Stackable modules?

[krypton_john]

Hi All,

I really like the idea of using communicating picaxes to split the logical workload into distinct functions. As an example, a picaxe as an RF comms processor, another as a data collector, another as a user interface processor etc all given directions by a master controller. Each can be configured with a device id and they can communicate with eachother by various methods discussed in this forum.

But they still need to be connected by a common buss. It would be neat if the modules could be stuck together like lego bricks. All that is required is to have a connector with that is a socket on one side and pins on the other side that pass through and solder onto the board. A pin header and socket in one, with pins long enough to pass through the board and mate to the next board.

So next time you are building a robot you just plug together a controller module, a motor driver module, an RF module, a death ray module etc and away you go.

So... anyone know of a suitable connector?

 

[moxhamj]

There are many solutions:
You could put sockets on the board below and header pins on the board above eg http://cgi.ebay.com.au/50X-Male-25X-Female-40-Pin-Square-Single-Row-Header_W0QQitemZ320254393696QQihZ011QQcategoryZ109438QQcmdZViewItemQQ_trksidZp1713.m153.l1262

You can use D9 plugs - I have some boards and with the square board two sides have female plugs and two have male - the boards join together side by side.

You can stack the boards one above the other with mounting posts and not join the boards to each other with header pins, but rather have a 40 pin header on each board and a 40 way ribbon cable between each board. 40way ribbon cable is the same one used to connect hard drives to PCs so they are a mass produced item. Can be bought for less than a $1, or salvaged for free from old computers.

You can use the sockets and then to get longer pins can use wire wrap pins - they are longer than standard header pins. It depends on the tallest component on the board.


The code does end up rather larger than one would expect - I'm filling an 18X at the moment though this does include LCD display code as well.

For robotics I guess the idea is to build things up from simple to complex eg http://en.wikipedia.org/wiki/Subsumption_architecture

I'm actively working on this at the moment but it isn't ready for publication yet.

 

[hippy]

Standard 0.1" right angle headers sockets and pins would let them extend side by side.

Best suited for 14M/20M.

 

[krypton_john]

Drac, If I understand you correctly it won't work as the sockets and pins cannot line up. Therefore a stacked set of like sized boards would be a rhombus instead of a rectangle. The pins of the socket need to be long and forum the pins of the plug. Kind of a wire-wrap socket but not that long.

The ribbon cable would work, but not nearly as neat and convenient.

 

[krypton_john]

Hi Hippy

Yes that would work, but I'm looking for something more compact and mechanically rigid. If the boards were say 70x30 you could stack 5 and it would still fit in a can.

 

[BCJKiwi]

It seems these things are called 'Stack Through Connectors'.
They are not common as they don't work well on autoassmbly/PCB construction with their long pins and they can't be wave soldered.

Hence they are rare and expensive.

Search www for 'stack through PCB connector'

 

[moxhamj]

We have ways of making the pins line up! Just have two rows - row A and row B. Run them in parallel maybe 0.2" apart. Join the pins up in pairs from A to B. Board 1 to 2 uses row A, then board 2-3 uses B then 3-4 uses A. And I would split the rows so half on one side of the board and half on the other, so the board ends up mechanically stable. It would be a pain to wire up with point to point wiring but easy on a PCB.

 

[krypton_john]

Nice one, BJCK,

One such search leand me to PC104 connectors, and I think that PC104 was what made me subliminally think of stacking Picaxe based modules.

Looksl like PC104 connectors are only $11, but have far too many pins. Possibly they could be cut down into lots of little connectors.

 

[krypton_john]

Check this - https://www.kiwacandirect.com/shop/product_info.php?products_id=303

PIC-32.... so close!

 

[krypton_john]

We have ways of making the pins line up!

Could you now say that with a German accent, please?

 

[BCJKiwi]

What about these?
http://www.arieselec.com/products/12009.pdf

Kiwacan have a through connection section on their boards and used to sell a part called;
Kiwacan KPIC-STACK-KIT
but couldn't find it anywhere on their website(s).

Well Dr. not quite lining up but alternating, which means they are not universally interchangeable (unless I've not thought it through sufficiently).

 

[moxhamj]

Yes, ok, not quite universal. I've gone for the board with a D9 on each side and true RS232. It is a bit wasteful to turn a signal into RS232 then back to TTL when the boards are right next to each other but RS232 drivers/receivers (Max232) have another big advantage in that they can handle a wide range of input voltages. So if you accidentally plugged an input to an output, or put -10V on a pin or shorted a pin it won't zap the picaxe. So my boards don't go up, they sort of spread out like a domino game. It is quite fun watching messages propogate through the system, and it is great to have boards that can be plugged together in any physical layout and the messages will get to their destination.

Boards could easily be stacked one on the other. Just use a short piece of 9 wire ribbon cable and a male to female D9. I've been using IDC D9 plugs - only a bit more expensive than solder, but not having to solder makes wiring up plugs so quick. Put in the cable, stick the plug in the vice and squeeze.

I'm not sure how stable a stack of 5 PCBs would be if only held together with plugs and sockets. I think PCB mouting posts would be a lot stronger, especially for robots.

 

[hippy]

Pass-through stackable connectors do have the problem that what comes in from the bottom goes out the top, so great for bus systems or where one module routes its outputs to particular pins, but not good for daisy-chaining modules.

Another option is to go for a backplane system using 2xN connectors so the signals run left to right on the backplane, up a connector, into board and out, down the other side of connector and up the next. Boards with contacts on each side should work ( like ISA cards ) and it should be possible with IDC plugs and sockets. Would even work on strip-board with some cutting of tracks and link wires.