Help a newbie with the joystick sensors and PCB?

Hello guys,

I've been interested in building my own HOTAS module since I unboxed my HOTAS Warthog and found out the throttle levers were made of plastic. I'm pretty handy with CAD, so considered building my control system, but now I am having trouble figuring out the electronics.

I thought these sensors looked like they might work.
http://www.digikey.ca/product-search/en?vendor=0&keywords=HRS100SSAB090
The datasheet is at the link as well, but I don't think it says how accurate or repeatable the pots are or what kind of error I can expect.

I looked at the I-PAC and the BU0836X, as well as the KEUSB108 from Hagstrom Electronics, as well as the Basic FLUSB, but the I-PAC doesn't specify whether it's analogue or digital, and all the rest only seem to have analogue inputs with 12-bit resolution.

I'm at a loss for how to get 16-bit resolution like the resolution Thrustmaster claims on the Warthog. Are there any commercial, off-the-shelf USB Joystick PCBs that can make use of the extra resolution, or should I look into buying a Teensy or an Arduino? (Since I know little to nothing about how to program, this might not be the best course for me) Or will 12 bit and 16 bit resolution make no difference with the sensors I've selected, and should I look for better sensors?

Thank you very much, any advice is appreciated.

And this using a 12 bit sensor:

12 bit Angular Resolution - 10 bit Angular Thermal Accuracy

Why not use "MagRez" sensor - no, you dont find this in sales web sites, is need assemble one.

http://simhq.com/forum/ubbthreads.php/topics/4053568/Re:_MMJoy_-_Build_your_own_USB#Post4053568

Or buy MaRS from VKB - in this case is need specify analog output to use with the mentioned USB Controllers (Bu0836...)
All these mentioned controllers work in analog mode - 3 wires for connect potentiometer/sensor.

http://www.vkb-flightsimcontrols.com/zakaz/index_z.php

BTW - Their USB controller (NJoy32) is more advanced that mentioned ones (has ability to record macros on EEPROM), in this case order MaRS in digital mode (less external interference = spikes).

Hey Sokol1,

The Warthog's sensor isn't really 16-bit resolution?!

Yikes! I did not realize that at all!

You really can't feel 16 bit resolution anyway. The joystick mechanics aren't fine enough to transmit the small changes and we're talking about 0.003mm of movement. Anything above 12 bit, it's doubtful anyone could take advantage of the resolution.
Hempstead wrote a good article on sensor resolution. http://www.hempstick.org/download/articles/OnResolution.pdf

Whew, thanks. That's good to know, I am glad to hear it. If 12 bit is as good as I need, looks like I'll have everything I'll need to get started, if I can use an off-the-shelf PCB, and just connect it to the buttons I need.

To be fair to TM, the sensor they use, MLX90333, has a front end ADC of 14bit. The output DAC is 12bit (the front and ADC senses the Hall Effect voltage into digital values, and DSP processes it, filter, scaling, and then compute the X,Y, Z, etc), then, if you program the chip to output analog signal, then the 12 bit DAC is used to output rail-to-rail 0 to 5V.

However, AFAIK, Warthog uses the SPI digital mode, so it could potentially have 14 bit resolution output. It is possible to use oversampling to increase resolution, but MLX90333 does not have enough sampling rate to do this, as it requires 4^2 times more sampling rate to boost 14bit to 16bit, and MLX90333 only has about 1000KHz sampling rate. So, if they oversample it to 16bit, Warthog's max USB report rate would be less than 62.5Hz. That would be horrible because 14bit resolution is sufficient and sacrificing sampling rate for resolution you can't use is not a smart compromise.

So, my guess is that because MLX90333's SPI report is 2byte per axis (16bit), TM claims it 16bit. But internally, MLX90333 probably just takes the 14bit and shift left two to make it 16bit for output.

Case in point, T16000M uses the exact same MLX90333 chip, but it claims the followings.



That's about 14-bit.