AA80E 8-speed

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.
Post Reply
Jim Blackwood
Posts: 222
Joined: Tue Dec 07, 2010 9:52 am

Re: AA80E 8-speed

Post by Jim Blackwood »

I got the power flow and shifting sequence figured out, as well as the most likely use of the unknowns (SLU, SL, SR) and added some really good information to the bottom of the spreadsheet. That should help. It's about as concise and detailed as I could make it given my interpretation of the data. SR is still something of an unknown but perhaps Walt can shed some light on it.

The ATF pressure switch, it turns out, does not monitor line pressure! It monitors SL1 output pressure and is a fault indicator. We may or may not want to bother with that, and it could leave us another circuit to use for something else.

Lance, there is a lot in this last part, feel free to take your time sorting through it. Hopefully with this you will have enough information to know which circuits are going to match up the best. I will be flying out to Arizona Saturday for a week's vacation and probably be out of touch, but I'll do anything I can to help before I go, and I should be back by the next Friday.

I know we want to make this usable as a stand-alone controller. I think that is a good idea. But, I'm not against using circuits elsewhere in my build if it makes things easier or gives better functionality. I think I will have some excess capacity.

My main priority is fast and precise shifting, so it seems to me the shifting solenoids should all connect to the Megashift, as well as the upshift and downshift manual switches. Other than that I don't much care which board the inputs and outputs come from. In auto mode I don't expect it to have lightning speed anyway. Anyway, I'm more of a nuts and bolts guy so there's not much point in my insisting on anything when it comes to what goes where. You've got pretty good judgement and you know the lay of the land, I'm happy to follow your lead.

Feel free to modify the spreadsheet as you see fit, or make notes on the side and I'll pretty it up when I get back. It should make a dandy reference document.

JB
Bernard Fife
Posts: 1696
Joined: Fri Apr 04, 2008 1:28 pm

Re: AA80E 8-speed

Post by Bernard Fife »

Jim,

I will dig through the material when I get a chance.

Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw
Jim Blackwood
Posts: 222
Joined: Tue Dec 07, 2010 9:52 am

Re: AA80E 8-speed

Post by Jim Blackwood »

Update: Getting closer. I now have the wheels and rear tires (over 2K) and am coating the headers with Techline Cermachrome. Major tasks still preceding tranny control include the air scoop/throttle body, driveshaft, shifter, and new lift mechanism for the tilt front end, plus condensers for the intercooler and A/C, installation of an A/C compressor and completion of the drive belt system. My timeline has these preliminaries completed by the first of the year, then I can return to the tranny controller in ernest.

Lance, is there anything in the works for a hardware upgrade for Megashift? I was thinking with the push towards more gears (Ford reputedly is now offering an 8 speed for some applications) that we might need more drivers. Any thoughts on this?

JB
Attachments
MGB-V8 enderlie1.jpg
MGB-V8 enderlie1.jpg (61.95 KiB) Viewed 13839 times
Before latest upgrade
Before latest upgrade
MVC-897F.JPG (96.77 KiB) Viewed 13839 times
Bernard Fife
Posts: 1696
Joined: Fri Apr 04, 2008 1:28 pm

Re: AA80E 8-speed

Post by Bernard Fife »

JIm,

The current code handles up to 6 gear solenoids (and 8 speeds, of course). The current DIY GPIO hardware won't change, though there are plans for an smaller SMT version for non-DIY'ers.

Additional drivers can be easily mounted on an extension board for the current DIY GPIO, much like the MAX9926/constant current driver extension board were are already planning.

Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw
Jim Blackwood
Posts: 222
Joined: Tue Dec 07, 2010 9:52 am

Re: AA80E 8-speed

Post by Jim Blackwood »

OK, Thanks Lance, the MAX9926/constant current driver extension board is a development I didn't know about. I also think I saw something about Dodge using an 8 speed. Probably won't take long for GM to match that. How many solenoids they actually use really depends a lot on their control scheme and power flow layout I guess, maybe Toyota went a little overboard.

Anyway, I wanted you to know I'm still here. Just distracted by other parts of the build for awhile.

JB
Token
Posts: 5
Joined: Wed Jan 11, 2012 12:44 pm

Re: AA80E 8-speed

Post by Token »

How goes the A650E development? I want to get a GPIO board to test on this platform but want to avoid "re-inventing the wheel" where-ever possible.

