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1  Community / Bar Sport / Re: Name of connectors on SMD modules on: July 26, 2014, 11:32:06 pm
I tried that, but as far as I can tell, SparkFun does not have any products like that. As in, they do carry those products, but they are produced by third parties, so there is no Eagle file for them.

It seems to be quite a standard practice though. I wonder if they literally just put vias there and then cut them in half? I'd like to design a board like that, potentially for manufacturing at a low volume, but not sure how to go about it. I was hoping to find an eagle part, but I don't even know how to start looking for it.

The idea is to design something with a tiny footprint, which you can just plop into your pcb. Well. Like the two modules I linked to.

Any thoughts?

EDIT: Ok, searching for 'plated half holes' seems to be getting me somewhere. Thanks for sharing that but of common sense, crossroads.

EDIT2: Apparently this is also referred to as castellation and appears to commonly be done by placing vias on the edge of the pcb, so that half of the via is off the board, as crossroads pointed out.
2  Community / Bar Sport / Name of connectors on SMD modules on: July 26, 2014, 11:17:47 pm

Hi Everone

I have a quick question. I can't figure out what the connectors on SMD modules are called. Like the ones on here:

or on here:

Does anyone know what they are called? Does anyone know if there are eagle parts available which I can use in my own designs?


3  Community / Bar Sport / Re: Arduino working at 3.3volts on: February 04, 2014, 12:42:14 pm
please. I take pride in my work. I do not produce crows nests :-D

4  Community / Bar Sport / Re: Various items of interest on: February 03, 2014, 07:54:44 pm
Digikey amazes me. If I order there before 8pm (my local time), Its usually on my desk by ~11am the next day. Thats 2100km, fastest rout. If I add all the intermediate destinations to the map its more like 2700km. It does all of that in 15 hours.

Assuming that the package leaves the moment I place the order, and it spends zero time in customs, that means that the package is travelling at an average speed of 180km/h.

That just blows my mind.  

EDIT: Thanks for those slides. Whoever does DigiKeys logistics is a genius.
5  Community / Bar Sport / Re: smd ZIF? on: February 03, 2014, 07:47:26 pm

Well - I am a bit of a noob and I suspect that in the end, it is me who is probably doing something dodgy.  (I reported my issues with these chips in this thread: you gave me some suggestions on how to debug it.)

I also assumed that maybe this was just a difference between the PDIP and the TQFP version.

They do offer a programming service. Quite possible they could have mixed it up.

Is there any other explanation for what I observed? No matter which programmer I used they gave back somewhat arbitrary device ideas (lots of zeros and fs. i.e. 0x0000ff or 0xffff00). As soon as I added the crystal, everything was fine.
6  Community / Bar Sport / Re: smd ZIF? on: February 03, 2014, 05:43:58 pm
Yes, that was my understanding. However, the atmegas I bought *seem* to require a 16mhz clock to be recognized.

I tried burning the bootloader to them using USBasp, MKII and Arduino as ISP but had no luck. Once I connected the crystal, everything magically worked.

Once I set the fuse so that it runs with the internal crystal, I can remove the external crystal.  I have not tested using the pins for GPIO though.  
7  Community / Bar Sport / Re: Arduino working at 3.3volts on: February 03, 2014, 05:34:27 pm

I think we should draw a distinction between product development and design-prototyping.

If you are an engineer and are developing a product, working outside of the specs is problematic for a number of reasons. (I won't enumerate, I think it has been discussed enough.)

However, I am not an engineer, I am a designer. Nobody expects me to develop products, rather I am expected to com up with interesting concepts. I am expected to be able to communicate these. In order to do so, I build prototypes. I do not invest a lot of time in them, I try to get them to work by any means possible which will save me time and effort. My prototypes don't last long. They are usually dead after a couple of weeks. But thats ok. The only reason they exist is to test a concept.

It makes no sense for me to go and engineer them to perfection, because, no matter what I do - it will get rebuilt by an engineer anyway. Also, I may go through a staggering amount of iterations before something turns out the way it should be. So anything which saves me time and effort is welcome.

Information like that provided by recklessrog is valuable to me, because it may just help me out in a pinch.


