This is a great post.

I have an FX35 auto tranny. I want to use the steering wheel switches for something different. I want to use the Vol up/down and Cruise Res/Set as the Manual Shift Mode +/- selector. This would work out pretty well, since the cruise control can't be used in Manual Shift mode anyways.

Can you tell me what voltage Volume up/down and Cruise Res/Set generate? I might talk to some HW folks to see how that the voltage could be converted into the 2 discrete signals (+ / - Manual shift mode). I have the service manual also and looked into this briefly.

Thanks

 

I'm doing this from memory, so I don't remember exactly which current applies to which button, but the volume up, track up, and mode are on one line and the volume down, track down, and power are on another. Each line will read 0v, 1.5v, 3v, or 5v depending on which button is pressed, the current is actually changed, not just the voltage. You can look all this up in the service manual. I'm not sure about the cruise control, it probably works in a similar manner, but it obviously isn't going to the radio which is where I am going to tap into the lines at.

Check out this thread, on mp3car that I started about the steering wheel controls. You may want to post this on that forum, you may get better results.
http://www.mp3car.com/vbulletin/showthread.php?t=23071

Good Luck...


As for progress with just building the control for the radio controls. I'm done building the cable with resistor and diode. I also threw in a 3 way relay to switch between all three cables to and from the radio controls and the computer game port all that I have to do now is put it in the car and write the program to read it. I should have time to finally do this this weekend and post a complete parts list and instructions on how I did it then.

 

IT WORKS!!!!!!!!!!!!!!!

I finished installing the circuit and spent the whole weekend writing the software. The softwares still only about 90% done. It flashes buttons on the screen rather then sending key presses right now, but it shows the data being recieved better then I anticipated and after calibration is flawless.

Heres the final circuit I used. The only real part to this circuit is the resistors and diodes. All that these do is prevent the joystick axis from reading 0v when no button is pressed. The different size resistors determine what voltage above 0 will be sent when no button is pushed. After alot of playing around I found that a resistor around 500 ohms works best.

You can get all these parts at your local radio shack, but buying them online is much cheaper.

To construct this circuit you will need 2 510 ohm resistors:
http://www.allelectronics.com/matrix...Resistors.html

2 Diodes:
http://www.allelectronics.com/cgi-bi...001&type=store

A 3 way relay connected to a switch of some sort of switch between the radio wires and joystick wires:
http://www.allelectronics.com/cgi-bi...632&type=store

Optionally, if you have a long distance to go to get to the game port, some 3 wire cable to run from the joystick port to the circuit:
http://www.allelectronics.com/cgi-bi...S22&type=store

You will also need the 15 pin connector end that plugs into the game port to splice into. If you dont have an old joystick you want to splice up, you can get one of these:
http://www.compgeeks.com/details.asp...=41811&cat=CBL

If you don't have a game port you can get a game port to USB adaptor, I know they make these, just don't know any place off hand that sells them.

All this should cost you < $10 plus shipping.

Since this is such a simple circuit to build, I will not be selling them as I initially said. You should just need a soldering iron and some connectors to connect everything together, Just follow the circuit diagram, you can also get connectors real cheap at allelectronics.com if you dont have any. The only hard part is taking everything apart and the fact that you have to solder 11 wires onto 1 relay. You will have to completly cut the 3 wires leading into the radio and splice them into the 3 way relay. I cut them then put butt connectors on both ends if the circut is taken out they can be connected back to each other to restore just the original functionality. Make sure you go by the colors of the wires in the circuit diagram below, I remember there being some discrepincies in the pin #s. I'll post pics of my actual circuit soon. I'll also post the software within the next week or so.





212503-Joystick Wire Diagram.GIF

 

Picture showing the cabling. The cable that connects between the resistors, diodes and the game port is not shown, nor is the power supply cables going from a switch to the relay.



212517-Joystick Pic.JPG

 

For the number of the pinouts on the joystick port listed in the circuit diagram, just go to this page.
http://www.epanorama.net/documents/j..._circuits.html

There is also a fake joystick circuit on that page that may be helpful for testing purposes.

