4L80E code

A forum for discussing applications and implementations of the MegaShift transmission controller code for the GPIO from B&G. This can control up to 8-speeds and 6 shift solenoids (plus a 16x9 table for controlling a PWM line pressure valve). It has manual and fully automatic modes (16x9 load x speed table), with under and over rev-limit protection, and full data logging of all inputs and outputs (among many other abilities). A TransStim to test your completed board is also available.
gui67
Posts: 134
Joined: Tue Oct 05, 2010 11:58 am
Location: Strasbourg, France

Re: 4L80E code

Post by gui67 »

Tanks Lance, I will test it today and let you know
Guillaume
gui67
Posts: 134
Joined: Tue Oct 05, 2010 11:58 am
Location: Strasbourg, France

Re: 4L80E code

Post by gui67 »

Hello Lance,
I just tried it, unfortunately, this code does not solve the issue, I still have the same behaviour: spike to 0 in VSS at 88km/h, leading to downshift to 3rd. (I can give you a datalog if you want). This particuliar issue was solved in the code update between 4.129b and 4.129c.
What you said at this moment about the origin of the issue:
This code fixes the 1300hz glitches, at least on my bench. The problem turned out to be a subtle interaction between the VSS and timer overflow interrupts that only occurred in particular combinations of parameter settings and input values. In the code attached above, timing offsets were added to subsections of the interrupt code to significantly reduce the likelihood of colliding interrupts. Hopefully it works for you. It may just move the problem to another rpm (though I don't see that on my bench..yet). I did do a very slow sweep from 391 to 4340 Hz without problems.
During this test, I had the problem described by Andrew I think:
I went to First gear manual (not with the shift buttons: with the lever. Then I pushed the lever to 3rd manual, but it stayed in first: it did not shift either automatically or with the buttons. mGear shows -99 ??? I tried to stop, go in Neutral, Drive, Reverse, Park... it always stayed on -99.
I had to shut down the car, and then it was again OK. I can send you a datalog later if needed.
gui67
Posts: 134
Joined: Tue Oct 05, 2010 11:58 am
Location: Strasbourg, France

Re: 4L80E code

Post by gui67 »

Here is the datalog from the -99 manual gear.
Ap67et10
Posts: 42
Joined: Tue May 13, 2014 12:06 am

Re: 4L80E code

Post by Ap67et10 »

Guillaume,

Dave (mill3833) was also having this problem. I too have experienced this issue also with the -99 and error 33 as shown on your datalog along with mine and Dave's too. In this thread viewtopic.php?f=4&t=829&start=10 dave mentioned turning off lever error reporting and it seemed to function as expected after that. I will give that a try, but I think it should function without a workaround as Lance had mentioned in the thread I posted.

It seems like there have been a few people with some very specific faults that are primarily related to

1. lever position causing GPIO to hold a gear when it shouldn't.
2. VSS problems which seem to be causing all sorts of odd behavior.

If I were you maybe first try turning off "lever error reporting" and see if you can determine if in fact you have 2 separate issues, and if you can sort out the one first, then work on the second. That is how I have been trying to resolve the lingering random issues I now have.

Andrew
gui67
Posts: 134
Joined: Tue Oct 05, 2010 11:58 am
Location: Strasbourg, France

Re: 4L80E code

Post by gui67 »

Hello Lance,

Did you have the opportunity to check for the 88km/h downshift (1800Hz VSS)?
the new code you made did ot manage to solve it. I think the modification you made between the 4.129b and 4.129c should solve the problem. It is what solved it last year.

Andrew, I turned off the lever error reporting. for the moment, I did not get the issue again. I think I got the eroor when putting the lever in first gear to fast or going out of first too fast. (I don"t know why I did that aas I usually use the paddle shifters if I need to downshift below 3rd...
Bernard Fife
Posts: 1696
Joined: Fri Apr 04, 2008 1:28 pm

Re: 4L80E code

Post by Bernard Fife »

I think the modification you made between the 4.129b and 4.129c should solve the problem. It is what solved it last year.
gui67,

The problem is that those changes made from that time are still in the code. So we are looking at something else, though it might be similar (I am unable to get any speedo issues at 1800 ± 80 rpm on my bench).

However I have made a few small timer ISR changes to the code in the attached 4.144g test code that you might try:
Monitor_4144g.abs.s19
(73.17 KiB) Downloaded 800 times
GPIO_MShift_4144.ini
(220.15 KiB) Downloaded 783 times
Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw
gui67
Posts: 134
Joined: Tue Oct 05, 2010 11:58 am
Location: Strasbourg, France

Re: 4L80E code

Post by gui67 »

Hello Lance,

I am sorry I did not answer you earlier, I did not had the opportunity to drive the car in the last 2 weeks.
I tested it this evening, it seems to be fine: I drove it 10km, tried always to stay around 88km/h, which made the problemm ealier.
It did not occur: no down-shift to 3rd, it did not removed lock-up, so it seems the problem is solved. I will try it longer next time and let you know if I see anything strange or not normal.
I also deactivated error reporting for the gear changes and tried downshifting or upshifting quickly to First: no problem anymore.

Thanks for the time you spend to solve this issue. for the moment it seems that it works perfectly for my application: 4L80e + paddle shift + line pressure sensor + 7 segment display gear indicator.

Guillaume
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