Connector considerations

[GrowlingandBiffo]

Connectors are always the bug bear of leccy stuff, but try to think of it as a mechatronic interface.

MS used a computer printer plug cos it was cheap and available when the project stated and then made it into production.

Much defence of its use was made by B&G to justify its continued use; however they are now back tracking and saying the AMPseal connector is now good, which at about £10 is not expensive, but difficult to buy off the shelf. The Mini MS V2.5 uses this. http://www.mini-ms.com/

Bosch also makes a good plug, and AMP make a cheaper equivalent, which VEMS use.

The cheapest way is to recycle and use one from a dead car, which will coast £10 to £20 dependant on scrap yard. For this you get a nice cast aluminium case, which you can fit your PCB of choice, and make all your connections inside by soldering wires, which is not so good, or making your PCB suit the pin configuration. You can then wire in the cut off tails into you engine. This could be called plug and play.

A modern car, made in the last 12 years, will have an OBD2 connector, and you can then utilise the 3 wires and mod an OBD2 to serial for your lap top, and programming will be quite simple easy and you keep a neat installation.

If you really want a new ECU case and connector try a Cinch Modice for about £25 from Farnells, however you will need an extraction tool, as they are tamper proof, and sealed to IP69K, and OE on John Deere… http://www.cinch.com/index.cinch

A comment on copying in the early part of the thread.

MS started as an Open Source project, as did AVR, and they made every thing freely available until the greed factor kicked in. This fact would severely weaken their defence of there IP. Their legal advisor will tell them this. They also do not own any patents that are enforceable in the UK under English, Scottish or Euro law.

This covers both hardware and software.

To make matters worse for them, there are other suppliers of software which will run on there hardware platform, not to mention the fact that their are alternative hardware suppliers, that can use there software. Common sense will tell you that they have no control.
Power is nothing with out control.

When PC’s were first “invented” they were soon reverse engineered, quite legally thus the march of the clones, and the term IBM Compatible came in to modern usage.

As regard ECU’s DTA have not sued KMS, whom copied (allegedly) their ECU when DTA stopped supplying them.

The above is purely the legal position not the moral.
Morality is a personal thing, like making illegal copies DVD and CD’s, or using a cracked version of Microsoft Windows…

Keep up the good work one and all..

[Fred]

Perhaps a better solution is to have wire lengths that solder directly to the PCB and after 12" or so use a harness connector. Those that want water proof, can glop the entire PCB (or put int in a box, and clop just the wires), but those that don't can simply leave it in a box. That way you can run fat wires directly where needed, and little signal wires can keep their distance.

This is an AWESOME idea that I really like! Good thinking!! Thanks for posting it up, perhaps it will spark some discussion of good inline designs?

Fred.

[thebigmacd]

Perhaps a better solution is to have wire lengths that solder directly to the PCB and after 12" or so use a harness connector. Those that want water proof, can glop the entire PCB (or put int in a box, and clop just the wires), but those that don't can simply leave it in a box. That way you can run fat wires directly where needed, and little signal wires can keep their distance.

This is an AWESOME idea that I really like! Good thinking!! Thanks for posting it up, perhaps it will spark some discussion of good inline designs?

Fred.

I like this idea too, although there has to be a better way of connecting wires other than soldering them directly into pads. I know in my industry they use stake-on spade connectors for everything. High current capacity and every automotive or fastener place has loads of them (the wire-side connectors anyway) in stock.

See here: http://www.toby.co.uk/content/catalogue ... ategory=26

[AbeFM]

Oh god I'm so not a fan of glueing wires to the board. I've done that. And I've had my MS apart every 35 minutes since I put it in. Glue is a big pain to deal with.

And connectors, for all the cases where you can say they don't work, there are a thousand where they do.

Mazda, Ford, Mercedes.... Pick any car company you'd like, and show me how they make a million cars a year and they don't have connectors.

Connectors make sense, even on cars where they don't expect them to be taken apart. If you want to get an automotive-like connector, I wouldn't argue.


But for current, decent DB connectors can have 3, even 5 amps per pin. They are generic, easy to find, low cost, and don't have issues. I've had my MS unplugged countless times, and the connector is the one thing that hasn't given me issues - all my concerns notwithstanding.


I'm pretty surprised about the spade connectors! I have issues with them all the time. They are somewhat hard to get right on the other end - the wire-to-spade connection is very problematic.
I think they are good for something you're not going to plug-and-unplug... I see them in lap power supplies, etc.... But I wouldn't use it in a car.

[jharvey]

I like this idea too, although there has to be a better way of connecting wires other than soldering them directly into pads. I know in my industry they use stake-on spade connectors for everything. High current capacity and every automotive or fastener place has loads of them (the wire-side connectors anyway) in stock.

