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Thread: DIY LTCC or similar system for LT1s

  1. #121
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    Quote Originally Posted by vilefly View Post
    Yup. there is only one like it. You might want to grab the pigtail connectors to it as well.
    I will grab a few on saturday and report back.

    So from what I understand about the northstar module, it only ever needs 2 of the 3 sensors to actually function. either both crank signals 27* degrees out of phase I think? or one crank sensor (think its 24x?) and the 1x cam sensor. Having all 3(both crank and the cam sensor) allows for faster start?

    It seems maybe the 1x cam signal would not be that difficult to convert to with the factory opti-wheel signals?

  2. #122
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    Quote Originally Posted by johnny_b View Post
    I will grab a few on saturday and report back.

    So from what I understand about the northstar module, it only ever needs 2 of the 3 sensors to actually function. either both crank signals 27* degrees out of phase I think? or one crank sensor (think its 24x?) and the 1x cam sensor. Having all 3(both crank and the cam sensor) allows for faster start?

    It seems maybe the 1x cam signal would not be that difficult to convert to with the factory opti-wheel signals?
    Well, what I am not sure of is exactly where in the rotation that the cam sensor sends its quick 1-pulse. Maybe 67.5 degrees after the 1st pulse from the leading sensor. +/- maybe 2 degrees. I am not sure if the ignition module can run on one crank sensor and one cam signal, but it would be cool. We might be able to cheat. If a cadillac comes in sometime, I will grab a better scope pattern from it with pulsewidth measurements if possible.

    You know what? I think I will make a round slide rule that will fit inside of a cd case with a 27 deg set of spaced windows so I can check my synchronization at any time. Am sick of getting out the ruler and protractors. Might help me think clearer amidst distraction.
    Last edited by vilefly; 10-05-2017 at 07:47 AM. Reason: grammar

  3. #123
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    Here is a flawed picture not to a cd case's scale, but accurate. not done with the overlay. Still using cadillac coil numbering, but we really know that COILS A=1/4 B=2/5 C=7/6 D=3/8. In that order. After #1 TDC, coil B is armed for firing, and is the next to fire.
    reluctor template w-TDC-cam sync.png

  4. #124
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    Ok, codebreakers.
    I found some arduino code that is a cam/crank signal generator for multiple engines. It is called ardu-stim. It has an optispark configuration file in it, but I have no arduino stuff yet to test it. I did not see a northstar one, though. It has alot of engine patterns, though. The code looks like it can be converted for hardware clocking, if scaled properly. I don't know enough about the code yet, but I know that one and zeros placed in a data array should work fairly well.
    Here is the link https://gitlab.com/libreems-suite/ardu-stim
    Tell me what you think. My arduino mega 2560 arrives tomorrow, and I will start my learning process.
    Last edited by vilefly; 10-06-2017 at 07:52 AM.

  5. #125
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    I think I have a data array that should produce a single northstar crank signal if placed in a loop with an output to a pin.
    {1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 1, 0, 0, 0, 1, 0, 0, 0}

    In this array, there are 95 elements, including zero.
    position 0 = 1st pulse from crank sensor A
    crank sensor B = lags behind A by 7 positions
    position 2 = cyl 1-4 TDC
    position 18 = cam sensor pulse
    position 26 = cyl 2-5 TDC
    position 50 = cyl 7-6 TDC
    position 74 = cyl 3-8 TDC

    Hope this looks accurate, I checked it 3 times before posting.
    I'll bet if we read the eprom in the delteq unit, we will find this data set also.
    Last edited by vilefly; 10-06-2017 at 09:18 PM. Reason: more data

  6. #126
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    Northstar can run without cam signal. Starting time will be around 45 seconds though{from service manual}.
    The other obstacle is the signal these sensors produce. It is some kind of frequency signal with different DC%. The same as running a pwm valve or VSS sensor signal. A similar signal can be found on lt1 PCM at pin a12. It is a fixed freq signal with DC% varying with TPS change.
    This signal will be completely opposite to opti 0v-5v signalling.
    What is inside a norhstar ICM. Is there some form of processor, maybe a pic will help alot.

    How hard will be to control Ls coils and how opti signal will be divided between two devices.
    I think nortstar ICM will be step back. The main focus should be on running ls coils.

  7. #127
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    Page 5 has the link to the northstar patent, which gives lots of detail to the operation. Lots of AND gates, too.

    Not sure what year ECM pin A12 is referring to. Does not appear related to the ignition system in my schematic.

    With this software approach, the 5v optispark signaling will run a counter synched to a northstar pattern. In the case of the Delteq, they use optispark to count through memory locations inside the eprom, and simply output logic hi or low. You run the output through capacitors to simulate an AC signal.

