigned int val) {
		if (val > 1023) val = 1023;
		[COLOR="#FF0000"]usb_joystick_data[1] = (usb_joystick_data[1] & 0xFF003FFF) | (val << 14);[/COLOR]
		if (!manual_mode) usb_joystick_send();
	}
	void position(unsigned int x, unsigned int y) {
		if (x > 1023) x = 1023;
		if (y > 1023) y = 1023;
		usb_joystick_data[1] = (usb_joystick_data[1] & 0xFFF00000)
			| (x << 4) | (y << 14);
		if (!manual_mode) usb_joystick_send();
	}
	void Z(unsigned int val) {
		if (val > 1023) val = 1023;
		[COLOR="#FF0000"]usb_joystick_data[1] = (usb_joystick_data[1] & 0x00FFFFFF) | (val << 24);
		usb_joystick_data[2] = (usb_joystick_data[2] & 0xFFFFFFFC) | (val >> 8);[/COLOR]
		if (!manual_mode) usb_joystick_send();
	}
	void Zrotate(unsigned int val) {
		if (val > 1023) val = 1023;
		[COLOR="#FF0000"]usb_joystick_data[2] = (usb_joystick_data[2] & 0xFFFFF003) | (val << 2);[/COLOR]
		if (!manual_mode) usb_joystick_send();
	}
	void sliderLeft(unsigned int val) {
		if (val > 1023) val = 1023;
		[COLOR="#FF0000"]usb_joystick_data[2] = (usb_joystick_data[2] & 0xFFC00FFF) | (val << 12);[/COLOR]
		if (!manual_mode) usb_joystick_send();
	}
	void sliderRight(unsigned int val) {
		if (val > 1023) val = 1023;
		[COLOR="#FF0000"]usb_joystick_data[2] = (usb_joystick_data[2] & 0x003FFFFF) | (val << 22);[/COLOR]
		if (!manual_mode) usb_joystick_send();
	}
	void slider(unsigned int val) {
		if (val > 1023) val = 1023;
		usb_joystick_data[2] = (usb_joystick_data[2] & 0x00000FFF)
[COLOR="#FF0000"]			| (val << 12) | (val << 22);[/COLOR]
		if (!manual_mode) usb_joystick_send();

Any advice would be appreciated.

Cheers

lil

 

[PaulStoffregen]

The first step is editing the USB descriptors. This looks like Teensy 3.0, so they'll be in usb_desc.c. The descriptor data is what tells your PC how many axes and buttons and other features are present. You need to get this right first, then modify the actual data transmitted to match whatever format the descriptor specified.

 

[lil_head]

Thanks Paul. I'll start there and post my results here for anyone interested. But I'm a beginner so might be a while.