|
I don't think he's talking about Pi - but PC main boards.
Without getting into a long long long discussion, the reason "boards" are laid out the way they are is due to standards. Standards - a group of people that decide we shalt do it this way. There are many standards. The reason it's good to follow standards is to allow to sell your product.
Let's talk PC boards. They need to allow Intel and AMD to drop processors into them. What about PC cases? Well, the boards and the PC cases better agree. It goes on an on. List: CPU requirements, where to put the PCI, PCI Express, SATA connectors, agreed upon power connectors.
Industry groups got together to create consortiums so all progress.
Charlie Gilley
“They who can give up essential liberty to obtain a little temporary safety deserve neither liberty nor safety.” BF, 1759
Has never been more appropriate.
|
|
|
|
|
You see such headers (male) and sockets (female) both on PC main boards, Raspberry Pi, Arduiono and lots of other places.
As you say: There must be an agreement, for lots of things. That agreement is usually identified by a name or standard number, pointing to a defining document.
I was hoping to find a pointer to such a defining document for these headers.
E.g. Wikipedia: Pin header[^] refers to various header pitches and a couple pin cross sections - but from which document are are these values taken? What else is found in that document?
|
|
|
|
|
I have always found company's like RS / Farnell (Newark, Element 14)'s Web sites quite good if you look for Pin Headers they all the spec's you could want. Molex is a name for a family/ brand, also Pheonix is a another brand name (very resilant, green coloured!). As to voltage the data sheets can give better guidance than I (9 Volts is safe, 5 is normal). I have always kept to around 50mA, the Pheonix I have use for 4-20 system with no problem. Phoenix tend to have threaded bolt as attachment, Molex I have seen with threaded bolts and clips. For use figures have a look at 'mating cycles' (higher the better!)
|
|
|
|
|
Could you provide a link to those web sides with the specs?
It is easy to find 'hearsay', things that 'everyone knows that' so and so. (And essentially, I have known the connectors at that level for many years!)
Finding complete, hard specs is quite a bit more difficult!
|
|
|
|
|
I was surprised how tricky it was/is to find the info - iI believe the pin spacing is 2mm in each direction, and Farnell have info on a 20-pin, 2mm IDC receptacle: 89361-720LF Amphenol Communications Solutions, IDC Connector, IDC Receptacle, Female | Farnell UK[^]
The data sheet for that shows it is made by Amphenol, drawing number 83951, title '2.00 mm IDC'. It seems obvious that this must be an industry-agreed design (dimensions, at least), or nothing would fit together, but where the spec for such standards may be found is another matter.
|
|
|
|
|
Generally they are set by ISO International Standards Organisation. ISO has a standard for it, look for someone muttering 'ISO 909 part B' chances are they are Quality Inspectors panicing! 
|
|
|
|
|
|
|
Oh boy. As you would expect, there's lots of variables that come into play. The pin and plug have to meet the needs of the voltage and amperage that they will carry. Pin spacing will also be affected by the size of the traces and their spacing that the pins will attach to on the circuit board. Beyond that, it comes down to the preferences of the manufacturer.
|
|
|
|
|
The only "standards" for the most part are set by the specific manufacturer, for a specific product line. There literally thousands of product lines in current use, and tens of thousands more historic lines that are no longer made. As you can see here at a popular parts supplier in the US:
https://www.digikey.com/en/products/category/connectors-interconnects/20
there are over 5 million separate results searching for "connector". That is FAR from a comprehensive list. There are hard metric, hard English pin size/spacing's and a few that are "both" meaning close to an even mm dimension and an English dimension that is an even fraction of an inch. Sizes range from so tiny you cant see the individual pins to huge (for high power AC distribution for example), depending on application. By convention the headers on mother boards are .1" spacing (both ways if multiple rows). The shroud (with or without key slot) is optional and often omitted as a cost saving measure. these are a significant improvement over edge card connections, but still not exactly "safe". The pins are always square and "tinned (coated or plated with metals similar in appearance and possibly composition to solder)" or gold plated, which effects reliability, cost, and capability (voltage and current specs). The mating female connectors come in a variety of sizes, and internal construction in turn effecting cost and performance. MOST of an EE's job in the modern world is about selecting parts for availability, spec, cost, etc. EVERYTHING is tradeoffs: cost vs performance vs thermal management vs ease of use/manufacture etc. etc.
Every manufacturer thinks their products are superior - and maybe they are in some applications. Nothing works well everywhere. Some (like 0.1" pitch headers) are more common than others. Even in specialized applications like RF there are dozens of kinds in common use, all have their pluses and minuses. And a hundred more that are very uncommon and found only in certain applications or in certain countries products.
