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Author Topic: Designing connector between two PCBS - similar to SD card  (Read 821 times)
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Hi Everone

I would like your opinions & ideas on a problem I am having.

I am currently designing a prototyping platform (everything is still very beta, but I might post some general info on the project in a separate thread.) The system is modular, and basically consists of a motherboard, with multiple modules which you can connect to it. There are ~ 11 - 15 signals (as I said, things are still beta.) which need to be connected between a module and the motherboard. Currently we are connecting things with regular pins, like the Arduino shields. However, the modules are so small (33mm x 33mm, smd components), that almost 30% of their bulk is created by these connectors. I am currently looking for alternate methods of connecting them.

Does anyone have any suggestions?

I really like the way SD cards connect. I was thinking that it might be able to create a similar system. Does anyone know the name of the little connectors in the SD card connector? (I attached an image in which I circled what I am talking about.) I am speculating, that if you could get those individually, that you could create your own sd-card-style connector. (this also has the benefit of ensuring that power connects before logic level signals connect, which we don't have at the time.)

Alternately the MMCplus has a layout that would work for our system. However, I was unable to find anyone offering connectors for MMCplus. I am either using the wrong search-term or... they are no longer being fabricated or they are some ultra secret licence? (I was searching on alibaba.com and similar sites)

here is a picture of what I am talking about:

Thoughts and Ideas would be appreciated... and if someone knows the name for that tiny part I am looking for, that would help me heaps as well.

Thanks

p.


* this.jpg (48.68 KB, 362x331 - viewed 10 times.)
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Could you reduce the number of pins dramatically by using something like spi?
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www.jst.com carries whole lines of small connectors. Browse here
http://www.jst.com/home21.html
Here's a pic with 1.5mm pitch connectors I am working on now.
The RF module plugs into a header with 0.05" spacing.


* RX-board-pic.JPG (2157.77 KB, 2606x2530 - viewed 14 times.)
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Thanks crossroads. This is going in the right direction. Browsing their website now.

Does anyone know what connector they use for the mama-shield?
http://www.seeedstudio.com/depot/mama-shield-p-731.html

@bill - pin number is determined by a bunch of factors - we need some parallel communication and have various power options. We can reduce by a couple of pins, but that would not change the initial problem.
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This I like: http://www.jst-mfg.com/product/pdf/eng/eDM-72P.pdf
However, I need it to be about half the size, and I only need 25% of the pins.

Other alternative is this guy: http://www.jst-mfg.com/product/pdf/eng/eJMC.pdf

Still open for other suggestions.
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If you put a couple of those SCG connectors from JST side-by-side, you could have a dozen contacts in a small space.

But beware of attempts to "hot-plug" in that configuration, because you'd have contacts sliding past things they shouldn't be connected to.

I generally don't like "push-push" SD sockets in embedded systems: too much chance for shock or vibration to pop something loose.  If you go with SD,  I'd suggest looking for the non-spring-loaded kind used in many USB card readers.
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I'm just the opposite - I like the push-push for SD.
My Sony Vaio has that, works great. So does my Canon camera. I pop the card back & forth all the time for pictures, way faster than downloading via cable. Also does not use up battery.
When it's clicked in, its in.

My wife's HP does not - have to yank the card out. Always awkward.

Were we talking uSD also? Have not seen anything but push-push for circuit cards. Push/pull in uSD/SD adapter only.
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Designing & building electrical circuits for over 25 years. Check out the ATMega1284P based Bobuino and other '328P & '1284P creations & offerings at  www.crossroadsfencing.com/BobuinoRev17.
Arduino for Teens available at Amazon.com.

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