To test the joystick circuit once it is built and hooked up, on windows XP, goto control panel / game controllers click on the button to create a custom controller then create a controller with 2 axises and 0 buttons, click ok. Add the custom joystick you just created if its not there already, if its connected, the status should read OK. Select the joystick then click on properties, goto the other tab and click calibrate. When it asked to be centered, don't press any of the steering wheel buttons, when it asks to move the joystick around, press all the joystick buttons. To confirm that the different buttons are working properly, click on show raw data on the page that your suppose to press all the buttons on. The raw data for each button should be a different range, there will be some noise in the axis data so 2 buttons could overlap momentarily, the program I am writing will account for this so don't worry. As a baseline, I get around 21-22 for 1 button 23-24 for another, i think 26-28 for the third and >30 when no button is being pressed.

 

great job with this.

Before your initial post, I was thinking of doing something like this with USB, but the analog nature of the steering wheel controls turned me away.

I should have remembered that the x and y-axis for a game port is analog.. It's been a long time since I used gamepads/joysticks on a computer.

I may eventually do this install... and since it's only two wires, a switch to toggle both wires at once shouldn't be too hard. Just getting wires for the game port to the trunk is going to be a pain. That gamepad->usb adapter is intriguing though, as I have a usb hub sitting up front.

Thanks for your research in this subject

2004 Twlight Blue/Willow 6mt Coupe.
Bel Vector 985 Hardwired.
Grounding Kit.
Next Project: Carputer.

 

oops didn't realize what you said about the relay, so forget what I said about the switch.

I have a question about your schematic though..

At the bottom, you have the pin called "Ground / Power (Yellow)". Where is that going to exactly?

I understand the rest of the circuit, but i don't quite get where you'd want to switch between 5V and the radio harness's GND wire.

Thanks

2004 Twlight Blue/Willow 6mt Coupe.
Bel Vector 985 Hardwired.
Grounding Kit.
Next Project: Carputer.

 

Ok, I probably didn't do the best job of explianing hooking it up to the car. There are 3 wires total you need cut coming from the steering wheel controls and going into the back of radio. There is a red wire used for 3 of the buttons (Mode, Seek Up, Vol Up), a Green wire used for the other 3 buttons (Power, Seek Down, Vol Down), and a Yellow one which is called remote control ground in the service manual, I never actually tested the line to see if it was actually a ground and not just called that, but I have to assume it is and this is how the radio works, so that wire has to be a ground if you want the radio controls to work normally.

For the joystick circuit, you need to supply 5v power that will regulated to the proper current / voltage by the resistors inside the steering wheel controls and output back out to the X and Y axis of the game port. Since the radio works in reverse and supplies a ground instead of power, you have to swap out the ground line for the 5v power line supplied by the game port. This is why I called the line "Ground / Power" since when the relay is switched to the radio a ground needs to be supplied to the steering wheel controls, but when it is switched to the game port, a 5v power line is supplied.

Also, this may have not been clear from the wiring diagram, but all the wires on the side of the relay with only a single pin go to the steering wheel controls. ("Remote control A", "Remote Control B", and "Ground / Power") are the half of the cut steering wheel control wires that go to the steering wheel controls, the ones labeled "Radio Harness..." are the other half of the wires going to the radio harness. I showed 2 relays in the circuit diagram cause I didn't have a diagram for a single 3 way relay, which is what I used for the real thing, although you can use two, theres no reason to.

 

ah now I understand, thanks for the great explaination.

And unfortunately now I see why I can't use a double pole switch.

And I don't want a relay with the switch part connected to "computer power switch" only because I'd want to do radio stuff with the steering wheel controls while the computer is still on (navigation, for instance), so a single pole switch AND a relay may be in order for me, unless I can find a triple pole double toggle out there... doubt it.

Thanks again for the informative post.

