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Megasquirt MS3+MS3X+ jimstim CAS simulation

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Old May 7, 2012 | 08:09 PM
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MS3+MS3X+ jimstim CAS simulation

I can simulate up to about 3800 rpm by turning the rpm pot but then it pukes out and goes to zero.

I have dip switch 5 on for 24/2 (Nippondenso) and the second trigger connected to the cam input on the ms3x.

Any ideas?
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Old May 8, 2012 | 12:08 PM
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I'd like to know that too, but a thought just occured to me. The cable that connects the CAS to the MS3/MS3x is shielded, and grounded to ECU ground. I wonder if the issue is due to interference or lack of proper grounding (the signal past a certain point the simulated signal becomes too noisy and can no longer be read)?
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Old May 8, 2012 | 09:13 PM
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What are your zero crossing and hysteresis pots set to?
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Old May 8, 2012 | 09:33 PM
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all pots are completely anti-clockwise
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Old May 9, 2012 | 06:43 AM
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Mine too.
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Old May 9, 2012 | 03:44 PM
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I've heard of people putting a capacitor on the 2nd trigger output of the jimstim to more reliably trigger. Also, are you running +12v into both the ms3 and the ms3x inputs or +5v from the jimstim?

Ken
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Old May 9, 2012 | 03:50 PM
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The JimStim is set to 12V on both pullups. +5V is run from the JimStim to the JimStimX.

What value capacitor was used for the 2nd Cam?
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Old May 9, 2012 | 05:43 PM
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I have the Jimstim powered by a 12V converter.

Below is a pic of my setup.

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Old May 10, 2012 | 12:26 PM
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Originally Posted by cluosborne
The JimStim is set to 12V on both pullups. +5V is run from the JimStim to the JimStimX.

What value capacitor was used for the 2nd Cam?
I don't remember, I think it was either 0.1 or 0.01 uF.

Ken
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Old May 11, 2012 | 04:41 PM
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How do you add a capacitor to the output of the JimStim? Does it go linline on one of the outputs?
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Old May 12, 2012 | 01:02 PM
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Originally Posted by cluosborne
How do you add a capacitor to the output of the JimStim? Does it go linline on one of the outputs?
It will go between the second trigger on the jimstim and the ms3x cam input.
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Old May 12, 2012 | 01:12 PM
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I tried the .01 uF cap and I got no RPM reading at all.

I really would like to be able to test this thing with the jimstim. My drill will not do 8,000 rpm...
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Old May 12, 2012 | 02:04 PM
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I know, I tried the capacitor inline too but it didn't work either. I was able to test both values. Which is why I ask if it's meant to be inline or tied into the StimJim somehow.
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Old May 14, 2012 | 10:43 AM
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one side of the cap should go to ground, the other side should be on the signal I believe.

Ken
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Old May 14, 2012 | 04:19 PM
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Tried both value capacitors and no difference.
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Old May 14, 2012 | 04:51 PM
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Ok so the capacitor is not the answer. I might try spinning the cas at high rpm this weekend and see if I get different results.
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Old May 14, 2012 | 04:52 PM
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did you try it with one leg wired to ground and the other wired to the signal wire, or did you try it inline?

Ken
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Old May 15, 2012 | 07:37 AM
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Inline--no RPM.

With one leg to ground and one hooked between 2nd Trigger and CAM, RPM reading but otherwise no change. The particular type of capacitor didn't have a polarity marking on it, but I tried different legs on each value with no change in operation.

I should mention that the capacitors are from a 200-in-1 electronic project lab, http://www.amazon.com/Elenco-MX-907-.../dp/B000IXPYSM and I simply used jumper wires to connect the resistor in the lab to the StimJim. The jumper wires were long, so voltage drop could be a factor in whether the capcitor worked or not.
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Old May 16, 2012 | 03:08 PM
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I'll try to get a look at your settings tonight, but I did test a similar config on my bench last night and it worked fine. The only difference is that I was using this on the ms3x board:

http://www.diyautotune.com/catalog/j...led-p-474.html

Ken
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Old May 16, 2012 | 03:14 PM
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I'm using a JimStimX, but I bought mine in kit form.

However, while an assembly error is possible, there isn't much on the board to screw up. It's basically a series of LEDs with current-limiting resistors, a few pots, pin headers and a set of microswitches with a DB37 connector.
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Old May 16, 2012 | 05:46 PM
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I'm playing with the dip switch on the JimStim, and I found that enabling Tach Signal Inversion (dip 8, with dip 5 still on) increased RPM to ~5541 before I lose the RPM signal.
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Old May 16, 2012 | 08:52 PM
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Do you have VROUT wired to TSEL or VROUTINV?

Ken
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Old May 16, 2012 | 09:02 PM
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It was jumpered TachSelect to VRIN and TSEL to VROUT as per http://www.diyautotune.com/tech_arti...zda_fc_rx7.htm

That's what I followed. I need to open the casing to double-check.

--opened it up. TachSelect to VRIN and TSEL to VROUT
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Old May 16, 2012 | 09:10 PM
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Originally Posted by cluosborne
I'm using a JimStimX, but I bought mine in kit form.

However, while an assembly error is possible, there isn't much on the board to screw up. It's basically a series of LEDs with current-limiting resistors, a few pots, pin headers and a set of microswitches with a DB37 connector.

I think you will find that if you look at the jimstimx that the cam pin just connects directly to the ms3x pin that I am jumping to so there really isn't much room to mess anything up.
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Old May 16, 2012 | 09:15 PM
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Originally Posted by cluosborne
It was jumpered TachSelect to VRIN and TSEL to VROUT as per http://www.diyautotune.com/tech_arti...zda_fc_rx7.htm

That's what I followed. I need to open the casing to double-check.

This is the way mine is configured.
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