timed outputs?

Testing and development of Megasquirt 3

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JAM
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timed outputs?

Post by JAM »

As a drag racer previously running many different electronic boxes (delay box, shift actuator, msd box with 3 step etc) with a carburetor, followed by a change to ms2 batch fuel control, and now to into MS3X the power of these units has decreased the need for all of these "bandaid boxes".

I now have capability of full sequential fuel/spark, revlimiters (burnout,launch, hi side) shift outputs and on and on....

This is incredible to do this all in one box and many thanks to those who have put so much effort into making this happen. The last box for me to remove is the delay box, essentially a variable delayed output based on an input (ie trans brake button leaving on top bulb)

just wondering if it has been explored or something like this would have any other benefits/applications?
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Re: timed outputs?

Post by JAM »

Sorry, guess this was a stupid question :oops: :oops:
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Re: timed outputs?

Post by jsmcortina »

I don't think anyone has asked for that before?

James
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JAM
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Re: timed outputs?

Post by JAM »

I see, I guess outside of drag racing may have no value...
First question should be what level of undertaking this would be on a software / hardware level?
Second question should be could anyone else benefit from something like this?

We use timers for the following:
Ignition timing changes X seconds from transbrake release
Transbrake delay from release of button
Throttle stops for super class racing (8.90 heads up racing )
Some use it for stages of nitrous control

Anyway, just poking around out of curiosity, obviously if it is little benefit to the masses there is no reason to mess with it.
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Re: timed outputs?

Post by jsmcortina »

The timing retard after launch was added just the other day. Nitrous control timed from launch is already in place.

The other timed on/off outputs are not presently there.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

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JAM
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Re: timed outputs?

Post by JAM »

jsmcortina wrote:The timing retard after launch was added just the other day.
Well thats good news! is that in the most recent alpha code? It the amount of time a user defined variable?

EDIT: I just found this link http://www.msextra.com/forums/viewtopic ... 31&t=44792

Hmmmm..... I am liking what i see. As far as timed features in MS3X what resolution/repeatability is it capable of?
i.e. my delay box i set the delay at X.XXX seconds from button release....
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Re: timed outputs?

Post by jsmcortina »

OK, so here's what I have in mind.
(The timed hold-on is a generic feature, the throttle stop would be specific.)

You come into stage, press and hold your button.
Internally, the code sets an output pin low - this would be wired in the loom to the "launch" input and connects to your trans-brake through a relay.
Top amber light and you release the button.
The counter starts rolling and then at X.XXX seconds the output is released, the transbrake disarms and the launch revlimiters and disabled.

At this point a second timer (launch) timer would start, after Y.YYY seconds the throttle-stop output is activated.
This output is kept active for Z.ZZZ seconds (Is this part correct?)

(As an aside, I really don't like throttle stops! "Oh he's broken, oh no he hasn't")

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

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JAM
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Re: timed outputs?

Post by JAM »

jsmcortina wrote:OK, so here's what I have in mind.
(The timed hold-on is a generic feature, the throttle stop would be specific.)

You come into stage, press and hold your button.
Internally, the code sets an output pin low - this would be wired in the loom to the "launch" input and connects to your trans-brake through a relay.
Top amber light and you release the button.
The counter starts rolling and then at X.XXX seconds the output is released, the transbrake disarms and the launch revlimiters and disabled.

At this point a second timer (launch) timer would start, after Y.YYY seconds the throttle-stop output is activated.
This output is kept active for Z.ZZZ seconds (Is this part correct?)

(As an aside, I really don't like throttle stops! "Oh he's broken, oh no he hasn't")

James
James,
If I had half the intelligence you have I would be dangerous! :lol:

I think you have that spot on, that is almost exactly how you set a typical delay box with timers in it for t-stops.........
In fact the thought i had for wiring I think is how you described it, ground an input at the steering wheel button to activate the launch rpm and the transbrake.... and an output pin would ground a relay (or opposite) after the internal timers decided it was time to do so? the relay would connect to the transbrake? and maybe other output would activate the t-stop cylinder?

Oh, and as for the throttle stops I actually agree... this is why I found a top dragster chassis this last winter and trying to set up a turbo dragster to run heads up or TD classes
Last edited by JAM on Sat Apr 28, 2012 7:16 pm, edited 1 time in total.
jsmcortina
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Re: timed outputs?

Post by jsmcortina »

OK, I got motivated.
(Features like this aren't as mentally challenging as investigating wheel decoder issues.)
launch.png
James
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JAM
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Re: timed outputs?

Post by JAM »

You have got to be kidding me..... GENIUS! :yeah!:

if i am grasping this right this means that i can reduce from 6 boxes to 1 to do everything!!. so will this be in the next alpha code??

amazing... is there a chance that a unit like the megaview could be configured to be able to change say the transbrake delay?
just wondering as that is a variable that you will not know till you get to the lanes.. either way, sweeeeeet!
Black99rt
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Re: timed outputs?

Post by Black99rt »

This is freakin awesome. I think it's time for an ms3 to compliment my new transbrake.

How about some logic for air shifters on three speeds? I dont know the best generic way to approach this though, I haven't even tried mine out yet.
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jsmcortina
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Re: timed outputs?