2004 Twlight Blue/Willow 6mt Coupe.
Bel Vector 985 Hardwired.
Grounding Kit.
Next Project: Carputer.

 

wizawuza,

Heres a 4PDT relay mayhaps this will do for you.

http://www.allelectronics.com/cgi-bi...-12&type=store

 

Heh, I already have tons of switches and a 3 pole relay, guess I'll just use another switch and the 3 way relay instead of a 4 way. Thanks for the suggestion though.

Anyways, how's the progress with the software coming along? What functions do you plan to control with the steering wheel anyways? I'd guess the seek for next/prev track, volume for volume, mode for some sort of Alt-Tab? And what about power? It'd be neat to have that turn off the computer, but, I don't think that can turn the thing back on. Please correct me if I'm wrong though.

Thanks.

2004 Twlight Blue/Willow 6mt Coupe.
Bel Vector 985 Hardwired.
Grounding Kit.
Next Project: Carputer.

 

The software will just send key presses to the active window only. It will send pretty much any key plus ctrl, alt, and shift combinations of those letters, it should do Alt+Tab fine. It will also do repeating at a user defined interval and accelerating repeat. I will not be building in any other functions to map to like volume control or shutting down the computer.

Currently on my carputer the key presses are sent to my interface app that processes them as next prev / track, volume up/down, "listen" for voice commands, and backspace to go to the previous part of the program.

On my interface app sending Alt+F4 shows a timed shutdown screen that allows cancelling if a cancel button is pressed in time. I'll probably eventually map the power button to this once I get the bugs worked out. There would, however, still be no way to turn the PC back on without some more hardware. You'll have to use a voltmeter to confirm this, but I *think* the steering wheel power button gives off the most voltage (I think a little above 4v) when connected to the computer game port. If I am right about this, you could just hook up the trigger of a 5v relay to the line that the power button is connected to and hook the pole part to the power jumper on your motherboard. The relay should only get enough voltage when the power button is down so In theory it just might be an easy want to do what you want.

I'm still having some filtering issues where a single axis value that maps to a button is read from the joystick port even though no joystick button is pressed. This would seem to be just a limitation from the poor quality of the analog to digital converter on the joystick port, but should be overcome with some more filtering. I'm currently trying to perfect this filtering (Only indicating the button down if X number of an axis value is read consecutively).

I'll post at least a beta up this weekend to test with. I'm running the software in my car now and its working perfectly if you just map the volume and track buttons, buts some issues yet mapping all 6 at once. I'll post a full setup package with the final executable within the next 2 weeks.

 

Heres a BETA of the software program to turn steering wheel button presses into key presses on the computer. It works by mapping a range on a joystick access to a particular key press. You first have to map out the ranges to the buttons that they correspond to. Once an access is mapped buttons can be assigned to it.

Before running this program you will need to have the MFC 7.1 runtime libraries and the latest version of directX installed. I'll eventually provide an installer for this program that will include the MFC libraries. You will also need to have added and calibrated a joystick in the control panel using the instructions I gave in a previous post.

This is a tray app. After running the app, right click on the joystick icon in the tray and select configure, select the joystick you calibarated for the steering wheel controls from the drop down list, then double click an axis you want to configure. Follow the instructions in the wizard that appears to map the axis ranges to buttons. Once your down with this you can test your buttons by going to "Bind Keys to Joystick". A green box shoudl appear next to the name of the steering wheel button your pressing when you press it. Press the button to the left of the button name to map a key to it.

If your getting undesirable results, you can mess around with the filtering settings by right clicking on the tray app and selecting options.

This is only a BETA, I'm going to be completely rewriting the button capture portion cause it doesn't take into consideration overlapping of buttons but it should run fine mapping just the up and down buttons and be good enough for testing.

Let me know what problems you have with the program.

Download the program here:
http://filebox.vt.edu/users/cholbroo/TrayApp.zip

On a separate note, for those without a game port, it's probably possible to build the joystick circuit just by ripping apart a USB joystick and tapping into one of the analog to digital converters on one of the axises.

 

The final software is coming soon, possibly this weekend... I have to solve a power issue with my carputer first so I can test it, but it in theory should be pretty much done.