Megasquirt Traction Control
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Schrödinger's cat - so which one am I ???

Couple of pics of the trigger wheel arrangement on goldie. What you can't really see in the rear pic is the series of bolts fitted to the outer edge of the drum. As you guys are finding the fit of the pot joints is crucial to hold the sensor gap tolerances. This system has proved 100% relaible and fault free. The sensors on the front are Rover K cam sensors, the one on the back a vectra cam sensor - as they were free!

Rod - you're only 10 mins from us when at DSN - feel free to pop in for a look about if you have the time.




JK

If Carling made Mini engines
it would probably be like this one!

Went to test it today and the frequency generator function of my USB scope will only go down to 3.91kHz, too high even for me.....

So now I've got to cobble together a square wave generator to do the testing. OpAmp again I think will be easiest if I can find a suitable one in my box of many bits..... Luckily the breadboard is large.

John, if I can figure out exactly where you are I'll take you up on the offer next time I'm at DSN, it will be interesting to see some real technology again instead of just playing at home.

Schrödinger's cat - so which one am I ???

You wouldn't happen to have flip-flops or counters in your box of bits, would you? You could then make a frequency divider and maybe get a reasonable frequency from you USB scope.


Jean

http://www.jbperf.com/

I did think about that Jean but it looks like the scope only has a set of fixed frequency outputs on its square wave generator, whereas I want to vary them by small amounts (ie, front to back) to see how the modified code responds with ignition timing etc. The OpAmp circuit I've found will give me variable outputs over reasonable ranges. I didn't have enough bits in my box though so I've ordered them for delivery tommorow.

Also I want to get this done quickly as the weather, at least in the southern part of the UK, is beginning to warm up so I want to get outside very soon to finish the fuel system etc and actually put this project on the road.....

Schrödinger's cat - so which one am I ???

You can use your JimStim.

Jean

http://www.jbperf.com/

Schrödinger's cat - so which one am I ???

well i have built up 2 of the 3 frequency to voltage converters onto bread board, similar to yours Rod, i have found some signal generator software utilising the sound card and an oscilloscope again using the sound card, i dont know how they will preform in 'real life' but they can create the signal im after i think :)

i cant get my head around the bit of circuit in the data sheet where it selects the maximum voltage so i am looking for another way of doing it.

but im definitely enjoying playing all this again

Edited by Brett on 25th Feb, 2010.

Yes i moved to the darkside

Instagram @jdm_brett

What software are you using with the soundcard ??? I couldn't find anything that would do square wave although for testing a sine wave should suffice.

The select maximum is the one numbered 00794235 on the datasheet, it's the straightforward one as they are just connecting the two outputs in parallel (as the output is open collector, the highest will win and do no damage to the low one) but they show the example using the 8pin chip (VR) not the 14 pin chip (Hall). Further up the thread Paul has redrawn it correctly for the 14 pin chip (but for the rears only).

Just waiting for my next set of bits from Farnell to do the signal generator - even if I can use a soundcard, I've ordered the bits so may as well use them....

Schrödinger's cat - so which one am I ???

http://www.nch.com.au/tonegen/index.html
for the tone generator
and
http://www.electronics-lab.com/downloads/pc/002/index.html
for the oscilloscope witch seems ok and is a full free version
im hoping to test this today

Yes i moved to the darkside

Instagram @jdm_brett

They look good, it seems you're limited to two chanels on the sound but it does square wave and only one chanel on the scope so you'll have to check one at a time.
Have you checked you can run both at once in seperate windows without a conflict on the soundcard ???

My last bits just arrived, Farnell sent 90% of the order by UPS, arrived 9am and 10% by Royal Mail which is later in the day. Wierd policy.....

Schrödinger's cat - so which one am I ???

scope30 can be run in more than one window ( ive just checked), but it seems my mic in is only mono ( old laptop), so i cannot have 2 inputs. it should be good enough to test each circuit one by one but not the whole circuit :(

Yes i moved to the darkside

Instagram @jdm_brett

Well, just finished and tested my 4 square wave generators




I fried one voltage regulator chip on the power supply (why do +regs have their wires in a different order to -regs.....) and nearly fried the first OpAmp when I got VCC+ and VCC- the wrong way around...

