rusEFI display

Hardware inside and outside of the ECU
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mobyfab
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Re: rusEFI display

Post by mobyfab »

I've had this kind of project in mind for a few years now... had even made a pcb using a beaglebone, but never finished it.

The idea was to create a base board for an existing cpu board (now it would be a cheap SODIMM A20 SOM) to drive the LCD and an STM32 to handle the IO.
You can even add fancy bars/indicators with addressable RGB leds such as the APA102.

STM32 would be connected to the SOM via USB or serial.
SOM would be running a custom fast boot linux image, easy to develop a GUI, as well as update it.
LCD has to be sunlight readable (transflective)
The case would be made of stacked laser cut panels, water resistant.

Something like that:


We'll see after I finish my ongoing projects :)

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kb1gtt
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Re: rusEFI display

Post by kb1gtt »

I should mention I have a BBB and LCD7 shield. Wink wink. However the programming is beyond me. I plan to use that setup for a EMC2 CNC controller.
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puff
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Re: rusEFI display

Post by puff »

these are sort of unreadable ;-(
speaking of virtual dashboards, only the big luxury brands can afford really neat solutions. sad to say, the majority of diy stuff is ugly.
as for availability issues, steppers have been used in dashboards in 1988, they are being used in dashboards now (probably, in the majority of economy class vehicles). but indeed, all those AI and EV trends make it difficult to predict what will be there in the next 5-10 years.

caish
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Re: rusEFI display

Post by caish »

I'm new here so forgive me but reading over this thread,
Interesting conversation about gauges etc.
Why not drive a simple scooter or motorcycle tach/speedometer?
Many options are of a design could be integrated into a custom dash...
https://www.ebay.com/itm/Multifunction-Motorcycle-Digital-Gauge-Speedo-Tacho-Odo-Meter-Kmh-Indicator-Well/233024644338?fits=Model%3AScooter&hash=item364159e4f2:g:EssAAOSwQwFb~gM5
I've actually bought a couple to try and get working on a yamaha dualsport but failed...
if I can find one in the shop, I[ll be gladto send it to someone to play with.
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kb1gtt
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Re: rusEFI display

Post by kb1gtt »

Nice find. For $38, its certainly something to consider. My key concern is 7in (180mm) by 3.7in (96mm) is perhaps a bit small. That's about the size of my hand. Do you know if they have something like this which is a bit larger?

I see a pin out on that connector. I'm not sure how those pins are driven, but I can guess they could be driven by a Frankenso board. It would be nice if they provided a bit more data on the electrical connector. I don't know if those are high side drive, vs low side drive, or how many volts or amps they consume etc. It would be nice if that was provided. I suspect Frankenso can drive these, but I'm not sure. Also if they had a serial interface, that would be handy.
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caish
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Re: rusEFI display

Post by caish »

kb1gtt wrote:
Tue Apr 23, 2019 9:47 am
Nice find. For $38, its certainly something to consider. My key concern is 7in (180mm) by 3.7in (96mm) is perhaps a bit small. That's about the size of my hand. Do you know if they have something like this which is a bit larger?

I see a pin out on that connector. I'm not sure how those pins are driven, but I can guess they could be driven by a Frankenso board. It would be nice if they provided a bit more data on the electrical connector. I don't know if those are high side drive, vs low side drive, or how many volts or amps they consume etc. It would be nice if that was provided. I suspect Frankenso can drive these, but I'm not sure. Also if they had a serial interface, that would be handy.
As with so much of Chinese universal stuff, documentation is weak at the best, barely have a schematic, I'll look around the shop this afternoon, and see if I can find it. I had one very similar to this one.
Be glad to send it off to someone to play with.
As they are are designed for scooters etc not sure would find a larger version. But possible... I'll do a bit more digging on fleaby..

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Re: rusEFI display

Post by 960 »

I made a custom can dash for my racecars some years ago.

It uses steppers and a arduino.

I made faceplates in Adobe Illustrator, printed them at overhead-plastic sheets and glued them to a white sheet.