To contribute, I have both the flow chart (not verified) and control schematic PDF to attach. I am trying to get up to speed on the GPIO as best as possible. If it can control 4 solenoids, and three PWM solenoids, I can't see how this wouldn't work. As mentioned in other threads, the GPIO would not work by grounding a + signal from the tranny, but must send out a + signal (grounded at the tranny). But thats a physical layout alteration, the hard part for me is finding documentation on 4 solenoid and 3 PWM solenoid control (1-4 solenoids, its a 5 speed, one PWM is for line pressure, another for TC lockup, the third I'm still trying to figure out).
Attachments
Transmission.pdf
(98.98 KiB) Downloaded 593 times
A650e flow chart.PNG
A650e flow chart.PNG (170.43 KiB) Viewed 13772 times
gross polluter
Posts: 11
Joined: Mon Nov 21, 2011 9:41 pm

Re: AA80E 8-speed

Post by gross polluter »

Token wrote:How goes the A650E development? I want to get a GPIO board to test on this platform but want to avoid "re-inventing the wheel" where-ever possible.

To contribute, I have both the flow chart (not verified) and control schematic PDF to attach. I am trying to get up to speed on the GPIO as best as possible. If it can control 4 solenoids, and three PWM solenoids, I can't see how this wouldn't work. As mentioned in other threads, the GPIO would not work by grounding a + signal from the tranny, but must send out a + signal (grounded at the tranny). But thats a physical layout alteration, the hard part for me is finding documentation on 4 solenoid and 3 PWM solenoid control (1-4 solenoids, its a 5 speed, one PWM is for line pressure, another for TC lockup, the third I'm still trying to figure out).
A650E will work. Before using the A340E I'm currently running, I was using some weird A343E with an A650E valve body. You have to add P-Channel MOSFETs to the shift solenoid outputs since they are high side switching. The other solenoid in question is accumulator backfill. The higher the current supplied, the softer the shift "feel". I probed a stock car and found that it sits at about 20% duty cycle until a shift is performed, then the backfill solenoid current is brought up to the desired shift feel.
Token
Posts: 5
Joined: Wed Jan 11, 2012 12:44 pm

Re: AA80E 8-speed

Post by Token »

Did you use 2.111 or the beta 4.006, or did you have to customize the code? Looks like you setup the 1-3 solenoids per write-ups, and then also the spare optional 4th solenoid setup for #4, TCC is another separate component provided for, and pressure control yet another already provided for feature, and then you used one of the MS3x PWM generic outputs for the last component left, the accumulator backfill?

I was hoping to make the GPIO a standalone controller, but still excited to see full tranny control possible with a combo.
Token
Posts: 5
Joined: Wed Jan 11, 2012 12:44 pm

Re: AA80E 8-speed

Post by Token »

Another question would be the shifter input. The A650e in the attached PDF has one input for each selection going to the OE ECU, making for a total of 8 inputs (P, R, N, D, 3, 2, L, M). The Mega-shift only has 4 inputs. P and N can share one, D its own, R its own and I suppose 3 its own. M doesn't need to be tapped, the software engages M without the need of an external switch, I suppose some well placed diodes can give 2 and L the ability to be input?
gross polluter
Posts: 11
Joined: Mon Nov 21, 2011 9:41 pm

Re: AA80E 8-speed

Post by gross polluter »

Token wrote:Did you use 2.111 or the beta 4.006, or did you have to customize the code? Looks like you setup the 1-3 solenoids per write-ups, and then also the spare optional 4th solenoid setup for #4, TCC is another separate component provided for, and pressure control yet another already provided for feature, and then you used one of the MS3x PWM generic outputs for the last component left, the accumulator backfill?

I was hoping to make the GPIO a standalone controller, but still excited to see full tranny control possible with a combo.
Using 2.111 as it was downloaded from this site, no modifications. I am currently using MS3X for accumulator backfill. If you want full standalone then you can run without accumulator backfill, but your shifts will be noticeably firm. You can back down the line pressure a bit in the lower load bins to soften up the shifts, but it gets to a point where the trans just slips into gear. Honestly if I had to live without accumulator backfill it would not bother me a bit. Perhaps I could start a thread to determine the possibility of having a general PWM output for such functions. It would be nice to have all of the trans functions on GPIO, I agree.
Token wrote:Another question would be the shifter input. The A650e in the attached PDF has one input for each selection going to the OE ECU, making for a total of 8 inputs (P, R, N, D, 3, 2, L, M). The Mega-shift only has 4 inputs. P and N can share one, D its own, R its own and I suppose 3 its own. M doesn't need to be tapped, the software engages M without the need of an external switch, I suppose some well placed diodes can give 2 and L the ability to be input?
Yeah, you can split some signals out so they pull multiple inputs low. With 4 inputs you can have 16 logical shifter positions, so you're OK with 8 positions. I went simple on my trans; P N and R all share the same input, D 2 L have their own inputs.
Post Reply