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

Re: AA80E 8-speed

Post by Jim Blackwood »

I have found this by Manjeera Jeedigunta:
bset DDRA,$81 ; configure Port A pin 7 and 1 for output


From Freescale Mosaic:

PORTT is an 8-bit digital I/O port configurable as input or output on a bit-by-bit basis. The PT0-7 signals are available on the Digital Field Header on the PDQ Board. Any or all of the bits in PORTT can be configured as timer-controlled I/O under the control of the processor’s Enhanced Capture/Timer (ECT) subsystem.

To configure PORTT, use an assignment statement to write to the PORTT_DIRECTION register, also called the DDRT (Data Direction Register T) register. These and all of the HCS12 register names are defined in the HCS12REGS.h file in the C:\MosaicPlus\c\libraries\include\mosaic\ directory. Writing a 1 to a bit position in PORTT_DIRECTION configures the corresponding port bit as an output, and writing a 0 to a bit position configures the corresponding bit as an input.

the following C statement configures PORTT as all outputs:

PORTT_DIRECTION = 0xFF;

To configure PORTT as all inputs, use the statement:

PORTT_DIRECTION = 0x00;

If we want to configure bits 0-6 as inputs, and bit 7 as output, we can execute:

PORTT_DIRECTION = 0x80;

To change the state of an output bit on PORTT, use an assignment statement with PORTT on the left hand side to write to the port’s data register named PORTT. For example, if PORTT is configured as all outputs, the following C statement sets all PORTT bits high:

PORTT = 0xFF;


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Looks like it can be done. According to the programmer calculator on my phone, I *think* the right number for pins 5 and 7 inputs and all others outputs would be 0xFA. That would be 1111 1010. Anybody care to confirm that please?

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

Re: AA80E 8-speed

Post by Jim Blackwood »

Or would it be 0x5F?

0101 1111
pins
7654 3210

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

Re: AA80E 8-speed

Post by Jim Blackwood »

Nope, got that wrong too. PT5 and PT0 need to be inputs. all others outputs. So, if I have this right?

Pins:
7 6 5 4 3 2 1 0
binary
1 1 0 1 1 1 1 0
hex
0xDE

So DDRT= 0xDE?

Improper syntax I'm guessing.

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

Re: AA80E 8-speed

Post by Jim Blackwood »

I have taken up the study of "C" programming language, as that seems to be my most reliable option at this time, if perhaps also the slowest one. I'm a poor student of programming. I've proven that over and over again in the past. So I know it will be slow going. But, so far I have found not one thing to indicate that this variant of the MegaShift controller cannot run the AA80E as I have it configured and wired up.

It is regrettable, after all the work I have done to bring this application of the controller to a finished condition, that there is not one person I've been able to find in a position to edit the code to allow it to run this transmission. I really had hoped for more from this community, but I knew from the start that it was a gamble. At the time though, it seemed like maybe this gearbox would become more widely used. It seemed like the smaller Aisin boxes were having controllers developed for them also. I don't know why that all stopped, maybe the new cars are just that much better, so that it isn't worthwhile to enhance older cars anymore. My best option might well be to go out an buy a Miata and just forget about it. I'll have to give that some thought.

I do not know if I will succeed. But I do not know that I will fail either. I do know that I have almost as much determination as I started out with, but I am older. Tireder. Slower to recover and shorter of endurance. Less time remaining to me.

Absolutely everything except the editing of the program is done. But that could well turn out to be the most difficult part of the build.

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

Re: AA80E 8-speed

Post by Jim Blackwood »

I think I've taken this as far as I can go. I want to thank everyone for tolerating me while I've been working through it. But as matters stand I do not feel the Mshift can be configured as a full featured controller for the Toyota 8 speed as the code now exists. I have no confidence that I am remotely able to change that.

What now? The simplest approach is to nerf the controller. Cripple it. Hack off features. The obvious one is the gear position output. That used 4 data lines, I need 2 outputs for solenoids, it has to go. Doesn't have to be a gear position display for the car to run does there? No, I guess not. I can look at what will happen with just 2 data lines and pick the most favorable ones I suppose, I think it can be made to display 1,3,5 and 7 perhaps. Probably 2,4,6 and 8 would be shown as 1,3,5 and 7.

So, if nothing changes that will be my new approach. Maybe that can be made to work. I'll be looking at what changes I need to make to the board. Unsolder one or two fixed jumpers, reassign a couple of circuits that sort of thing. Make a couple of changes in the GUI. Nothing very complicated.

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

Re: AA80E 8-speed

Post by Jim Blackwood »

OK, I've switched the jumpers now so that the LED2 output goes to the EGT2 circuit which is wired to an off-board transistor and out to the Shift Trigger solenoid SR.

LED3 output goes to VB1 which is configured to drive the Clutch 2 solenoid SL2.

PT6 is jumpered to VR2 for Paddle upshift per normal practice.

AD4, line pressure input has no connection (the line pressure wire on this trans is a fault switch only, no pressure transducer)

So how do I configure the LED2 and LED3 outputs for PWM solenoid drive?

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

Re: AA80E 8-speed

Post by Jim Blackwood »

Looks like the use of LED outputs for anything other than the display requires coding.

Since that's not something I can do there's that option gone.

So, what's left? I will look at the possibility of running without some of the shifter solenoids. Maybe it is possible to operate in 2 or 3 gears. If I can do that it would at least be driveable, and maybe I can sort out what is needed on the shift trigger solenoid. At least that way maybe I can drive it.

So, I will attempt to set it up like a 4l60 and see if that can work.

More later.

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

Re: AA80E 8-speed

Post by Jim Blackwood »

It looks like I can pull the jumpers for outputs S3 and S5, which currently are configured for solenoid SL3 and SL4, powering clutch C3 and brake B1. That will leave me with the following gears:
1st: 4.596:1
4th: 1.464:1
5th: 1.231:1 and
6th: 1.000:1

Not a good gear spread and no overdrive, but at least driveable. Short term that's much better than where I am now.

Jim
steveh66
Posts: 11
Joined: Tue Oct 23, 2012 7:26 am

Re: AA80E 8-speed

Post by steveh66 »

Wow. That's a bad ratio jump. And the first gear is probably too much of a granny gear
to start with. But you probably know that already.

I have to go back through your post to have a read what maybe be your options. I think you had a table posted one the configuration of of the sol and gear. If you could start at a 2.5 or 3 would be better. Again you probable know that.

Well at least you got into the code which is farther than I have got so far.

Steve
Jim Blackwood
Posts: 222
Joined: Tue Dec 07, 2010 9:52 am

Re: AA80E 8-speed

Post by Jim Blackwood »

Yeah, it's the only configuration I could come up with that made sense. Maybe after I get it to work I can get another solenoid, which would give me 2 more gears.

The code... well that's a non-starter right there. It has a $1000 program just to compile it. So even if you do know C it's a big barrier. For me it's 2 big barriers. Combine the two and it becomes an impossibility.

But, 4 gears are better than one which is what I have now. 1.863:1 reduction in 3rd. Hey, I should be able to get 3rd gear with all solenoids off. That'd probably confuse the hydraulics, switching them to "limp" mode for 3rd gear, but it might work. Runs very effectively in 3rd with the controller unplugged. Well enough to do a burnout. Then tops out about 45-50mph.

Jim
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