Firmware live stream happening this weekend: viewtopic.php?f=13&p=43195
For anything you'd like to see added to Speeduino
By DanSankey
whilst this may have to be on a seperate arduino, it may be something worth considering, the megasquirt guys have one now that is pretty common

basically in the auto transmission there are a number of solenoids, this number depends on the transmission type, these solenoids are either on or off, with a combination of the solenoids each gear is selected.


this shows how the state of the solenoids selects the gear, this is a complicated transmission that also has 4 PWM solenoids but most are quite simple.


i found this userform on good ol' google images that would be a simple way for a user to program the trans controller, other features of it could be a gear display and paddle shift.
By noisymime
I'll preface this by saying I know next to nothing about trans controllers, so forgive the silly questions.

For the most part, are they all just on/off solenoids? On/Off valves are super easy and very low processing, so that would be easy.

In your picture, what are the SLT, SLU and SLN solenoids for?
By DanSankey
that particular gearbox is a complicated 5 speed one from lexus, i just had that image because i have that trans. for most, as far as i'm aware there are just three on/off solenoids, here's more info about the other solenoids


if you could code something that let you select up to 5 gears and up to 4 solenoids per gear you would cover most auto transmissions, you could also have a provision for a kickdown button.

i'm not massively familiar with auto boxes myself, i need to do more reading, but it does look like it could be quite simple.
By dazq
My understanding is the pwm valves have map tables associated with them according to rpm n map.the pwm must be setup to match the transmitted torque at the time of shift ,to much and the shift is hard and damaging to the box , to light and it will slip/flair also damaging the box!
I too would like a trans controller for a STD type autobox (5hp24 I think off hand) but I also need to resolve the controller for my CVT box too (a zf vt1 31a).even on this fairly simple box if you shift badly it will damage the box, see the attachment of rover's description on its operation.
If you are in a hurry an wanted to use for instance one of the ms trans units it would be quite easy to add a simple interface for speedy to talk in a way it would understand.,that's what the can bridge will I hope do for all can capable units.. :-)
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By cx500tc
And with a few keystrokes... Transduino is brought to life.

Having done so... what does the unit need to monitor and control?

I'd think engine speed and throttle position, transmission fluid pressure and temperature, and transmission output shaft speed.
And at least 8 outputs... just 'cause you need to control the solenoids and a "speed sensor" output for the odometer on some vehicles wouldn't hurt.
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DanSankey wrote:Something like this, if it makes sense.
Yes, that's a good basic start. Simple to get going and cover many transmissions with simple operation. Certain complicated models aside, there still have to be adjustments to the selections in order to make them accurate and/or preferred under certain conditions. For example, the Torque Converter Clutch (TCC) for converter lockup bangs pretty hard if just ON/OFF, and an adjustable tapered PWM is usually employed to soften the engagement. It's also selectable OFF at higher-throttle as they will usually slip if not a racing version. Of course, they also have to unlock at a chosen rpm when slowing to a stop if not released by auto downshift selection of 1st gear. ;) Likewise, the gear shifts are ON/OFF, but often need a delay of one solenoid or the other to prevent rpm 'flare' on the shift, or two gears clashing if one of the clutch packs or bands are slow or fast to release or apply in that design. Not big deals, but the tweak adjustments allow it to able to cover most circumstances, models, and driving styles. Just plan for it later in the project polishing period.
By raven007
I have given this alot of thought over the years...

About as well toss in MAP monitoring.

Really you need the "load" value from that.

take the venerable TH350 for example. It has a "kickdown" cable thats the equivalent of a TPS and the modulator which is basically a mechanical MAP sensor. it also has a mechanical governor which equates to a output speed sensor. to a certain degree, input pump speed affects shifting as well.

The kickdown cable monitors for throttle openings beyond a certain % and when reached, shuttles the mechanical valves into a lower gear.

The modulator controls shifting based upon engine load. High manifold pressure = soft low rpm shifts. Low manifold pressure = hard high rpm shifts. The modulator controls line pressure and as such affects operation of the mechanical governor as well as available pressure to shuttle valves and total available pressure for clutch application. Higher engine speed also provides more flow and pressure (to a point) as well. This is a very basic high level explanation and does not take into account the accumulator, orifice sizes in the valve body seperator plate, and a whole buttload of other mechanical bits.

Now throw in later transmissions with a lockup converter. We will deviate from the GM stuff for a moment and talk about the 904 Chrysler. These had purely mechanical lockup systems which worked like another gear. Sometimes it worked very poorly as there was little line control regulation based on load etc. So you end up with shuttering when lock up engaged or had transmissions which wanted to downshift but hang in lockup.

