Is arduino the best?

[c4757p]

That is one nice looking homemade board. I like the right-angle plug, too 

[TerminalJack505]

That is one nice looking homemade board. I like the right-angle plug, too 

Thanks! 

The "solder resist" is pretty much just cosmetic but adds a nice touch, I think.  It will peel off if you drag a hot soldering iron across a trace.  It's pretty durable, otherwise since it is actually designed as dishwasher-proof glass paint.

[c4757p]

I've used glass paint for the same purpose. I've found it's better than cosmetic - by using toner transfer with the solder mask plot, underneath the paint, then clearing it out by dissolving the toner with acetone, I can get pretty good resolution for a useful solder mask. I just bake the paint a second time to undo the roughening that the acetone causes. It isn't extremely heat tolerant, but it still helps quite a bit with SMD parts.

What specific kind do you use? I love the traditional green, but all the green ones I've tried are so dark that they obscure the underlying traces (and if I thin it, it doesn't stick).

[TerminalJack505]

Well, that's a good question.  I'm pretty sure I used the paint seen at the far left in the attached photo.  It was either that or the paint in the middle.  I did a test of one and found that it was too opaque so switched to the other. 

I've had good luck with the Pebeo Vitrea 160 as well.  It doesn't have a very long shelf life, though.  It will get really thick just sitting in the bottle.

I use a silkscreen to apply the paint and mask out the pads and vias.  As-is, the paint is too thin for silkscreening so I thicken it a little with cornstarch.  This method (the silkscreen) leaves air bubbles in the paint, unfortunately.  These could probably be removed by popping the board in a pressure/vacuum chamber.

I'll have to try your method.  I wouldn't have thought acetone would be able to get to the toner to dissolve it once the paint was applied.

[c4757p]

I've had good luck with the Pebeo Vitrea 160 as well.  It doesn't have a very long shelf life, though.  It will get really thick just sitting in the bottle.

This is what I usually use, though you're obviously using a different shade than I have. The store near me only has one "green" available and I didn't realize there were more... I also have a bright red that comes out looking very professional, remarkably close to the "real" red solder mask - but I hate the red solder mask... I haven't noticed a shelf life problem at all though!

I'll have to try your method.  I wouldn't have thought acetone would be able to get to the toner to dissolve it once the paint was applied.

You have to let it soak for a bit, but it does a fine job of seeping through the paint. If the paint's too thick, it's still tough to remove, but if it's thinly applied it'll push right off. Of course, YMMV - it might differ with a different brand of paint, and I distinctly remember somebody on this forum saying they had toner that didn't dissolve in acetone too! (I have never seen that one - acetone seems to chew through just about anything with vigor, including toner...)

I've found that with this method, it's fine enough (if I'm not a clumsy hamfist when removing it) to unmask pads on a 32-pin QFP and still leave mask in between. I'm sure the recessed gap between the pads helps as well. You're obviously not going to be doing 0.4mm BGAs with it though 

[TerminalJack505]

This post has a picture of a board that I used the green Pebeo Vitrea 160 on.  As you can see it's pretty transparent.  I thought the yellow paint (pay no attention to the crappy board layout) looked pretty good too.

I'm like you, I don't like the completely opaque paints.  I bet the red paint you're talking about (Pepper Red?) is the same as what's seen in the attached picture.  I thought it looked pretty good.

[c4757p]

Ooh, the yellow is nice, and the green looks great too! You make some very good-looking homemade boards.

I think the red I had was brighter, but I've since thrown it out and don't remember what it was.

[kt315]

That is rather interesting... Can you go over the steps to create the solder mask once again please?

Do you use toner transfer to cover the pads on the etched board, paint it over, and when the paint is cured remove the toner by bathing the board in the aceton?

TerminalJack505, how do you protect the pads when painting the board?

[westfw]

Can you use toner transfer to create a screen-printing screen?  You'd have to use some sort of high-temperature fabric for the screen, I guess...

[TerminalJack505]

That is rather interesting... Can you go over the steps to create the solder mask once again please?

Do you use toner transfer to cover the pads on the etched board, paint it over, and when the paint is cured remove the toner by bathing the board in the aceton?

TerminalJack505, how do you protect the pads when painting the board?

