PWM bump box

Testing and development of Megasquirt 3

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papiogxl
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PWM bump box

Post by papiogxl »

I have a decent size group of cars that are looking to change the bump box a bit to be less violent. The current settings depend on the car, and how much power they are putting to it on the line.

The problem with the current setup is if you use 1 initial bump, it tends to be rather violent and unsettles the car quite a bit
2 bumps sometimes works ok, but if you turn the power up from how it was tested, its easy to deep stage.
3+ bumps is also ok, but with the small values that you end up using, the first of the bumps doesn't really move the car, and each bump afterwards gets a bit more movement. If whatever the set number is isn't enough, you have to press the button repeatedly to get the car to move.


What we're looking for is just a simple PWM setting that is active as long as the button is held. It would only need two User defined fields: PWM DC, and PWM PW
This should allow the car to slowly inch into the beams without unsettling the car, or rocking out of the beams (which a couple of the guys have had happen and lost the race because of it)

Thanks!
The Ratchet RX7
1988 RX7 powered by 12V VR6
Ms3x, ID1000's, e85, pt6266, NX wet kit.
Stock block w/ arp hardware
TH400
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Phish806
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Re: PWM bump box

Post by Phish806 »

This is exactly what I am wanting as well. Other companies offer this option so I know it's easily doable. Losing a race due to an underdeveloped bump box is a horrible way to go out. Can we make this happen please ?!?
nathaninwa
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Re: PWM bump box

Post by nathaninwa »

A few weeks ago during testing this happened to me. Two bumps and a little more rpm set me so deep that I red lit. So I started dragging the foot brake, which took the initial bump and up to two more to get shallow staged. Worked but thought something different needed done
Volvo 940, 2jzge, MS3Pro, daily
240Z, 2JZ, MS3Pro boost control
TonyR85
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Re: PWM bump box

Post by TonyR85 »

Why not use one of the "Generic PWM" outputs?

-Tony
nathaninwa
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Re: PWM bump box

Post by nathaninwa »

Because it needs to interrupt the transbrake signal from the ecu
Volvo 940, 2jzge, MS3Pro, daily
240Z, 2JZ, MS3Pro boost control
indyjonn
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Re: PWM bump box

Post by indyjonn »

I do not have any issues with the bump feature on my car. Its pretty consistent bump to bump. This is with MS3pro Ultimate.
TonyR85
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Re: PWM bump box

Post by TonyR85 »

nathaninwa wrote:Because it needs to interrupt the transbrake signal from the ecu
Relays. I would like to see it built into the code and use internal hardware though.

Tony
nathaninwa
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Re: PWM bump box

Post by nathaninwa »

indyjonn wrote:I do not have any issues with the bump feature on my car. Its pretty consistent bump to bump. This is with MS3pro Ultimate.
I don't either, if I leave it at the same rpm and same boost level it will bump in pretty constant. But raise the launch rpm in the staging lanes it will bump farther, and sometimes before I started dragging the foot brake it will rock back and forth and not settle in before the yellows come on. Each tranny and solenoid type are different. Be neat to press and hold the bump button and setup the dc so it just kinda rolls in slow that last 6 inches
Volvo 940, 2jzge, MS3Pro, daily
240Z, 2JZ, MS3Pro boost control
slow94formula
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Re: PWM bump box

Post by slow94formula »

I've been wanting this for a while now. Have done it with a few cars that have Holley on them, but haven't figured out how to get it to work with MS3 on mine. I would hope it could be fairly simple to just add a drop down box that says "specify number of moves" or "moves while button pushed"

Hopefully someone will confirm if this is a possibility. I know we have some of the best guys capable of making changes like these happen. Just a matter of time.
papiogxl
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Re: PWM bump box

Post by papiogxl »

Yeah, this would be most helpful to the no prep crowd, there's usually a significant difference in power between the first round and later rounds.
The Ratchet RX7
1988 RX7 powered by 12V VR6
Ms3x, ID1000's, e85, pt6266, NX wet kit.
Stock block w/ arp hardware
TH400
8.8 IRS
wes kiser
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Re: PWM bump box

Post by wes kiser »

From an end user or code standpoint, the way I would envision this working is as a separate selectable mode (perhaps call current way momentary, and new way creep).

In creep mode, you would then have two user definable times. A "creep" time that defines how long the brake is off, and a hold time that defines how long it is on. Basically PWM with defined times. As long as button is held, it would pulse at this frequency.
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taank
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Re: PWM bump box

Post by taank »

There is a post in one of the groups on Facebook where we have got this figured out. I. We have successfully made a “creep stage”. Still working on what to call it.

https://youtu.be/88SFle3ssyI
nathaninwa
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Re: PWM bump box

Post by nathaninwa »

Love it. Anymore info?
Volvo 940, 2jzge, MS3Pro, daily
240Z, 2JZ, MS3Pro boost control
taank
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Re: PWM bump box

Post by taank »

triggering creep off a loop. The loop is watching port statuses on a generic pwm output and a digital input. When both port statuses show active, the loop is active, and that triggers a bump request. When the loop is active, the bump request is commanded at the frequency the generic pwm output is configured. there is hope that this will be simplified in a firmware change.
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nathaninwa
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Re: PWM bump box

Post by nathaninwa »

That's great. Thanks for sharing. Hopefully this can be implemented in the firmware soon
Volvo 940, 2jzge, MS3Pro, daily
240Z, 2JZ, MS3Pro boost control
badboss351
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Re: PWM bump box

Post by badboss351 »

Hello, does anyone have clear instructions for wiring and setting this up?

Thanks,
SSCamaro98
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Re: PWM bump box

Post by SSCamaro98 »

Anyone have a wiring diagram?
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