Chrysler 41te Trans Control

[tjabo]

That's GREAT news Matt, I'll take a look around for one of those! I've been prowling around eBay a bit again to see if I could scam a useable oscilloscope for a reasonable price, but the problem there is that I have no idea what I'm looking at. . . Also Matt, have you guys started having any appropriate case endplates made yet for the GPIO board? I'd rather buy something professional if possible than to hack one up myself.

Steve, I think Lance is saying that any tach input can be used for the overrev control, which I would think could be used for the purpose you're talking about (just setting it to shift at an RPM that's lower by enough to accommodate the lag, assuming the shift times and rates of acceleration in the different gears could work that way). It really does seem to me that you'd be better off though to choose a shift speed for each gear that has you into the next gear at the right time taking into account the shift speed and everything. . . .

Have you seen this page?:

http://www.msgpio.com/manuals/mshift/tuning.html

Thad

[Bernard Fife]

Steve,

There is no rpm input in non-CAN mode in the current code. RPM comes over CAN only for two reasons:

1 - this is how most non-electronic transmissions - without full data - shift (by load and vehicle speed only), and
2 - sorting out tach signals is a significant challenge and it seems a waste to repeat this all over on the GPIO board when the V3 board has it already.

The code measure or estimates the input shaft speed, and where lock-up is close to 100% (at higher rpms) this could be used to force a shift (but it isn't in the code now).

I could add a tach input circuit, I suppose. This would have to go on the V3 circuit that will be used for input shaft speed sensing, so the user would have to choose one or the other. It wouldn't be perfect, and I would not want to provide things like wheel decoding (the signal would have to be a one "zero-crossing" per ignition event sort of thing).

It is better, and likely easier, to use MS-II and CAN, though. MS-II has wheel decoding, filtering, etc. and will always be better than the GPIO at getting useful info from tach singals. When CAN is used, the maximum rpm can be user spec'd, and the trans will upshift when the rpm is reached if the 12x12 (loadxspeed) table hasn't told it to already. There is also a minimum rpm that will force a downshift if the rpm drops too low.

As a general note to all, the reason we shift by vehicle speed and not rpm is that it is very easy to get the rpms such that the controller oscillates (ex. the speed happens at the upper limit so the trans upshifts, but the drops below the lower limit after the shift is completed and the transmnission downshifts, etc.). By using speed, the speed before and after the shift is nearly the same, and the code cannot oscillate.

Lance.

[tjabo]

Sorry guys, I guess I misunderstood the situation with the non-CAN RPM signal (as with many other things! ).

Regarding the DMM, I ordered this yesterday:

http://www.amazon.com/Mastech-Auto-Rang ... 6H812MJY6T


Hopefully it's not total crap!

My wife doesn't want me getting within 10 feet of her minivan with a Mega-Anything, but I should be able to figure out the wiring well enough to use this meter to get a frequency off of one of the solenoid wires without even cutting anything. Assuming we don't have it nailed down already by then.

Steve, do you think you have a good source of information for those solenoid frequencies, or are you kind of tapped out in that regard?

Lance, just checking that you got my PM?

Later!

Thad

[Bernard Fife]

Thad,

You are getting most things right , and the rpm functioning might be described incorrectly in the docs (since the original intent was to have it act as you describe). I need to review the docs in light of the many chages that have (and will) take place. If you (or anybody) notices anything that doesn't look right or is contradictory, please let me know and I'll fix it asap.

I got your PM, and thought I replied, maybe I forgot to hit 'send'. In any case, the beta unit is coming from an island off the west coast of Canada, so it might take a while (depends on how long customs takes to process it as well). It could take as long as 3 or 4 weeks sometime (though sometimes it is less for no obvious reason).

Lance.

[racerstev]

I'll give it a shot w/o the rpm input, I'm sure it will work fine that way.. I'm also rethinking the TPS mode, this trans is stout
enough to handle boost even with a softer shift.

I'll keep working on the PWM frequency as well..

Steve

[racerstev]

Ok new plan, I have a delay box with a shift output on it. You can control up to 4 shifts with either rpm or time based outputs, it will take care of
the transbrake as well!

So all I need to do when I race is put it in manual mode rather then auto mode and let the delay box handle the shifting..

[tjabo]

FRANKENVAN!

Lance, thanks for the update on the shipping situation too. That might not be bad in the long run, it looks like there is a lot of learning for me to do in the interim.

If I run across anything in the documents that looks different than it should (*from what I know*), I'll let you know as you asked.

Thad

[tjabo]

Lance,

I have to go back and re-read your explanation (and Daniel's additional information I think?) of the bench testing process to see exactly what I will be able to do with what as far as providing separate VSS and crank signals, but since I may have another week or two before the board arrives, I ordered a JimStim kit today. Hopefully I'll be able to get that put together in short order so I'll have it available for the bench testing. Without brushing up on your prior post, maybe I can use the JimStim to provide the Neon crank wheel signal and use the RPM signal from my old-school stim for the VSS input?

Thanks,

Thad

[Bernard Fife]

Thad,

That should work. The only issue is that I believe the stim's tach circuit get's its power from the attached MegaSquirt, so if you don't have it plugged into MS, you have to wire up a 5V supply on pin 26, and ground the 5V supply on pin 7,8,9 10 (one of them, might be that any will do). The tach signal signal comes out on pin 24.

You can oe this by jumpering directly onto the stim (bypassing the DB37), the relevant locations can be found from the schematics: http://www.megamanual.com/v21stim.htm. Fort example, the tach signal comes out on R4 - use the end furthest from the DB37

Anohter possibilty (for anyone looking for a ssecond signal) is the crank wheel pulser, which needs no additional hardware if the speakers are amplified and have a headphone jack (http://www.megamanual.com/router/crankwheelpulser.htm).

However, you can do quite a lot by using just one signal, and jumpering the VSS to the tach signal (though you cannot use missing tooth wheels - so might have to change the MS-II settings to get a usable rpm).

Lance.

[tjabo]

Lance,

Thanks for suffering my electronicallyignorant questions!

I've looked around the house and work, and I don't seem to find any headphone jacks on my amplified speakers. So, my old stim says V2 on it, but it looks like it is essentially this:

http://www.megamanual.com/v22manual/v1stim.htm

One thing I'm not understanding is whether I need the standard 9v stim input on pin 28 AND the 5v reference voltage on pin 26 or not. I think so, but I kind of got the idea from your post that maybe I could just power up the tach circuit on the old stim with the 5v and be good. . . . ? I'm guessing that was just wishfully lazy thinking on my part.

Do you think I'll be able to pull an additional 5v reference voltage off of the JimStim and then ground back to the JimStim (probably while separately providing the normal power to the power plug of the old stim. . . . . I wonder if I can split the power from my one wall wart into both stims. . . Hmmmm. . .

Oh, on a separate note, while looking around for solenoid frequency information that I didn't find, I came across some comment on the brake switch causing the CC to kickout, which made sense to me after I read it. Is that a feature of the code so far, or is that pretty well accommodated by the load/VSS table?

Thanks,

Thad