memory plug v2 problem « Jee Labs Talk

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memory plug v2 problem

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hamlet

Hello, I finally got to explore JeeStuff...
First the memory plug, and after few hours of wrestling and discoveries, it doesn't work !
So I have a few questions to try to find out why it's not working :
- Is it normal that DIO and GND are electrically linked ? I tried to find the problem and couldn't... It's my first SMD soldering ever, and really ugly work, but then I can't find anything between GND and DIO. And I don't remember testing this before...
- Can short circuits occurs through the protective layer after it being burnt ? I pretty much burnt the place around the DIO pin (bottom side) and it's surrounded by GND, so maybe it could be that...
- If this is normal, why do eemem.pde always return 0 ? All seems to work well (as long as I put the plug in the good Port) except that it keeps printing 0... I tried (as said in http://talk.jeelabs.net/topic/63 ) to see the result of send(), it's 1 !
- Should eemem.pde (as found in http://jeelabs.org/view/libraries/Ports/examples/eemem/) work with mp2 and M24M01 ?
- Is http://www.st.com/stonline/products/literature/ds/12943.pdf the good documentation for the M24M01 you sell ? If so, I can only see two address pins... And last bit seems to enable writing, I tried that with no luck...
I hope I'm not too messy and that you'll be able to help me out ! Regards,

Posted 27/05/2010 17:56:19
jcw
> Is it normal that DIO and GND are electrically linked ?
No. There's a short somewhere. These can be very hard to find. Remove solder everywhere - the ground plane is sometimes not 100% covered with the blue soldermask.
> Can short circuits occurs through the protective layer
I don't think soldering heat will damage the solder mask, but heat and scratching probably can.
Get some solder wick and remove as much solder as you can. It works well. Keep removing until the short is gone.
> why do eemem.pde always return 0
It's probably the same as when you remove the plug. There is no test, but you can add one:
```
    if (eemem.isPresent()) Serial.println("found!");
```
> work with mp2 and M24M01 ?
Yes.
> Is the good documentation
Yes.
Look at the schematic - - Write control is not connected, that means the chip allows both reading and writing.
Make sure you are using the correct chip position and I2C address (0x50..0x57) - see , which you probably already know.
You could email me photo's of both sides of the plug (or link them here), maybe I can see something.
Posted 27/05/2010 19:46:40
hamlet

>>why do eemem.pde always return 0
>It's probably the same as when you remove the plug. There is no test, but you can add one: if (eemem.isPresent()) Serial.println("found!");
Actually when there is no plug in, the returned value is 255 !
And your test is working well... :-(
> Get some solder wick and remove as much solder as you can. It works well. Keep removing until the short is gone.
I'll do that tomorrow...
> Look at the schematic
Great ! What I did not understand is that you linked DU (Don't Use) to GND... But now it's clearer !
> Make sure you are using the correct chip position
I put them the same way as the one you did...
Could they be burned or something ? My iron is not gentle, and I needed several tries... I wish I had tested yours before launching myself in SMD, but did not want to solder the header before the chips.
> You could email me photo
Doing that.

Posted 27/05/2010 21:50:30
hamlet

> No. There's a short somewhere. These can be very hard to find.
Found it ! :-D
Actually while preparing photos for you...
I'll post before/after photos tomorrow.
And the eemem test seems to work perfectly, and I can go to sleep with my mind at peace !
Thanks a lot.

Posted 27/05/2010 22:13:58
hamlet

That is before :
And after a little bit of cleaning it works :
Actually it is was not visible with naked eyes, and barely visible with my cheap magnifier... But the camear I used is great ! :-)

Posted 28/05/2010 09:25:09
jcw

Try to set your soldering iron slightly hotter. That will cause the solder to be more liquid, and then surface tension will keep it more evenly pulled together.
Also, try to use less solder. I find that this is much easier with a flux pen. Ideally, the solder will flow right between the pin and the pad, and won't even form a drop on top of the pin.

Posted 28/05/2010 10:40:13
jcw

Here's an example:
Not as clear or as good as I wanted, but maybe it helps anyway.

Posted 28/05/2010 10:44:22
hamlet

I see your point... I will try to be more careful next time !
Also for the hotter iron, it's already burning the hand holding it ! I need to make a kind of protection I think...

Posted 28/05/2010 11:12:59
bvwelch

Nice. Any specific flux pen? I'll hunt around on your web site to see if you have any tips/tricks for SMT work. I'm looking to upgrade my equipment and there is a bewildering mix of gadgets out there. A beginner's list for a modest station would be welcome.

Posted 28/05/2010 11:14:46
jcw

I'm using Farnell part# 876732. Lasts much longer than I expected. It leaves a slightly dull residue, but since it's "no clean" flux, I usually just leave it on.
I was thinking of writing a weblog post on this topic. Got quite a few posts in the queue right now, so it will take a while to show up.
@hamlet - Consider getting a better soldering iron. I used the same (fairly good, but low-cost) 15W Weller for ages, but the new setup is just great. Much smaller, much lighter, much thinner, MUCH faster heat-up, and ... much cooler, even after hours of use!
Ok. Weblog post coming up. Everyone has his preferences, but the least I can do is to describe mine.

Posted 28/05/2010 11:34:02