Using the latest technology to create tomorrows problems today.
|
|
|
|
|
I believe the connector variety you're looking for was originally manufactured by Dupont. They are called Dupont connectors these days.
|
|
|
|
|
One of the better innovations I've seen in PC building was what ASUS calls a Q-connector.
You don't futz with all the connections directly on the board nor the manual to map them. They provide a block that covers the 12-16 pins all at once. You plug stuff into the block where each pin is labelled, then put the whole block on the board.
I'd guess there'd be something of a market for that sort of thing in a bunch of other hardware too.
|
|
|
|
|
More convention than standard. There are standard connector types, most started as some manufacturers spec, 0.1" square spacing double row the most common, usually square pins, ( this is mostly a manufacturing consideration, especially related to how the female contacts are made - stamped from thin sheet), but 0.157 (? that's from foggy memory ) isn't that rare, and the dreaded 0.2mm ones are used when some bright eyes wants to save a tiny bit of space.
Higher power connectors usually mean larger pins, wider spacing, often round pins ( to match more robust machined sockets ).
The other convention, that Rasp Pi violates in the name of price, is that power flows out of female connectors.
( Yeah, I blew up one Pi when the pins touched a piece of EMT. )
|
|
|
|
|
Thanks to everyone who replied to my request.
I guess some of you wonder why I asked the question, and was so eager about the formal standard. I'll tell:
A while ago, I got so frustrated over the enormous numbers of 'standards' I (have to) relate to (ref. Tanenbaum: The good thing about standards ), that I sat down to make survey of 'Standards I Have Met'. I went though a large number of areas, from storage media to lightbulb sockets to battery cells to SCSI plugs (my equipment used 8 different ones - but there is said to be 14 ones in use) before I ditched SCSI), USB plugs (one more now, and I will be tempted to let USB go the same way as SCSI), ... I also made sections of software standards I have tried to adhere to, such as document formats, character encodings, binary numeric formats etc.
In almost every every, there were so many 'standards' that it turned my frustration into fascination. I never thought there would be that many! So I decided to try to make the list as complete as possible. I took a look at my PC mainboard to see which I had forgtten (I put my PCs together from separate parts, so I do relate to the 'standards'), and asked about the standard for these front panel(++) headers to get it into my list. I guess they go into my list as something like 'Unidentified standard(??) #27'
|
|
|
|
|
Back in my younger days we had these same pin's on the underside of the BBC Micro, and the sockets, slots variations on devices etc.
The standard they where known by, along with the ribbon cables that attached them where
"IDC Connectors"
Sometimes single row, sometimes double, some where male, some where female, some where 10 pins long, others where 20 pins or more, then there was the flat ribbon cables and the square plugs that went on the end, we just called all of them by the same name.
These days, I have a crimping tool and pins/sockets rows, double blocks, 1x2 2x1, 2x2, 4x2 and so on...
Those wires and connectors (According to my crimp tool manual) are called
"Dupont Connectors"
Dunno if that's the info your looking for.
Shawty
|
|
|
|
|
|
I'll stick with software development; sitting around drinking coffee and not having to track down who misplaced my wrench.
|
|
|
|
|
And it's really difficult to skin your knuckles on a sharp* bit of code!
* Or even a C# bit of code.
"I have no idea what I did, but I'm taking full credit for it." - ThisOldTony
"Common sense is so rare these days, it should be classified as a super power" - Random T-shirt
AntiTwitter: @DalekDave is now a follower!
|
|
|
|
|
Depends on how hard you bang your keyboard.
Give me coffee to change the things I can and wine for those I can not!
PartsBin an Electronics Part Organizer - An updated version available! JaxCoder.com
Latest Article: Simon Says, A Child's Game
|
|
|
|
|
Come, come now, there are young people watching. 
|
|
|
|
|
Richard MacCutchan wrote: Come, come now, there are young people watching.
Uhh...I'm pretty sure there are no young people here. 
|
|
|
|
|
Whaddya sayin'? I only turn 62 next week. That's young enough.
Software Zen: delete this;
|
|
|
|
|
I'm young in that case... 50 here
|
|
|
|
|
True story: Back when I was in college I worked at Wright-Patterson Air Force Base on a VAX-11/780, which used DEC VT100 terminals.
I broke a VT100 keyboard by banging on it too hard.
Software Zen: delete this;
|
|
|
|
|
I've hit mine pretty hard, in the past but never broke one.
Give me coffee to change the things I can and wine for those I can not!
PartsBin an Electronics Part Organizer - An updated version available! JaxCoder.com
Latest Article: Simon Says, A Child's Game
|
|
|
|
|
General 
News 
Suggestion 
Question 
Bug 
Answer 
Joke 
Praise 
Rant 
Admin 
Submit an article or tip
