Toyota A750f Transmission control

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.
Paulwolf
Posts: 9
Joined: Thu Aug 12, 2010 1:07 am

Re: Toyota A750f Transmission control

Post by Paulwolf » Fri Aug 20, 2010 4:07 am

Lance, you are probably correct. Theose inputs are from the auto. To get 1st gear, in logic, you need 2nd from the auto and 1st from the selector.

ie. in operation to get first you pull the shifter back to 2nd then across to 1st. same for 5th back to 4th and across for 5th

the shift pattern looks something like

p
R
N
54
3
21

mate, as it stands, I am starting to be a bit disallusioned with the whole (toyota) process. I would be happy with a manual contoller, with paddle shift.

I can do away with all the shifter inputs, all the control tables, and just shift on the fly.

I would only need PRND inputs, which are already available.

Is this a realistic option? I still have no idea about modifying the code.

Paul

Paulwolf
Posts: 9
Joined: Thu Aug 12, 2010 1:07 am

Re: Toyota A750f Transmission control

Post by Paulwolf » Fri Aug 20, 2010 5:15 am

Because P N and R all use the same solenoid output, could i put all on one input. Then 4 and 5 on one, 3 on one , and 2 and 1 on one input? something like this

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

Re: Toyota A750f Transmission control

Post by Bernard Fife » Fri Aug 20, 2010 6:26 am

Paul,

The way the code is set up, the paddle shifters work to allow shifts up to a maximum of the gear the shift lever is in. So if you didn't want to use the lever to shift manually, but instead only wanted to use the paddle shift inputs, then the shift lever can stay in high gear (Drive/5th) and the paddle shifter inputs will let you manually select any forward gear (*and* you would still have full auto ability using the 12x12 gear table).

Doing the above would mean you would only need inputs for N, R and D.

Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw

Paulwolf
Posts: 9
Joined: Thu Aug 12, 2010 1:07 am

Re: Toyota A750f Transmission control

Post by Paulwolf » Sat Aug 21, 2010 3:30 pm

ok then, i think I might be able to fit them all in, I have just received the GPIO board and megashift kit, so I can start work on the development of this.

Just need to read up on the code, and I will be away, Can you recommend any good books Lance?

Paul

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

Re: Toyota A750f Transmission control

Post by Bernard Fife » Sat Aug 21, 2010 4:15 pm

Paul,

For a complete textbook on programming the HCS12 family of processors, including MegaSquirt-II's MC9S12C64MFA, the best book I have seen is:

"The HCS12/9S12 : An Introduction to Hardware and Software Interfacing" by Han-Way Huang
Hardcover: 880 pages
Publisher: Delmar Learning
Language: English
ISBN-10: 1401898122
ISBN-13: 978-1401898120
(This is the standard 3rd year university electrical engineering textbook on
this topic. It also includes a CD with freeware compilers and IDEs, among other things. Unfortunately it is around $100)


If you are looking for a concise introduction to programming the HCS12 (but for the
D256 variant) try: https://www.ee.nmt.edu/~rison/ee308_spr06/lectures.html (May generate a security error, but the site itself seems fine.)

The MShift code itself has *lots* of basic level explanations in its comments as well, so you may not need anything more than a copy of the code in main.c: http://www.msgpio.com/manuals/mshift/GP ... oj1100.zip to learn all you might want to know.

Also, I am putting the finishing touches on the latest V2.000 code. This will have:
- up to 8 speeds allowed,
- fourth shift solenoid output added on spare2 (PA0/VB2/Amp12),
- fourth shift lever input added on PE1/GPI1/Amp5,
- CAN pass-through added,
- added spark retard for shifts,
- added spark retard by gear (above a user specified load threshold) for 2nd and higher gears.

So most of the changes you need might already be in the new code. I will likely post it early next week in the 'Latest Code Updates' thread here: viewtopic.php?f=4&t=20

Lance.
"Never wrestle with pigs. You both get dirty and the pig likes it." - George Bernard Shaw

bigo4x4
Posts: 1
Joined: Tue May 10, 2011 2:53 am

Re: Toyota A750f Transmission control

Post by bigo4x4 » Wed May 11, 2011 11:40 pm

Howdy, Just wondering if there was any further progress on controlling the A750F transmission?

I noticed that S1, S2 and SR Solenoids are on/off but common grounded, where the MSgpio uses common power source and switches ground. Can the configuration of the GPio board be changed through software or is an adapter board required to invert the control signals?

I think the same would go for the PWM control for the remaining 4 solenoids as the MSGpio provides constant 12v to all PWM solenoid outputs and the negative is controlled via PWM.

I have one of these gearboxes mocked up in my offroad 4wd race truck but this is the lates hurdle to sticking with this transmission.

cheers

Andrew

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

Re: Toyota A750f Transmission control

Post by Jim Blackwood » Sat Sep 03, 2011 9:08 am

I think it should be possible to use a different output transistor and tie the source to + on the board. To do that it might be necessary to bend the transistor lead so it doesn't go into the board and use a jumper wire but I'm pretty sure it can be done that way. Something I'll probably have to look at too on the AA80E.

JB

user name:
Posts: 1
Joined: Wed Sep 17, 2014 7:27 am

Re: Toyota A750f Transmission control

Post by user name: » Wed Sep 17, 2014 7:30 am

Did anything ever come of this? Im wanting to see if this MShift will control an A750F transmission that Im wanting to swap in.

Marz
Posts: 1
Joined: Tue Dec 20, 2016 1:21 pm

Re: Toyota A750f Transmission control

Post by Marz » Tue Dec 20, 2016 1:42 pm

Hello,
Has anyone managed to successfully control a A750f transmission with Micro TCU? I would also like to swap out my current auto with A750F.
Regards

Mario.

vl-alexander
Posts: 2
Joined: Wed Dec 28, 2016 11:59 pm

Re: Toyota A750f Transmission control

Post by vl-alexander » Mon Jan 02, 2017 5:06 pm

I did it.

We put A750F + toyota 1UZ-FE vvti into toyota hilux surf and sucessfully wired this transmission to GPIO/Mshift.

Shifter has 8 positions,
P R N D 4 3 2 L

but only 6 are used:
R D 4 3 2 L.

using diodes i coded signals from 6 lever outputs into 3 inputs:
egt2, egt3, egt4
lever.png
lever.png (3.19 KiB) Viewed 2526 times
Also i used tacho signal from engine as input shaft speed, and VR speed sensor at end of AT as output shaft speed.

Ouputs:
S1, S2, SR - +12v driven (common ground) shift solenoids

SLT - PWM line pressure
SLU - PWM lock up

SL1, SL2 - generic PWM outputs.

SL1 and SL2 is some kind of black magic for me. I am still did not found any useful information how to control them right.
What i found, that some combinations of duties on theese solenoids cause no upshift from 4 to 5 gear.

Only one problem that i have is hunting gears. shifting in driving is almost fine, but shifting from P or N into Drive or Reverse is worst.
Changing line pressure duty is only one thing that really affects on shift kick, but i can not set pressure less 40% (soleniod duty more 60%)

So there is the questions to Mshift code developers - how can i bypass that limit? I am almost sure that toyota transmission use full 100% range to control line pressure.

Post Reply