Please note - I am not suggesting that we should go ahead and say 'yes this is safe to do'. I am also completely clear that it is a horrible idea from an engineering perspective. However, in order to through together a quick and dirty prototype it might just be a really useful tool.
8  Community / Bar Sport / Re: smd ZIF? on: February 03, 2014, 05:20:21 pm
hm. That would work, but I still need the XTAL pins broken out.

I just through this together. The 'paper pcb' does not line up correctly yet. Will be etched from flex-circuit material. Plan on attaching female headers pointing upwards. Gonna wait until I have more things I need etched before I try this though.

Anyone want one?
9  Community / Bar Sport / Re: smd ZIF? on: February 03, 2014, 02:10:24 pm
eh. in answer to my own question:

Time to pull up tinkercad. This should be 3d printable.
10  Community / Bar Sport / smd ZIF? on: February 03, 2014, 12:47:29 pm
Hi everyone

I have been toying with creating my own tiny smd arduino platform (some of the process is documented in this thread:

Now I figured out that the atmega328p 32-TQFP  chips which I buy from digikey are preconfigured to expect a 16mhz crystal/resonator. In my final design I use the internal timer.

I am trying to find an easy way of burning the bootloader to them, as right now I am adding a bunch of traces to my design (like a breakout for the XTAL1 and XTAL2 pins so I can temporarily connect a timing source) which I only use for burning the bootloader and then most likely will never need again.


Long story short: Does anyone know of any zero insertion force connectors for the SMD version of the atmega328p?

If you don't know of any - is this something you might find useful? I'f it doesn't exist I might try to design a 3d printed version.


11  Using Arduino / Project Guidance / Re: Monitoring battery level with Arduino on: February 02, 2014, 09:45:32 am
@lefty: Yep, all of us are aware of that. We had however previously established that the voltage at his VCC was very noise, leading to noise readings and were discussing alternatives to the default analog read which might avoid that issue.
12  Using Arduino / Project Guidance / Re: Pi + arduino + sensors on: February 02, 2014, 09:37:41 am
I'm not an expert, but this is how I'd do it.


1) I'd use a pro mini, or similar 3.3v Arduino board.

2) I would connect directly to the GPIO, using the serial pins:

RaspberryPi ---> Arduino
RX - D1
TX - D0
(I think you will need a separate power source for the Arduino. Check max ratings and do the math)
(I confuse RX and TX sometimes. double-check this.)

3) I would set the Arduino up to wait for commands (Basically treat it as a slave).  If the software on your raspberry pi needs a new value, it sends out a message through the serial port to the Arduino, and the Arduino responds by sending back the requested value.


EDIT: Yep - Grumpy Mike *is* the expert. My post was not intended to suggest that his solution is not easy/fast/smart/good. Just offering up a method I find more interesting.
13  Using Arduino / Project Guidance / Re: Monitoring battery level with Arduino on: February 02, 2014, 09:28:34 am

(@Lefty - unless he uses internal AREF)


No, if you are averaging it you might as well use the full voltage range.

You don't *need* a resistor between the battery and A2. However, I would put one there, because it would make me feel more comfortable (if you were to connect things in the wrong order, or if you changed the function of A2 to digital output you may damage your board.)

I don't think a capacitor would do much, as the input from your battery should be steady anyway.  The reason your readings are unstable, is because it is comparing the 'stable' battery readings to the 'unstable' 5v source you have. Try it and let us know :-)
14  Development / Other Software Development / Re: No drop down menu scrolling in the IDE on: February 02, 2014, 08:27:10 am
not solely an arduino problem. processing has the same issue
15  Using Arduino / Project Guidance / Re: Monitoring battery level with Arduino on: February 02, 2014, 08:08:47 am
your schematic appears correct to me.

you can use the following function to 'hook something up' to the AREF pin:

you would do that, because the internal reference voltage is constant, while the output of the minty boost apparently is not.

I think the page I linked you to should explain that.

Vin/5v connects to the VCC pin on the Atmega chip.


Honestly, if averaging over a couple of readings is enough precision for you, you should probably just go with that.


sorry for causing confusion. I should just get my own thread :-D
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