So they are back lit, and the needles are lit.

I later made new faceplates based at a scan of a RS4 instrument.



Its a real spaghetti-mess, but it still works just as fine.
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kb1gtt
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Re: rusEFI display

Post by kb1gtt »

How many of those pieces can you get today? What pieces did you use to make it?

My concerns with steppers is long term availability, as well as minor electrical issues causing missed steps, so wandering needle. Those RC servo's have been around for like 30 years and you'll be able to get them in 30 years. They are slower, but they have feedback, so they don't wander.
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Re: rusEFI display

Post by NickZ »

Ive done a little work on dashes, but im still along way off yet. My version uses serial data and each gauge can be daisy chained, they use 3 wires only positive, negative, 1 serial in. each gauge is given a ID with its serial positional data. 0-900 and 36 ID's 0-9 a-z. Data is sent "a300" would send Gauge "a" to about about 9 o'clock ish on the gauge.
here is a video of it working.

960
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Re: rusEFI display

Post by 960 »

kb1gtt wrote:
Sat Sep 28, 2019 11:31 pm
How many of those pieces can you get today? What pieces did you use to make it?

My concerns with steppers is long term availability, as well as minor electrical issues causing missed steps, so wandering needle. Those RC servo's have been around for like 30 years and you'll be able to get them in 30 years. They are slower, but they have feedback, so they don't wander.
These steppers are "standard" components, and are very available.

An example:

https://www.aliexpress.com/item/32793927431.html?spm=2114.12010612.0.0.2c075c5aeWdv5b

There are never any issues with these, they are used in all modern instruments.

You just run it at hard stop at start, and they never get out of position.

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kb1gtt
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Re: rusEFI display

Post by kb1gtt »

OEM's have quality control that allows for reliable assembly. We do not have that kind of control over the assembly. There are reasons why RC stuff are servos and not stepper. Also there are reasons why OEM's are stepper. It's all about a certain level of quality for minimal dollar. If you can control the assembly process you can use cheaper components.
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960
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Re: rusEFI display

Post by 960 »

kb1gtt wrote:
Sun Sep 29, 2019 4:24 pm
OEM's have quality control that allows for reliable assembly. We do not have that kind of control over the assembly. There are reasons why RC stuff are servos and not stepper. Also there are reasons why OEM's are stepper. It's all about a certain level of quality for minimal dollar. If you can control the assembly process you can use cheaper components.
The reason for that are that these steppers dont have anything near the torque a servo has.

Steppers are fast and presise, while a servo are a lot slower.
The servo has gears to slow it down, while these are made to have minimum rotating mass.
That way, they can move faster than you eyes, and stop just as fast and exact.

So in a rc, you wouldn't want anything near this speed.

They are built for this exact purpose, and works perfect for it. They are also easy to control.

So I dont see any reason for claiming a servo would work better for this. If so, there would be servos inside every instrument instead of these :-)

You should order some to play with, and you will see how good they performs..

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Re: rusEFI display

Post by 960 »

Whats the issue with assembly by the way? these are easy to place, needles fit straight on, and they takes almost no space..

https://www.xsimulator.net/community/threads/driving-diy-cluster-gauges-with-gamedash.5896/

You will find the switec x25 library here. The first that came up in a search

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kb1gtt
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Re: rusEFI display

Post by kb1gtt »

Small resistance on the electrical connection causes all sorts of issues. The thin needles can get bent and drag. Steppers are fragile that's why they are put inside a plastic box. Fast needles can also be a problem. Flutter can make the needle invisible.
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puff
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Re: rusEFI display

Post by puff »

it seems you have some prejudice against it. did you have some negative experience with stepperes in the past?
I'm not sure about longevity of servos (at least the hobby ones) in such applications.

And during one hour operation of my diy stepper-based tacho, it worked just fine at -15Cº without any flutter or issues. I used a needle made of polycarbonate, it wasn't even balanced...

