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For discussion of Speeduino compatible boards designed / built by other members of the forum and for guidance around making such a board
By Kalns
#46742
Hello to everyone. My appologies if this question has been here answered, link to discussion would be nice.

I am in process of designing my own board based on pazi work and others.. I am developing a board with enclosure and 2x24pin plugs off aliexpress, generaly used in LPG applications.. 4cylinder sequential injection and ignition using mega 2560pro board...

Anyway, back to the topic.

I am wondering, what is correct way to design sensor ground ? I mean, does it is thesame as power ground, or is it seperated or connected like with a shunt resistor or something? Is there any filtering inbetween those two grounds on the board ?
I do understand that sensors must have a good ground connection in order to get correct reading of the sensors.
By LPG2CV
#46753
if your using lpg injectors, beware the are often low impedance, and most boards are designed for high impedance.

if you download the zip file from github, there is a good schematic there of various parts of the circuits that may help you.
By LPG2CV
#46762
No, nothing special.

You would do better if you could run them back to the ECU though.

CLT and Iat sensors work based on resistance. Therefore, any unintentional resistance you add to the ground, will skew the result.

TPS and Hall Effect sensors require three wires each. The ground and live wires will incur less interference if installed as a twisted pair.

If your wiring is already in place, then just try it. :)
User avatar
By PSIG
#46771
@Kalns - like most ECMs, Speeduino does not use "isolated" grounds. Instead, steps are taken to avoid voltage offsets and ground loops that affect sensor readings. How you ground sensors-vs-power is important in order to avoid these issues, making non-isolated grounds usable for most applications. I will be lazy here and let Andy Wyatt explain it, either by article, or by video. Put your foil hat on (but not aluminum foil). ;)

https://youtu.be/ZTDsm6b69Lk
By Kalns
#46785
Thanks for answers, have a good day.

I have seen almost all Andys videos, I realy like adaptronic modular aproach.. and also I have installed couple of VEMS ecus, its the first time designing my own board, that is why i am asking this, since there is no clarification what happens on pins on other side of the plug.
User avatar
By PSIG
#46802
The schematics and PCB trace images (in the download packages or on GitHub) for your board type can show you what's going-on behind the connectors.

My first rule is to use one ground point for sensors only — no high-current or noisy stuff on that point. I look for a "quieter" point, separated from noisy I/O and solidly on the ground plane. For example on most v0.4.x, I'll use pin 23 with these attributes, which also provides ground near the proto area, so using that one helps to maintain grounds typically also used for custom sensor inputs and low-current stuff. These preferences might be splitting hairs, but I'll take every advantage I can, and usually avoid issues along the way. You can use your own similar 'rules' in your board design.

Likewise, you can provide multiple power-ground points for multiple ground wires to your star ground, likely on the engine block. Whatever you plan and design, you can inform your users to follow your wiring guidelines in order to take best advantage of your design features. Nothing like more success through planning. In-spite of most Speeduino designs not guiding users to wire in certain ways, the number of noise and voltage offset issues is relatively low, indicating it doesn't take much to avoid problems in this area. Do your thing! 8-)

David
By JHolland
#46818
The sensor grounds and power ground are connected but the return paths should be seperated. generally you should keep all the analogue on one side of the board and the power on the other side. The important part is to try to ensure that any ground connection can flow straight back to the ground pin without. Ford have published one of the best documents on PCB layout here: https://www.fordemc.com/docs/Design_Guide.htm
Whatever you do don't copy the 0.4.3 design because its truly terrible.
By Kalns
#46865
I think i got my head around this.

Yes i know that power circuits should be seperated, I have thesame case Josh will be using for Drop bear, today found out this :)
All sensor inputs are on one connector and outputs are on other.
Also I`ll be using 14point7 slc oem wb02 controler.

Realy hope it will work :D

Now I am trying to finish crank / cam circuit and optimise all circuit in general where posible.
Idealy i would like to use smd IGBT replacement, if anyone knows part number, i would appritiate.
PS. if anyone have some hard suggestions what should i do diffrent then please, welcome :)

pps should ground points on the board be routed to each other, or not if i leve everything filled with copper ?
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