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How to connect two boards?

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bobsun

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Hello,

I would like to ask a question on board connection.

What should I do if I want to connect two boards together? One is the main IC board containing the CPU, DDR2 as well as auxiliary chips; Another is basically an extension/connector board which several (for testing) LCD displays, motors, LEDs and keyboards are connected.

The main board is a “master” which controls the extension board:
  1. The main board uses GPIO pin for controlling H-bridges on the extension board in order to control motor mounted on the extension board.
  2. The main board output video signal to LCD displays on the extension board.




Most obviously, for purpose (1) I need to make the grounds on the two boards the same, and I am considering using either a jumper wire or a connector (whatever suits) to connect the GND of the two boards together. I have never tried this before, so:
  1. Is it correct and safe? Is there any possibility for damaging the master board by current?
  2. Any recommendation on other good practices for connecting two boards?







Bob
 

andre_teprom

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A very important care is to ground external surface of connector to certify that reference GND will be the 1st net to be connected.
If you are using pin-array, take the first, and last pins grounded, due one of them will be firs connected ( assuming connecting at any inclined angle ) .

+++
 
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bobsun

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Andre,

A very important care is to ground external surface of connector to certify that reference GND will be the 1st net to be connected.
When you say "ground", do you mean "connecting to GND of either the main board or the extension board"?

due one of them will be firs connected ( assuming connecting at any inclined angle ) .+++
What do you mean by "due one of them"? Why there should be inclined angle?


Bob
 

bobsun

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marce,

What if I haven't reserved GND pins for board connection in the main board? Does this rule out the possible for using those high speed connector you showed?

For signal connection (GPIO and LCD) I did have reserved pins for connection, and connectors similar to the one at your linked address could apply.

There are some quite a few test points on the main board connecting to GND, and I am currently considering using a flexible jumper wire to connect one or a few of these test points to the GND of the extension board. Is it a good practice?


Bob
 

marce

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As a precaution I would allow for some means of connecting a very strong ground connection between the two boards, just in case!
On jobs like this I would connect ground through the connector, but also have a PTH hole so a solid bonding wire could be added if required for EMC etc. If you dont use it, no problem, its there for any problems.
 

andre_teprom

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When you say "ground", do you mean "connecting to GND of either the main board or the extension board"?

Take for example the case of DB-25 connector.
The external surface is metalic and in most applpications, is internally connected to logic GND.

What do you mean by "due one of them"? Why there should be inclined angle?

I assumed that connection between both boards would be performed manually, not by rail guide.


+++
 

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