I like and dislike the suggested spade connector(s). I like the ability to disconnect wires, I don't like the need for thru hole. Thru hole increases cost, so I'd kind of like to keep that minimal, and you really need thru hole for strength on those connectors. Perhaps a compromise is good for this, adding holes so you can put on the connector(s), but attempt to attach everything from one point. That way if you want less chance of mechanical failure, you can solder the wire directly. Or if your doing lots of proto-work then you can have the quick disconnect. All while keeping required hole drilling to a min. Basically it's OK to make a via, but don't use it as a via.

[Fred]

For the record my ms2 already has a wires with inline plug solution on it for COP use. about 10" of wire and then a plug. It works very nicely and is solid as hell. Ironically, the wires are surface mounted, but just because it was a hack to add COP to MS really. Either way, I like it, and hadn't thought of it for the main loom. However, I can't think of an easy to find inline with anywhere like enough pins :-(

Fred.

[jharvey]

Some other benefits include scalability. If you don't have a connection, you don't need to put it in. My snow blower isn't going to use 37 pins. However, I'm also sure there are folks that need more then 37 pins.

Some other thoughts, the power and inductive loaded devices should have a connector that snaps shut, well actually it's best that all connections have a snap. Not something that is held with screws, or other method that can allow for a not full contact connection. For example, with the DB series connector, if you got a chunk of dirt, debris, ect in on of the holes, then you tighten down the screws, there is till a chance that you might have a weak connection from not having full penatration. Not to mention the screws can loosen from vibration, overtorquing, ect and allow the connector to come partly apart, also causing a weak connection. That's quite important on inductive loads.

The harness connector should also probably be water tight.

Also, also, it should have solder versions as well as crimp versions.

I guess I should pick up the digikey catalog and start thumbing through the connector sections.

[toalan]

I actually like the IDC connector as it would be easiest to make an adapter board for them so you can use a more expensive connector if you want. It is easy to run an IDC connector to a breadboard for experimentation. There are also DB connectors that accept an IDC ribbon cable.

[GrowlingandBiffo]

Some other benefits include scalability. If you don't have a connection, you don't need to put it in. My snow blower isn't going to use 37 pins. However, I'm also sure there are folks that need more then 37 pins.

Some other thoughts, the power and inductive loaded devices should have a connector that snaps shut, well actually it's best that all connections have a snap. Not something that is held with screws, or other method that can allow for a not full contact connection. For example, with the DB series connector, if you got a chunk of dirt, debris, ect in on of the holes, then you tighten down the screws, there is till a chance that you might have a weak connection from not having full penatration. Not to mention the screws can loosen from vibration, overtorquing, ect and allow the connector to come partly apart, also causing a weak connection. That's quite important on inductive loads.

The harness connector should also probably be water tight.

Also, also, it should have solder versions as well as crimp versions.

I guess I should pick up the digikey catalog and start thumbing through the connector sections.

At risk of some duplication and to save yourself time a 36 pin AMPseal, is the easiest/cheapest, the ultimate cheapest is the Econoseal, as uses in VEMS and MEMS but the bestest is the SuperSeal as used by Motec. think Fred posted the Dataspares.com link,
http://www.dataspares.com/36way.html

whom have some of these always in stock, if you are UK based, very helpful and lost of stuff in the back, not on the web site, quite a few distributors in the US of A, if you search the Tyco site, or the ultimate is to phone them as "trade" and they will send you half a doz as free samples for your project, if you chat them up nice. If you need more than 36, just add a 23pin AMPseal.

A complete alternative is the Bosch 55 pin, that Tyco make a pattern equivalent, or just go down to the scrap/wrecking/breaking yard, and find a car with same. However if you are going to this extent, they will also give you the ECU case, so this is what you can mount you project in, which would then be good for a plug and play for this model. Magneti Marelli also does same in Lancia Fiat, Peugeot and Citroen ECT

For a new looking OE spec use the Cinch Modice case or just the connetors

http://www.cinch.com/view_news.cinch?pr_id=11

[Fred]

I actually like the IDC connector as it would be easiest to make an adapter board for them so you can use a more expensive connector if you want. It is easy to run an IDC connector to a breadboard for experimentation. There are also DB connectors that accept an IDC ribbon cable.

That's also a damn good idea! In fact if the board(s) were setup for that, it would also work with Jareds wires from board idea too with no changes. Considering the total and utter disagreement about connectors from all corners, maybe this is the best way to go?

Good post Biffo.

The more discussion on this the better, at some stage we will work out what we want to do for out base spec DIY share with the world version one KISS board, post that, this thread will be a good reference for anyone else designing a board for FreeEMS privately or commercially.

Fred.