    I agree that I need to get my butt in gear on the hardware coil decoder, but I am still ordering chip adapters so I can prototype easier. Everything is surface mount soldering these days. Irritating. I am bouncing around as to which brands and styles of chips to use. The logic has to match. Once that is ironed out, I can start building a prototype. This will take some time to sort out properly, but time is limited, and software/firmware solutions are easier write up.

  8. #128
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    the northstar signals fed to icm seems it will be complicated to nail unless we get some good scopes of the 3?
    if using the northstar icm will be a step back then,

    thinking from a hardware , software perspective or some combination of the two, could we not piggy back the opti signal into the arduino.

    from there couldn't the high-res signal be used as a clk and then count the number of clock cycles occurring when the low res signal is 1?
    with 8,3,5,2 having a unique number of clk cycles occurring during their low res signal being 1 this could be used to then sync the firing order switching cylinders upon each next low res rising edge?
    still use the ecm est signal but use some type of hardware that selects which coil to arm based off the firing order sync?

    disclaimer:
    a lot of this stuff is way over my head so i may have just sounded like a complete idiot.
    Last edited by johnny_b; 10-07-2017 at 03:24 AM.

  9. #129
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    The answer to all those questions is yes, johnny. You've got the idea. The great part about a data loop referenced like this allows us to sync up with any of the long slots of the low res signal, and jump into the loop at the exact data point. Gotta love random access. I am still learning about program structure.

  10. #130
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    Yes Johnny, The basic way I'd do the program is by decoding the low + high patterns to load an 8-bit register with the correct starting pattern (8-bits with a single 1 to represent the current cylinder). Then, use the low + high leading edges to rotate the register. The tricky part is putting in a continuously operating decode and compare routine that corrects the rotating register when an error occurs. Does this routine correct it every time, correct it when it's wrong or have some more complex logic behind it?

  11. #131
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    Since low res signal is time based, and the width of the slots cant be measured, due to rpm speed. The higher the rpm the shorter the pulse.
    I suggest to use leading and falling edges as pointers. What you need to count is between rising edge and falling edge and schedule next firing cylinder.
    For example the falling edge of the widest low res slot indicates that #1 tdc is 46 degree away. Since PCM will control timing and there is lag at fast rpm transitions, which can be up to 6 degree, we will be limiting the total advance so , I guess that will only be needed for syncronisation. After that each rising edge will switch to next coil and we will get full (90-adv) degree advance to schedule the coil and wait for est signal to fire.

    http://www.megamanual.com/seq/coils.htm
    Here is some info on ls1 coils and dwell times.

  12. #132
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    Hmm. can't get the ardu-stim signal generator firmware to compile on my arduino mega 2560. Some kind of interrupt-driven programming is used. Very beyond me at this time. Lots of errors.
    I did however, get the speeduino firmware to run on it. Kinda neat. Will not support anything beyond waste spark ignition on a v8, due to only 4 driving signals output. Better suited to a 4 cyl or less. Bank fire stuff on more cylinders. I was hoping that I could have used the injector drives to select coils, but nope. Shame. I think I will fuel inject the lawnmower, though. heh. Very configurable when it comes to crank triggers.
    Last edited by vilefly; 10-09-2017 at 02:37 PM.

  13. #133
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    It seems member dave w has come up with a solution for the vortecs to run the 0411 pcm. The project looks rather affordable and simple. it requires the use of a vortec distributor combined with his piece. It seems to me that this could be used on the LT1 by drilling a hole in the intakes the same way people do when they swap lt1 intakes on to tpi setups. I love EEhack so much id really hate to ditch the original pcm, and the ultimate dream for lt1 lovers, at this point with the amazing software already available, really would be coil on plug with the original pcm. but his project looks promising. just thought id share.

    edit: after further discussion with dave w, his project will not support coil-on-plug at the moment.
    Last edited by johnny_b; 10-10-2017 at 12:13 AM.

  14. #134
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    ok. I think I found a place that still sells the non-fashionable DIP-14 IC packages that I can work with. Jameco electronics still has the old ICs that I remember, and super cheap, too. I have placed an order to try out my schematic. Unfortunately, I already orded SOIC chip adapters also. Oh, well.
    Has anyone used my northstar data array to generate a signal, yet? I am still reading about loops and stuff, despite being attacked repeatedly by "the Squab".

  15. #135
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    So, Johnny, how's the northstar ignition module working for you? I still need to learn how to write a program to generate crank signals from the array I made. I was hoping you knew how, since I have over extended myself on solving multiple problems.
    In case everything fails, I have a toothed northstar wheel designed in a DXF file that should bolt up to the harmonic balancer. I am working on the dual crank sensor bracket. This was inspired by the Indmar LT-1 ignition system installed in the Mastercraft boats. The waterjet cutter service would cost me about $80-$100 for one wheel. Less if I have more made, but I am still working it all out with no final design yet. The belt system goes on the left or right, depending on application. How inconvenient.

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