Active spoiler controller

Hey guys, not sure how useful this will be to the majority of you, but I made a thing which replaces the standard OEM controller and has a manual up/down button along with standard speed regulated up/down function. I've been using it for a few months without any issues. It uses an arduino to control the old TRL relay diagram so the circuit is fairly simple. It has three functions; manual up, manual down, and automatic. To make it you'll need an arduino nano, a relay module, some stripboard, some 10k resistors, an spdt (on-off-on) switch and lots of wires. You might want to wire it up on a breadboard before you solder everything together to make sure it works.

The automatic function uses the speed signal from the pink wire coming into the engine ECU (someone had already put a bullet connector here in my car so it was the easiest choice). This wire transmits a PWM signal which increases in frequency as the car's speed increases. I think I read that it was 1 pulse for every 4 turns of the transmission sensor thingy but I didn't fancy doing the math so I wrote a small piece of code to log the PWM frequency and drove around with the arduino plugged into the pink wire for a bit so I could make a relatively accurate calibration graph of speed:frequency in MS excel. The raw signal is pretty noisy so I used a rolling average in the code to smooth it which makes activation work a bit better.

Here's a pic of that graph. The flat bits are 40mph, 70mph and 30mph IIRC. I set the ECU to come down at 40mph and go back up at 30mph but this can be customized in the code. I'm not sure the same values will work for every car so you might want to go and test this yourself. For me; 30mph = 17000, 40mph = 13000, 50mph = 10000, 70mph = 7000 approximately though my speedo is a little inaccurate.

http://i.imgur.com/32xoayg.png

The functions are selected by reading the voltage from an SPDT switch as written here.

Here's the circuit diagram:

http://i.imgur.com/fa5vEvS.png

Here's a pic of the assembled circuit:

http://i.imgur.com/OXPpU28.jpg

You could use a much smaller project box than I did and probably lay things out a bit better too. The two relays from the TRL circuit are mounted on the outside of the box so not visible in this pic.

You can download the arduino code from my dropbox.

I'm not going to start making these myself but if anyone has any questions about the code/circuit I'll try and answer them.

Awesome project! Always wondered why no one had done this before!

^As above, really awesome project!

Awesome project! Always wondered why no one had done this before!

They have - 2 members on here have done it before. Latest was Andrewow. Always good to have another though.

Just search for spoiler override

Not while retaining the auto function too I didnt think?

Nice!

Nice work.

In the past I have checked the VSS output on a v160 gearbox and verified that it is 4 pulses per revolution of the output shaft. Here's a chart of the output shaft rotation versus VSS signal for reference:

Andrew had two modules I recall. One was a full loom box for cars that have never had an active spoiler so no ECU, plugs or wiring (like mine). The other piggy backed the active spoiler ECU I think so maybe it did retain the speed activation, but could be overridden?

You've done a great job making a standalone that does it all. Excellent work mate! Hope you have made some space in your PM box