How to Build the FreeEMS Firmware to Use With Jaguar

[Fred]

Sorry, I wasn't sure what information you needed... I will try to answer your questions, read on below... :-)

Sorry if that sounded grumpy. I looked at it, but couldn't see a way of being direct and not sounding grumpy and thought "fuck it, if he gets upset that easily he's in the wrong place" good to see that you didn't :-)

It sounds like you're saying that the EST output is a normal ignition output and that, like normal, a spark is fired at the end of the pulse. The only difference being that the DIS module distributes this signal to the correct coil. If only the trailing edge matters, why do you say shorter/longer, why not fixed and timed?

The EST output pulse is based on the TACH input pulse as the standard for 10 degrees BTDC, ie: if we mimic the TACH input as the EST output the DIS coil packs would fire each plug in turn at 10 degrees BTDC. You may be correct in saying fixed and timed.

I'm not saying it's the best approach, I'm just pointing out a hole in the information thus far. Does the beginning of the pulse determine which cylinder to send it to, and if so, when are the tolerances for "correct" for that. If not, then what?

The DIS module takes care of the firing order, we just need to vary the EST output square-wave to change the amount of advance.

Right, but, what if we start our pulse a bunch earlier or a bunch later, and still end it in the correct place, what happens? There must be a tolerance, how tight is it? If it's not tight, yep, the code is there. If it's tight, we might need something special.

The bypass thing is as easy as pie, it can be our first bit of GPIO code, I look forward to writing it! :-)

Fred.

[DeuceEFI]

Sorry, I wasn't sure what information you needed... I will try to answer your questions, read on below...

Sorry if that sounded grumpy. I looked at it, but couldn't see a way of being direct and not sounding grumpy and thought "fuck it, if he gets upset that easily he's in the wrong place" good to see that you didn't

No worries, I'm not easily offended... Learning isn't always nice, easy and polite... lol

Right, but, what if we start our pulse a bunch earlier or a bunch later, and still end it in the correct place, what happens? There must be a tolerance, how tight is it? If it's not tight, yep, the code is there. If it's tight, we might need something special.

From my testing on the Deuce's engine with the MS-2 running the show, it appears that the EST (Ignition Advance) pulse starts after the TACH input and all that matters where the EST pulse ends that determines when the coil fires. And it looks like from the waveforms that I have attached to this post along with in the "docs" directory in my repository, that the EST always rises after the TACH signal and when the EST signal falls the DIS module fires the correct coil pack. So I think we will be OK with code you have already written from your quote above. I don't think I need anything special, but have a look at the waveform PNG file and let me know. (Channel1 - green trace - is the 3x TACH signal from the DIS Module, Channel2- blue trace - is the EST signal from the MS-2 to the DIS module to fire the coil pack at the the proper amount of advance based on the Spark table.)

The bypass thing is as easy as pie, it can be our first bit of GPIO code, I look forward to writing it!

Cool , we just need the DIS-Bypass output to be LOW (0vdc) during 0-300 RPM and HI (5vdc) at any RPM greater than 300 RPM. This tells the DIS module to use it's base timing of 10 degrees BTDC to start the engine, then after it has begun the firing order to turn Ignition Advance over to the CPU. It sounds straight forward, but here again, I'm no programmer, but I'm willing to learn

[DeuceEFI]

Waveforms from OEM PCM at Idle and 3400 RPM can be found here: viewtopic.php?f=67&t=1544&start=10

and in my github repository in the docs directory.

[DeuceEFI]

Fred,

I have uploaded a couple of decoders to the src directory on my repository that I modified and wondered if you could take a look and see if I'm on the right track for:
my 3x TACH signal RPM input with the 1x CAM sensor setup
and
my possible 24x CRANK RPM input with the 1x CAM sensor setup

Thanks,

Andy

EDIT: In Green

[Fred]

OK, sorry for the delay!

Firstly,

I have uploaded a couple of decoders

Let me correct that :-)

I have uploaded a couple of configurations for existing decoders

More accurate :-)

Yes, both look like they'll work OK for you in terms of RPM input. Whether we can use them as is with DIS is still a question in my mind. I've still not determined anything solid from those scope plots. It's a shame that you don't have a saleae to record the signal with a gradual RPM sweep.

You can probably get the engine started without a DIS signal at all. Once you have it running you can experiment with the decoder engine offset, the dwell curve and the timing curve. I'd recommend fixed timing and fixed dwell as a start to that, then vary only the timing with it at idle and see if you can get it to behave with a manual enable/disable on the override line for the sake of testing.

Your setup really needs a decoder all of it's own, or some generalisations added to some of the existing code to allow it to work for best for you. I'll take care of that for you when the time comes.

Time for a new thread!

Fred.

[DeuceEFI]

OK, sorry for the delay!

No worries, we are all busy

Firstly,

I have uploaded a couple of decoders

Let me correct that

I have uploaded a couple of configurations for existing decoders

More accurate

Ah, ok, thanks for the clarification, I didn't think the files I edited were the actual decoders, but wasn't sure what to call them... Now I know... moving on...

Yes, both look like they'll work OK for you in terms of RPM input. Whether we can use them as is with DIS is still a question in my mind.

Is there a video somewhere or do you have a saleae recording that I can play back showing the ignition advance output that exists today from your code that I can compare to what I see on xoscope and on my real oscilloscope?

I've still not determined anything solid from those scope plots. It's a shame that you don't have a saleae to record the signal with a gradual RPM sweep.

I will add that to my list of items to pick up within the next week

You can probably get the engine started without a DIS signal at all.

Yeah, it will run, it uses its built in 10 degrees BTDC advance and sort of idle... Good enough to test

Once you have it running you can experiment with the decoder engine offset, the dwell curve and the timing curve. I'd recommend fixed timing and fixed dwell as a start to that, then vary only the timing with it at idle and see if you can get it to behave with a manual enable/disable on the override line for the sake of testing.

That sounds like a good plan to me

Your setup really needs a decoder all of it's own, or some generalisations added to some of the existing code to allow it to work for best for you. I'll take care of that for you when the time comes.

Wonderful !!! I will get a Saleae logic analyzer so I can give you more meaningful information.

Time for a new thread!

I will start a build thread with separate comments thread once I etch another prototype with the larger pads tomorrow.

Thanks,

[Fred]

New thread:

viewtopic.php?f=54&t=1574

Ironically, I forgot to add you in there, despite having the idea because of you! Fixing now. Done.

viewtopic.php?f=54&t=1574&p=23546#p23546

Sorry for getting lost in the sea of words re the DIS stuff.

Fred.

[DeuceEFI]

Thanks for putting me on the TODO list

I just placed my order for a Saleae Logic analyzer, I should have it early next week

[DeuceEFI]

My Saleae Logic has arrived!

Now I'm able to give you usable information about my sensors

[Fred]

It's not that your old info was unusable, it was just not easy/quick to grok. Nevertheless, I'm pleased that you have a saleae, the logs from them are awesome for diagnostics of stuff like this.