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Re: rusEFI display

Post by stefanst »

I think these steppers usually self-zero during startup. You start the power to the dash and they go a few steps negative to zero against the hard stop.
The above referenced steppers are what's used in most OEM dashs. They are designed for instrument use.

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Re: rusEFI display

Post by mck1117 »

My Focus has stepper gauges (tach, speed, temp, fuel), and zeroes the gauges when you unlock the car. A normal driver will probably never see it happen.

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Re: rusEFI display

Post by stefanst »

What I don't know is how they get zeroed when you turn off the ignition. Is the dash getting constant power from the room fuse? I mean the fuel gauge can stay where it is, but all the other ones, especially the tach should probably get zeroed with shutting down ignition.

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Re: rusEFI display

Post by 960 »

stefanst wrote:
Mon Sep 30, 2019 1:39 am
What I don't know is how they get zeroed when you turn off the ignition. Is the dash getting constant power from the room fuse? I mean the fuel gauge can stay where it is, but all the other ones, especially the tach should probably get zeroed with shutting down ignition.
The instrument in your car have permanent power.

I didnt care about that when I made mine, so the temperature and tank gauge stays where I turn off the ignition.

The Tacho and speedometer goes to 0 every time, they have never got out of position.
(Actually not sure why my tachometer goes to 0, or how I did that)

When you power them, you run them all CCW against hard stop full speed.
It only takes a few microseconds.

It seems Jared has something against these steppers.
I have nothing negative to say about them. I remember I was impressed how fast and presise they was when working with them.

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Re: rusEFI display

Post by 960 »

You can also buy needles that fit straight on.

First find at search:

https://www.aliexpress.com/i/32960195068.html?spm=2114.12057483.0.0.48a6ca117VyeMD

The issues Jared describes, I dont recognize at all.
They are far from that fragile, and the speed you set yourself.

I have set the fuel and temp gauge very slow, while I tuned the tacho until I had no lag.

The flutter thing, I havent seen.

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Re: rusEFI display

Post by kb1gtt »

Yes I do not like open looped motors. Steppers are just a cheap open loop motor. I also do not see definitive design criteria. I just see people claiming OEM's do it so it's better. OEM's have different design criteria which allows them to use steppers. I think we need a more robust dash at the expense of $0.10 per needle.

The decision will ultimately be determined by the designer. I would suggest a servo design. If I get enough time I would design with a servo.
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Re: rusEFI display

Post by puff »

I would say, in my 1993 audi I have four servos driving my climate control flappers (which is off during probably half of my rides) and four steppers in dashboard (which works constantly). I had to replace pots in those servos to make climate control work, and it seems they've been repaired by previous owners, and the dashboard works just fine.
I've heard of people replacing their TPS sensors quite freqently.
Does this count as a design criteria?

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kb1gtt
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Re: rusEFI display

Post by kb1gtt »

I know poor designs that cause steppers to be replaced in a similar fashion. So no I would say that does not count for design criteria. It is likely that the POT's in the flappers were simply of poor design. AKA they used a wrong current on the wiper.

Design criteria should be something like a needle rate of ?? rot/sec, ambient temperature range ?? min and ?? max, ?? number of full cycles, cost below ?? dollars, Needle width of ?? wide, etc.

Personally I think the needles are nearly useless for rapid changes in driving. I agree a stepper is faster, but I think your eye would react to a specific rot/set, and I think that a servo is fast enough for what you eye can see. I've also seen OEM's slow down the needle to make it feel silky smooth.

How do we generate a design criteria list? Are there standards we should reference, similar how we referenced AEQ-100 for ECU stuff?
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Re: rusEFI display

Post by 960 »

I have used these steppers for several projects, including custom dash without any protective glass.

I really think you should buy some, and do some testing before you judge them.

I think you will be both impressed and surprised how well they performs.

I also think you will find them a lot more robust than the way you seem to describe them.
As long as you dont need to sit or stand at the needle, they be just fine.

Just order some and do a quick test. If you have a arduino, I have some scetches ready to go..

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