However, although it works fine and as the scope shows I can vary the frequencies individually, it is an epic fail.......

I have un-intentionally built a set of proper square wave generators that swing the voltage positive and negative.... the Hall switch will only swing it one way

Back to the drawing board.

Schrödinger's cat - so which one am I ???

i have almost figured out the software, well enough to create a square wave and feed it back into itself, but i also get a wave that goes positive and negative i think with a little audio editing though i can create some simple waves, i can create 2 different out puts but only one input,

and typical, i cannot up load a pic

Edited by Brett on 26th Feb, 2010.

Yes i moved to the darkside

Instagram @jdm_brett

Is it such a problem that you are getting a full wave?

Do the frequency to voltage converters really care?

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

Schrödinger's cat - so which one am I ???

+ & - voltages are just releative. On the square wave generators use +5v as +vcc, 0v -vcc & +2.5v as ground and vola.

EDIT: just make sure you don't acidentally tie 2.5v to 0v else where in the circuit.

Edited by Rob H on 26th Feb, 2010.

Schrödinger's cat - so which one am I ???

Well, as a result of the above, I spent absolutely ages getting the test circuits to work..... dual rail power supplies and single rail power supplies don't mix if derived from the same transformer even though I got the zeros the same (measured). When I cobbled together a seperate power supply for the frequency convertors it all worked fine.
Only tested on one chanel so far.


80mS ~ 1MPH = 0.2V


14mS~6MPH = 1.0V

Then a change of capacitor on my square wave generator and a change of timebase on the scope


4mS~20MPH = 3.3V


2.5mS~33MPH = 5V

And the output is clamped at 5V so it doesn't matter how much I raise the "speed" after that.

The speed/voltage relationship is quite linear and the voltage output reasonably smooth. I was aiming for 0-50MPH but I had to make so many changes to my power supplies I ended up with a higher Vcc than I intended which brings the 5V sooner.

Now to get all 4 chanels working and wire it into MS to see what MPH differences do to the timing etc.

Schrödinger's cat - so which one am I ???

brillo ,most interesting ,well done rod.

Medusa + injection = too much torque for the dyno ..https://youtu.be/qg5o0_tJxYM

well done Rod!!

Yes i moved to the darkside

Instagram @jdm_brett

Got all test circuits working of a single PSU - my mistakes earlier, must be an age thing so re-wired the MS for the new inputs. (the pink wires).



A bit too late to test it all tonight but hopefully tommorow

Schrödinger's cat - so which one am I ???

I look forward to see how it goes.

Jean

http://www.jbperf.com/

thats a busy megasquirt! also keen for results, good to know how it compares to simply modulating the ol' right foot :)

turbo 16v k-series 11.9@118.9 :)

Denis O'Brien.

Whilst the server was down, I've played a fair bit with this.

I got the "inputs" working fine so I could swing the speeds between front and back by about 40% (limited only by my test circuitry) like this





But, as you can see, no affect on ignition timing (bottom left guage).

So, after much frustration and posting on the MS-Extra forum (where some are having a hissy fit over licencing of Patrick's code) I decided to just cobble together two 0-5V inputs having already proved the more complex frequency to voltage and voltage clamping circuitry worked anyway.

When I disconnected the JS4/5 wires (so input voltages could float at random) is suddenly started to respond on timing.

But when I connected the two 0-5V inputs it stabilised and required a massive voltage difference to retard timing.

So I went back to Patrick's notes on the inputs and found the key statement, "Now you only need their derivates deltamu and deltalambda"....

Which I think means I need the acceleration terms, not the velocity terms to drive the code.

Much harder to replicate but trying to twiddle the two trim pots together for the 5V outputs did seem to give an expected result.....

So I'm in two minds whether to try and build something to replicate front(dot) and rear(dot) or just finish testing the frequency to voltage convertors and clamps and build a PCB and put it in the car (assuming I ever finish it...) and test it in real time.

I think I've now seen enough to be sure it works so on with the installation....

Edited by Rod S on 6th Mar, 2010.

Schrödinger's cat - so which one am I ???