how to hold stm32f4discovery in place?

arro239 · ‎2014-12-30

Posted on December 30, 2013 at 19:42

Is it safe to drill the f4discovery board? For example around the SWD connector or the ST logo?

I need to connect the discovery with a 10x10 expansion board I am designing. I am probably planning to have my board under the discovery so that I still have access to the LEDs and the reset button. I know that there is an option to solder my board to discovery, but that would be the last resort. So, I want to hold the boards together with more than just the pin header, so I am thinking about bolting them together, so I need a safe spot to drill the discovery board :)

ilmars · ‎2014-12-30

Posted on December 30, 2013 at 20:19

Don't even think of drilling. If you even manage to find safe spot around logo what you will do with other end of the board? Anyway you shall study

http://www.st.com/st-web-ui/static/active/en/resource/technical/layouts_and_diagrams/board_manufacturing_specification/stm32f4discovery_gerber.zip

then. F4discovery have so much pins - why you need to hold it using screws?

arro239 · ‎2014-12-30

Posted on December 30, 2013 at 21:03

Thank you for the gerber files!

I want to use the board in a car so there will be vibration. I guess even one single bolt in addition to the pin headers would help a bit?

ilmars · ‎2014-12-30

Posted on December 30, 2013 at 21:18

I guess even one single bolt would help a bit?

Single screw at one corner can make things worse. So you need two screws at least. But corner around audio jack is very busy - no place for hole. Look at f4discovery board pin layout - there's four pairs of GND pins at corners. You can ''tie'' F4 board to mainboard using wire and soldering iron. No screws to come lose :)

arro239 · ‎2014-12-30

Posted on December 30, 2013 at 21:33

So the 5.05 mm outside of PB7 and lower are pretty much free? That's the bottom-right corner. I know it's kinda on the side, I can put two smaller bolts there

And another one between the pins and SWD connector, to the left from C17&C18? Seems like like an open space too?

Technically I do not need the audio jack so if I remove the jack the would be a spot between the jack and the pins.

ilmars · ‎2014-12-30

Posted on December 30, 2013 at 21:59

If you want to use your drill - do it. I give up :) Just don't use metallic screws.

raptorhal2 · ‎2014-12-30

Posted on December 30, 2013 at 22:07

If you have the room, a simple answer is to use a hardware store electrician's plastic tie wrap around both assemblies.

You didn't identify the type of car, so we can only guess at a suitable answer. A street car or or even a hot rod style won't vibrate the assemblies apart using just the headers. A car with tire shake at launch can shake any screw loose.

Have you allowed for vibration effects on the User and Reset push buttons and on the jumper blocks ?

Cheers, Hal

arro239 · ‎2014-12-30

Posted on December 30, 2013 at 22:23

Endurance road racing car.

Great point about the reset button and the jumpers, I guess the simple answer is I should overcome my laziness and make a custom board :)

Andrew Neil · ‎2014-12-30

Posted on December 31, 2013 at 01:03

Look for something that will grip the board by the edges?

Or a board that provides proper mounting points.

raptorhal2 · ‎2014-12-30

Posted on December 31, 2013 at 01:54

I have built a few ProMod data loggers and have some sensors, connectors, enclosures and experience left over. Contact me at raptorhal@bellsouth.net if interested.

Cheers, Hal