I use a product called StencilPro to create a silkscreen mask.  This is a UV sensitive silkscreen.  It's a pain to get properly aligned on the board sometimes which is why I want to try c4757p's toner transfer method.

For the method I use to create the mask I just export the appropriate layer as an image from Eagle, do some minor manipulation in Gimp then print it on a transparency.  I then expose the stencil. 

When I'm ready to paint the board I clean it with alcohol, thicken the paint with some corn starch, align the stencil over the board and use a squeegee to apply the paint to the board.  The paint has to cure for a day or two.  Once it's cured you bake the board according to the instructions on the paint.

The attached picture is the mask I created for this project.  Notice how the transparency is doubled-up.  This helps keep too much UV light from getting through the toner.

BTW, in an earlier post I said that I thought that I used the Folk Art paint for this board but I'm now 99% certain that it was actually the Americana brand.

[TerminalJack505]

Can you use toner transfer to create a screen-printing screen?  You'd have to use some sort of high-temperature fabric for the screen, I guess...

I've never thought of that.  If you could it probably wouldn't be very durable but that might not be an issue for one-off projects.

[ptricks]

The best results will come from using UV cured paint.  The paint is more readily available than most think, go to a beauty supply store and you can buy it as UV cured nail polish paints. Print up your solder mask so that only the parts you want to keep are exposed to UV light, expose, then rinse off the excess paint.

[c4757p]

Do you use toner transfer to cover the pads on the etched board, paint it over, and when the paint is cured remove the toner by bathing the board in the aceton?

Precisely. You'll need something relatively gentle to scrub the paint off, though, or you could end up taking it all off. The acetone does soften the paint as well as the toner, it's just much more aggressive on the toner. I usually bake the paint a second time to smooth it out, since the scrubbing with acetone roughens it a bit.

[c4757p]

The best results will come from using UV cured paint.  The paint is more readily available than most think, go to a beauty supply store and you can buy it as UV cured nail polish paints.

  I will try this!

[kt315]

Well, thanks for the info. I've made a fare share of the boards, but I've never tried to create a solder mask. I certainly should try it.
What is the simplest option for UV light source?

[TerminalJack505]

Well, thanks for the info. I've made a fare share of the boards, but I've never tried to create a solder mask. I certainly should try it.
What is the simplest option for UV light source?

In the case of StencilPro: Sunlight.  It takes less than a minute of exposure to direct sunlight for it to work.

If that's not an option then a florescent lamp works too.

[TerminalJack505]

I just finished soldering the USB cable to the board and made an output connector cable so I thought I'd put the board its (recycled) enclosure to see how it looks and fits.  It fits great and the LEDs look like they line-up perfectly with the light pipes.

I haven't powered it up yet or programmed the MCU so I thought I'd upload these photos for posterity.  Now comes the most anxious part--powering it up.

[Anson]

That came out great! Now you need to change the logo. 

[TerminalJack505]

That came out great! Now you need to change the logo. 

LOL.  I don't know what I can do about the logo.  It also has an FCC compliance/made in Taiwan sticker on the back that I'll probably leave on as well. 

The case turned out to be pretty much just the right size for the job.  The light pipes for the LEDs were convenient as well.  There's no power LED, though.  The Link LED only lights up when the remote's voltage is sensed.

I powered it up and programmed the MCU last night and it's working like a charm.  Right now I just have a simple loopback circuit setup to test it and have more testing to do.  I need to test the flow control signals (CTS#/RTS#), for example.

I still need to design and build the programmer.  This is just the USB-to-serial device.  I don't think it will take as long for the programmer since much of the design will use what I learned during this project.  It will use the SN74LVC2T24 ICs as well for level conversion and power sequencing immunity (they basically keep either circuit from latching-up the other when one is powered-up and the other is powered-down.)

[kt315]

It does look great indeed.  Nice job. 

[TerminalJack505]

Thanks, Kt315.

Here's the beginnings of a Theory of Operation document.  It isn't complete yet but it has a section that describes the purpose of each of the components in case anyone is curious about what certain components are doing in the circuit.

The schematic it references is the same one posted here.

[c4757p]

Here's the beginnings of a Theory of Operation document.

