The latest madcap idea from S2central !

[mark_s2]

'From the sinewave I can generate a square wave using a fairly simple circuit - that gives me nice clean edges to drive counters which then trigger a crank reference pulse every 135 teeth and camshaft ref every 270 teeth. If I can't generate a suitable crank ref pulse I am just going to have to sample it with an ADC, write to ROM and play it out thru a DAC at the right time.' - why not use a PIC?

[SteveH]

Heath + Robinson

Paul, you must have too much time on your hands

[S2central.net]

The internet is a wonderful invention ... just found some crankwheelpulser software hosted on the megasquirt site and I have it emulating the flywheel teeth signal and camshaft pulse with the correct timing. Piccies to follow... Oh and I am hoping to be PIC free on this stuff - I can't be bothered learning my way round another controller - and getting all the right tools to write software for it. This is an old school invention - its like a little science project - I had my 7yr old son helping me tonight - holding scope probes and listening to the waveforms... Its like Shamu meets Flipper !

[S2central.net]

I'll need to look at the source code for that CWP utility though - it generates a CMP pulse of approx 4 teeth wide - I need it to be more like 16 teeth... Maybe easier to build my own timer & counter though, cos I need that anyway to simulate the crank ref pulse - and have that arrive reliably within the CMP window.

[S2central.net]

Some of this evenings findings recorded for posterity... I'll take a look at modifying the C source for this - the more I think about it, the better it would be to simulate RPM and CPS. I might need help from some gamely software folk on here - I'm not so hot on C and I've never programmed on a PC environment before. If thats a dead-end then its a good source of the RPM signal and I can do the rest in simple hardware.

Can't upload it - stupid file size limits... Will fix and retry later.

[Nuvo]

I can take a look at the code if you like.

[S2central.net]

I've found the section of code that needs tweaked. Will ping back ASAP.

[S2central.net]

@Nuvo - here's the section of code that needs tweaked... You need to download the CWP source from http://www.megamanual.com/router/crankwheelpulser.htm first of all...

Then find the CrankWheelPulserDlg.cpp file

And circa line 600 is this section of code which writes the CMP signal.

// Write the cam sync
if(icamsync == 2) // Generate CAM channel (right) if selected
{
camangle = camangle + angledelta;
if(camangle >= 720.) camangle = camangle - 720.; // cam pulse width = 10 degrees
cbuf = 0;// cam no pulse
if(camangle > camchk && camangle < camchk + 10.) cbuf = 255;// cam pulse
fputc(cbuf, fp);// cam
}

The 720 refers to crankshaft degrees so thats correct of course.

Q1 - Can you please change that '10' to a '40' to create a wider pulse and recompile into PC executable ?

Q2 - Rather than have it generate the CMP signal, could you change the 720 to 360 so we get a pulse every crank rotation and create a pulse structure such that the signal contains the value 128 forever except one tooth width at 255 followed by a tooth width at 0 and recompile that ?

[S2central.net]

File attached with waveforms & some info from last nights initial tests.

[Nuvo]

Okay Paul, I'll get back to you when I get a chance to look a this.

Have I understood you correctly that you want a single binary with both these changes? Or do you want two binaries, one containing changes as described in Q1 and a second file with the changes listed in Q1 and Q2?

[S2central.net]

Oh yeah - two separate bins please - cool !

[Nuvo]

Okay, here is the first build with your change request in Q1. I'll take a look at Q2 when I have a bit more time.

[S2central.net]

Nice one NUvo... Just tried it and the CMP pulse is definitely wider - circa 8ms at idle which is right ball park. I need to do more detailed timings off the car though.

However - that build is broken somehow as it didn't generate the RPM signal here - just the CMP. Weird... I see you started to add some extra radio buttons... Maybe this is WIP for something

[Nuvo]

Nice one NUvo... Just tried it and the CMP pulse is definitely wider - circa 8ms at idle which is right ball park. I need to do more detailed timings off the car though.

That's a good start.

However - that build is broken somehow as it didn't generate the RPM signal here - just the CMP. Weird... I see you started to add some extra radio buttons... Maybe this is WIP for something

Hmm that is odd, I haven't made any other changes to the code or the interface.
The only other change I made was the way in which the MS Foundation Class library is linked. This was a consequence of the comiler I am using.
I retrace my steps and see if I can fix that.

[robert_n]

There is a whole industry based around this so you should be able to source info about how to set up a model for this (or get a free one). In my work all of the models (be it engine/suspension/whole car etc) are set up in a Simulink (Matlab environment) and there are many commercially available and some free (i think) models for environments like this. It can be a really powerful tool for testing ecus. The style of modeling used is ideal as you can change parameter sets to change engines etc. I am not sure what hardware you would use with a system like this for private use though as all our stuff costs a fortune.