Go Down

Topic: Want to make an Arduino Mini-kinda Clone? (Read 5822 times) previous topic - next topic

Deviant

I was just curious.

The mini is "almost" the  perfect for what I want do....

However,

1. I don't need all the pin outs.
2. There are no mounting holes.
3. For the pin outs that I do need, I'd like to add a ground nearby as required.
3a.  The pins would ideally use some type of right angle friction lock connector.

So my question.

1. How many of these boards would I need to make to get a similar cost per board to the ~19 bucks for the mini.

2. Assuming that my surface mount soldering skills sucks.  Is there someone that will print and solder the boards to my specs?  At a hobby or production level.

Finally, I tried to play with Eagle, which appears to have a personal vindetta against me.

Is there another program that make the files required to send some place like batchpcb? Or that can work with eagle files?

Or is there a find a freelancer type spot for eagle gurus?  What would I be looking at one a cost for someone to modify the existing mini-arduino eagle files to something that I can send off.

Ideally, I'd like to keep the cost of the mini-like clone to under 30 bucks.  

The cheaper the better.

Thanks for any help.  I'm very knew to the circuit scene.  But I have alot of things I'd like to make.

madworm

Soldering SMD components is dead easy!

My personal exceptions are:

- 402 sized resistors. Still possible, but not much fun. And if you drop them, you'll never find them again.
- BGA/QFN as the pins are hidden under the package.

The TQFP package of the ATmega168/328 chip is really quite nice to solder. Even if you end up with many solder bridges, just use some solder wick and you're good. Just use lots of flux all the time. Ain't no magic. I recommend watching the soldering tutorials on http://curiousinventor.com

• Upload doesn't work? Do a loop-back test.
• There's absolutely NO excuse for not having an ISP!
• Your AVR needs a brain surgery? Use the online FUSE calculator.
My projects: RGB LED matrix, RGB LED ring, various ATtiny gadgets...
• Microsoft is not the answer. It is the question, and the answer is NO!

jluciani

Quote
How many of these boards would I need to make to get a similar cost per board to the ~19 bucks for the mini.


Low volume PCBs from a quality vendor are probably in the $0.50 per in^2 range.

Quote
Assuming that my surface mount soldering skills sucks.  Is there someone that will print and solder the boards to my specs?  At a hobby or production level.


This will cost you a fortune. If you can not do the SMD assembly yourself you are much better off with TH. I do the SMD assembly myself. It is not difficult for
these types of components if you make a modest investment in tools.

Quote
Finally, I tried to play with Eagle, which appears to have a personal vindetta against me. Is there another program that make the files required to send some place like batchpcb? Or that can work with eagle files?


All PCB manufacturers accept Gerber files which is an industry standard. All EDA
tools that do not have a vendor tie-in will export Gerber files. I use gEDA/PCB
which is an open source EDA tools.

I am not sure how big a mini is. I am currently prototyping some smaller through-hole kits. It may be possible to use some of my existing circuit blocks to create a new
board. See wiblocks.com for some of the physical computing tools I have done.
Some other boards that I have done with the gEDA/PCB tools are at http://tinyurl.com/6jm8tu

(* jcl *)
www: http://www.wiblocks.com
twitter: http://twitter.com/wiblocks

Deviant

I'm not opposed to attempting the soldering job.  

I'll check out the tutorial....  I have fairly steady hands, but they eyes aren't what the use to be...

I just thought if this was a somewhat reasonable option, I got offload that job.

Any suggestions on the tools needed?  Other than a big magnifying glass?

Or suggestions on a pcb supply house?  Can the supply houses provide the pads presoldered?  Or is that an extra cost that is not worth the effort?

Obviously, I've never ordered a pcb.  And there appears to be a certain level of vocab that is required.

Thanks for the help.

Deviant

Just finished watching the 101 Surface mount soldering.

They guy definately makes it look easy...

I think I might need more than the 10x eye lope though.  But if the rubbing the braid across the pins when your finish works as well as he/she shows it.  

Then maybe not.


BRuTuS

It works.

Industry standard method ;)

In fact even with the hot air tools, it is still easier IMO to resolder TQFPs back into place using the glob and suck method.

For all the PITA methods I watch other guys try to pull off, I'm usually quicker.

madworm

#6
Aug 04, 2009, 08:23 am Last Edit: Aug 04, 2009, 08:24 am by madworm Reason: 1
Desoldering can be stressful ;-)

By testing a freak idea I had after midnight (nothing good could come from that), I had to find out that 26V is no good for ATmega chips. It fried every single chip on my board... I thought I typed 2.6V on my power supply's keypad - apparently not. A good excuse to test the ChipQuik I ordered to replace an ATmega64 chip somewhere else. This stuff is just great. The paste flux has a totally weird smell and is possibly lethal, but the stuff works.

Anyhow, soldering TQFP chips shouldn't make you afraid at all. Removing dead ones requires the right method.

• Upload doesn't work? Do a loop-back test.
• There's absolutely NO excuse for not having an ISP!
• Your AVR needs a brain surgery? Use the online FUSE calculator.
My projects: RGB LED matrix, RGB LED ring, various ATtiny gadgets...
• Microsoft is not the answer. It is the question, and the answer is NO!

whosawhatsis

I recently assembled my first all-SMD board, and was surprised how easy the TQFP was to solder.