GM used a more better design with an electric solenoid. This is true for both early "switch pitch" TH400s and later TH350s ("C" variant plus its variously crappy cousins like the TH200) with lockup. These can be used with a vacuum switch and brake pedal switch to make the lockup function properly. The point being made.... a good trans controller will also sense when the brake pedal is depressed to drop out of lockup.

Brake pedal sensing can also be used to trigger a downshift. I have a beater 2005 Corolla, if you are coasting and using the brake very lightly to not rear end the car in front of you the trans controller downshifts after about ten seconds to use engine braking.

So I would say input wise (basic):

engine speed
input speed (NOT ALWAYS ENGINE SPEED!!! case in point the 4L80E and Chrysler Ultra Drive transaxles and many more)
output speed
gear shift position sensor (this can be resistance (ford maybe?) or pressure switches on the valve body or an encoder on the linkage someplace
trans temp
line pressure* optional but very nice for troubleshooting and datalogging; some oem units have this, most older electronic units do not
brake pedal switch

paddle shifters, bump shifter etc inputs
mode switch (manual)
mode switch (sport/economy blah blah blah)
transfer case status (to be useful this would require switchable maps IMHO)

at least 4 shift solenoids
line control
torque converter control
misc indicators

(as a footnote, knowing engine speed vs input speed gives a torque converter slippage factor, which can be useful in determining load as well)
By dazq
Just cos i was bored and wanted to play with fritzing i started a layout for a gpio type board which could also be a trans board...
So far i have
8 fet high current outputs
8 analogue inputs with optional bias resistor (ala temp sensor style)

Now i was going to add 8 digital inputs and 8 low outs
The low outs i thought to use the driver like on the v04?
But what about the inputs? Just clamp with resistor and diodes or a transistor, or an opto? What do you guys think?

And what other basic inputs should it have....?
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I'm thinking the digital inputs should be whatever is most foolproof, so perhaps opto. Those inputs have been called-out by others. As planning placeholders, I would designate PWM outputs for TCC (lockup) and EPS (pressure), and digital outs for Reverse, Reverse Lights, and Start-Safety switch (neutral/park or NSS). Even with one more hi-amp digital for "other", that leaves four to operate shift solenoids, which (in most designs) translates to permutations of 16 gears as I calculated below, and does not even consider using the low-outs instead. :D My 4-speed OD trans with lockup uses four solenoids for everything (one pressure, one TCC, and two shift), plus one optional for reverse lights. Default is 2nd gear and max line pressure for limp-home with no solenoid inputs (disconnected controller {0,0}) for example.

Number of shift solenoids permutated to number of possible transmission gears:

Solenoids: 1
Permutations: 2
{0} {1}

Solenoids: 2
Permutations: 4
{0,0} {0,1} {1,0} {1,1}

Solenoids: 3
Permutations: 8
{0,0,0} {0,0,1} {0,1,0} {0,1,1} {1,0,0} {1,0,1} {1,1,0} {1,1,1}

Solenoids: 4
Permutations: 16
{0,0,0,0} {0,0,0,1} {0,0,1,0} {0,0,1,1} {0,1,0,0} {0,1,0,1} {0,1,1,0} {0,1,1,1} {1,0,0,0} {1,0,0,1} {1,0,1,0} {1,0,1,1} {1,1,0,0} {1,1,0,1} {1,1,1,0} {1,1,1,1}

Solenoids: 5
Permutations: 32
{0,0,0,0,0} {0,0,0,0,1} {0,0,0,1,0} {0,0,0,1,1} {0,0,1,0,0} {0,0,1,0,1} {0,0,1,1,0} {0,0,1,1,1} {0,1,0,0,0} {0,1,0,0,1} {0,1,0,1,0} {0,1,0,1,1} {0,1,1,0,0} {0,1,1,0,1} {0,1,1,1,0} {0,1,1,1,1} {1,0,0,0,0} {1,0,0,0,1} {1,0,0,1,0} {1,0,0,1,1} {1,0,1,0,0} {1,0,1,0,1} {1,0,1,1,0} {1,0,1,1,1} {1,1,0,0,0} {1,1,0,0,1} {1,1,0,1,0} {1,1,0,1,1} {1,1,1,0,0} {1,1,1,0,1} {1,1,1,1,0} {1,1,1,1,1}

Low-out placeholders (if all outs are either hi or low amp) could be speedometer (dig and analog), pressure, temp, etc.

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