...I think I'm in love. It's been a long time since I've seen someone bother with this kind of documentation.  (the last two are my toes)

[creepyoldenj]

Hi,

I used to be a big user of Motorola CPUs way back in the day. But when I got back into MCUs a couple of years ago
I looked at a lot of platforms and it pretty much boiled down to PIC32MX or ATMEL/AVR 8/32(so far).

1. Hardware: lots of variety and low cost.
2. Support: Least crippled tool chains from Major-corp., or cheap/ open-source alternatives.
    Huge hobby base, especially AVR/Arduino.
    Atmel and Microchip have great online resources.
    Arduino site is expressly set up to be user friendly to beginners and non-tech heads.

The trick is not to be seduced(as I was) into some wiz-bang development platform that is cheap upfront
but is a hassle on the back end; expensive, crippled, lamer tool-chains, narrow hobby base.
The fact is that virtually all cheap Major-corp. dev/demo boards are targeted at
EEs who work for a company in the hope that they buy  bizillion of their chips to put into washing machines or cars.

My only b*tch with AVR and Microchip(not exclusively) is that printed books on using these devices which go beyond
casual "Maker" needs are for the most part EE textbooks that are too expensive for me.
So I've had to spend many an hour on the web finding well written tutorials and coding examples for
MCUs that I like.  Also finding good blogs/forums on tips, tricks, and work-arounds is a big plus.

The most important advice is that practically all MCUs are coded in ANSI C or C++, or  C-whatever.
The better you get at C in general, the easier your life will be at coding for almost any MCU.
Later on, assembly code is good to know on your favorite MCU, because at some point
your gonna want to or have to tweak your C source using assembly for
for those routines that go outside the scope of your C compiler libraries.

I like ANSI C and the Pellas C IDE works well for me for generic C hacking and it's free.

If you want a cheap thrill farting around with controlling in BASIC try the
Duinomite/ Maximite boards or the Coridiumcorp.com BASIC chip.

Coridiumcorp claims that their $10usd chip(NXP LPC1114-28 pin dip) will run the equivalent
of 10 million lines of BASIC code a second. They give you the IDE-compiler for free.
Not a bad deal if true!

If your are a noob go with Arduino first.
Be careful when buying Arduino hardware online.
Buy from authorized sellers of authentic Arduino parts to support Arduino.
Arduino is open source so everybody and their dog has been banging out
Arduino clones and the quality of these are all over the map.

My general rule about buying clones, knock offs or equipment
is to let others buy it first and scrutinize the reviews on the item
and the supplier's street cred.
Otherwise deal with an authorized vendor: Digikey, Mouser, Avnet, Newark, etc.
I'm really anal about this since I got burned buying some fake
MCU parts, and crap test equipment from eb** and online resellers
from distant lands. ;~)

If you eventually want to break away from 8-bit,
I would suggest MIPS core chips like the PIC32MX or if you go ARM: Atmel or NXP LPCxxxx(LPCexpresso)

Olimex also has a broad range of good quality SBCs at a good price. But read the specs and look at the
schematics carefully on the board you are interested in to make sure the board has the right
mix of devices and features you want on it.  If the board in question is flashed with
code make sure that the code has the features, compatibility, and updatability you are comfortable with.

All of the above is just my very personal, humble opinion regarding my experiences dealing with MCU chip choices
and buying electronics on a small budget.

Ciao
Happy coding

[TerminalJack505]

Here's the beginnings of a Theory of Operation document.

...I think I'm in love. It's been a long time since I've seen someone bother with this kind of documentation.  (the last two are my toes)

LOL.  Well, it is just as much for myself as it is for anyone else.  If I don't document it now I'll be scratching my head 6 months from now about some aspect of the project.

I'll try to post the firmware and Eagle project at some point.  I don't know if they'll ZIP up small enough to post or not, though.  I'm sure I'll have to whittle down the Eagle project since it's about 16MB unzipped.  I'll probably just leave all the datasheets out and get rid of all of the automatic backups then it should ZIP up fairly compact.

[Anson]

That document was very informative. I think I may start making notes on my designs as well just so when I come back to them after a few days I haven't lost everything. It is also very good for getting things to click when you are trying to understand what you are trying to do.