Post by jsmcortina »

Black99rt wrote:How about some logic for air shifters on three speeds? I dont know the best generic way to approach this though, I haven't even tried mine out yet.
Write some pseudo code or explain in words how you'd like it to work and I'll have a think on it.

To be honest, some of this stuff is pretty simple to implement - WAY easier than investigating a wheel decoder.
i.e. I have spent far more time trying to understand the LS1 mis-sync issue than the total time for adding and bench testing the most recent batch of drag racing features.

James
I can repair or upgrade Megasquirts in UK. http://www.jamesmurrayengineering.co.uk

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Black99rt
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Re: timed outputs?

Post by Black99rt »

I've never owned or used one yet so I'll have to think about a generic approach that doesn't require too many inputs. I don't know how many drag racers have wheel or driveshaft speed sensors hooked up to their ms3 yet. (they probably have another box for that!)

The most basic is just bang two upshifts but not three after launch at a different rpm each time (or on delays). Some sanity checking based on wheel speed could ensure the MS knows what gear it is in. I would be interested to see integration with wheel speeds so you don't up shift while spinning, but most sanctioning bodies probably wouldn't allow this. A manual mode with steering wheel upshift button would be neat too.

An arming switch would be a good idea (or maybe just switch power to the solenoid external to the MS) you don't want that solenoid wacking your hand on the shifter when you aren't making a pass. I'm not sure how one handles the driver pedalling it.

We probably want to get users who have used this hardware before to weigh in, I'm not so good at following sanctioning bodies rules, and am just interested in the most complete solution.
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JAM
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Re: timed outputs?

Post by JAM »

Black99rt wrote:I've never owned or used one yet so I'll have to think about a generic approach that doesn't require too many inputs. I don't know how many drag racers have wheel or driveshaft speed sensors hooked up to their ms3 yet. (they probably have another box for that!)

The most basic is just bang two upshifts but not three after launch at a different rpm each time (or on delays). Some sanity checking based on wheel speed could ensure the MS knows what gear it is in. I would be interested to see integration with wheel speeds so you don't up shift while spinning, but most sanctioning bodies probably wouldn't allow this. A manual mode with steering wheel upshift button would be neat too.

An arming switch would be a good idea (or maybe just switch power to the solenoid external to the MS) you don't want that solenoid wacking your hand on the shifter when you aren't making a pass. I'm not sure how one handles the driver pedalling it.

We probably want to get users who have used this hardware before to weigh in, I'm not so good at following sanctioning bodies rules, and am just interested in the most complete solution.
Interesting thoughts.....

Here is my take on the situation......

I run a 2 speed glide, I have an electric solenoid to smack my shifter into hi gear, I shift on rpm. This can be accomplished by use of a general outputs and set at desired rpm to make the shift. The solenoid is activated and jabs the shifter into hi gear, as soon as the rpm drops after the shift the solenoid retracts. the down side is that if you shift at 7500 and then go through the traps at 8000 it is activated for a short time again at the end (between 7500 and 8000) while in hi gear . Not a big deal for a glide but not as easy on a 3 speed

If a 3 speed was to be shifted on time, would it not be similar to the throttle stop with X seconds after the trans release and Y seconds after 2- 3 gear change?

I would say that if you are at the level of looking at smoking the tires and trying to get the car to recover that is on the driver. Usually if the tire spins you want to upshift to settle the car down, a higher gear has less mechanical advantage over the tire..... not sure if you have ever had tire shake but that can settle it down as well. So if he wants to short shift it that is easily done or hold it in gear longer your arm is stronger than the solenoid
Black99rt
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Re: timed outputs?

Post by Black99rt »

Well if the MS is aware of what gear you are in, and you short shift 1-2, it can still handle 2-3 once you are hooked back up. The ability to pick either time or rpm seems important to me.
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JAM
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Re: timed outputs?

Post by JAM »

Black99rt wrote:Well if the MS is aware of what gear you are in, and you short shift 1-2, it can still handle 2-3 once you are hooked back up. The ability to pick either time or rpm seems important to me.
how about a position sensor on the trans or gearshift.....?? RPM or time is a good option i agree 100%. I am just in a little easier boat with one shift point I think
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Re: timed outputs?

Post by jsmcortina »

JAM wrote:how about a position sensor on the trans or gearshift.....??
MS3 supports an analogue "gear position sensor"

James
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Black99rt
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Re: timed outputs?

Post by Black99rt »

So a string or linear pot connected to to the gearshift or linkage, and you define the ADC ranges that represent each gear? That sounds perfect for this.
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JAM
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Re: timed outputs?

Post by JAM »

If I machined an adapter/mount to go from a tps to the gear selection shaft (on center) would that work?
JAM
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Re: timed outputs?

Post by JAM »

I was looking at the PG trans and it would be really easy to put a tps on for the use of gear position input as outlined in the analog section of this link
http://www.msextra.com/doc/ms3/speedgear.html

I am using 2 of the 3 spare 0-5 inputs with ADC's for fuel and oil pressure sensors and would like to use one for a VSS.... I can tell I am going to need more.

On another note i have just split the 5V ref from the tps 5V ref between tps/oil/fuel press, how many times can i split this signal before i run into trouble? :?:
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