The 603 components gave me more trouble. The method I finally figured out was to apply flux, add a small blob of solder to one pad only, place the part with tweezers and then either press it down with my finger or grip it between the tweezers and the soldering tip while reflowing the blob, then solder the other side once it was aligned properly. For your first SMD job, I would recommend using an 805 package or larger for caps, resistors and leds.

I also wouldn't try it with a firestarter, get a temperature controlled iron if you don't have one. It seemed like a waste of money when I first started, but when I finally got one it made a HUGE difference.

As for loupes, the focal length is too short to use them while you're working (no force on Earth could get me to intentionally put the tip of a hot soldering iron that close to my eye), I just use it to check my work after the fact. If you need magnification while you work, I'd try one of those desk lamp magnifier things.

jluciani

My tools and supplies list is at ---
http://www.luciani.org/getting-it-done/getting-it-done-index.html

If you design your own boards and use passive parts that are 0805 or larger
and lead pitches of 0.5mm or larger you should not have a problem. 0805's
are easy but 0603's are not difficult.

When doing your design use footprints designed for hand assembly.

(* jcl *)
www: http://www.wiblocks.com
twitter: http://twitter.com/wiblocks

Deviant

If I use the exact same design/parts of the mini.  It looks like there is 15 surface components.

I believe that I could solder the 328p fairly easily given a soldering iron with a small enough tip and if everything on the video works out in real life.

I couldn't use my current firestarter.  *grins*

So I would need to get something else.  Suggestions?

I can see the smaller components being a pain.

As for the diminsions of the board.   My calipers say that it's roughy .7" x 1.3"

.48" or so would be as small as I could make it's width.  Then I expect that it would be a little longer.  1.5'ish.  

I would like to have it fit it onto .5" x 1.5" board.   But it's a little bigger, it won't hurt.   Primarily, it's the pin out locations and lack of mounting that hurts my current use.  I could even kill off the mount holes, if I had the pins in the power location.  I could make a little mounting box with slots for it to slide into.

Also, for design purposes...I don't know that I need the onboard reset switch, since I should be able to just cut the power.  Or could make it 12 pins out... and use a remote switch.

Assuming that I leave all the components the same as the current mini.  I see myself using the following pins:   4x Ground, 2x input, 2, output, 1x positive battery lead. 1x negative battery lead.

Then I would need the pins required to program it with the usb/serial.

So I'm thinking the Arduino mini with the two long row of pins remove.

Two mounting holes, 6 pins on one end for ICP, 12 on the other via a double row.

Thanks for any help.

whosawhatsis

I use a WES51, and would highly recommend it. It's probably about the least expensive temperature-controlled iron you can find, at least without going for some shoddy no-brand. I find that the slightly rounded tip that it comes with is best for packages like TQFP and SSOP, but I use the ETM tip for most other surface-mound parts. ETM is also great for use with a desoldering braid to remove solder from through-holes that are accidentally filled, which is I find really difficult with a larger tip.

.5" will probably be a problem unless you intend to put all of the power and I/O pins on one side of the board. My newest board is .5" wide, and you can see that there's not a lot of space beside the TQFP. Remember, you need space for traces to break-out the pins. If you want an FTDI header for programming, you need a row of 6 pins for that, although if you really want to save space, you can probably repurpose 2 of those as ground pins and 2 as I/O.


BRuTuS

Another good iron is the Hakko 936

Both the above mentioned Weller and this one are industry standard units.

I'm biased, but I like the tips on the Hakko units better, but that's highly subjective as well.  I've had my Hakko for over 10 years now, and have only ever needed tips.

Deviant

Thanks for the iron links.

I'll check those out.

The board that you linked the picture to.  Is more or less the size that I'm looking to do.  Long and skinny, but I don't want any pins on the sides.

As above, I'm looking at 12 pins at one end(5ground, 5digital, 2 for 9v battery) and 6 pins at the other for the ICP.  The more compact the better.  I would like to seperate the 12 pins in to 6 pairs of pins.  

Or this could be a ribbon cable that is cut to various lengths to reach the intended locations.

I really don't see myself reprogramming, but it would be nice to have the option.  I just don't want to devote alot of board space to something that I will rarely use. Although, I know that if I have option. I'll be using it more than I plan.

I don't have a .5" width constraint. It could actually be bigger, but I like the idea of have as compact as feasible.  I'd prefer it be roughly .5" wide and 1-1.75"'ish in length.

The largest that it could possibly be, would be about 1x2.5"

Deviant

I've been looking around and soldering irons.

It would appear that I have alot more tip options with the Hakko 936.

However, I'm curious to know if there are any models that I want to stay away from.  As there seems to be several different Hakko 936 sub types.

Thanks.

I'm going to trying my hand again at playing with the pcb design.


jluciani

I'm assuming that those numbers mean something to someone, but unfortunately. It is not me.  I'm guessing they have something to do with the package size of the components.

I was curious if the program that you suggested was able to make use of eagle part files.  I haven't downloaded it yet, but plan to in a few minutes.

Thanks all,

BRuTuS

You're going to have post a link to some of these 936 variants.

If you go with that one, get the one that matches this one:
http://www.hvwtech.com/products_view.asp?ProductID=209

Go Up