My 2µF » PCB

RGB LED Toy — It works

robert — Wed, 09 Dec 2009 15:41:20 +0000

Well… sort of.

I finally got the PCBs from sparkfun! Almost 6 weeks, 9 days only for the “air mail” letter to get to me. Maybe my “dear friends” at the customs office were “busy” again.

Unfortunately my request to change the design I had ordered with an updated one seems to have gone unheard. Even though I sent them an email only a few hours (at most) and the design had not been panelized at that time. Oh well. On the bright side: I got 4 boards and payed for 2 ;-)

The negative effect of the “not so up-to-date” PCB is that auto-reset doesn’t work. So far I didn’t have any problems getting code onto the board using the Lilypad bootloader. Also the LED order is a bit confused, but that can be fixed in software using a simple array pin mapping.

Here’s a short video:

www.youtube.com/watch?v=PtLpr-RSAT8

And the Arduino code (ATmega168/328):

For code and design files click on ‘Projects-->GIT repo’ in the menu above.

Notable annoyances:

- These LEDS die like flies. Touch’em twice with the iron and they’re dead as a doornail.
- They also seem to suck in the flux and short out.
- I’m down to just one working board, as I’ve killed 5 LEDs today.

And the last video for today:

www.youtube.com/watch?v=XucMpC-QNHQ

Once I get the “replacement” RGB LEDs into my fingers I’ll fix the 2nd board and see how it looks on my BIKE! It should make a perfect taillight. Perfectly illegal in this country too. Muahahaha. I’ll have to find a good use for the other 2 boards too ;-)

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RGB LED Toy — first order at BatchPCB

robert — Sun, 01 Nov 2009 04:05:40 +0000

For quite some time I have 19 SMD RGB LEDs sitting in one of my electronics boxes. It used to be 20, but I’ve ruined one while trying to solder it to perfboard. They are 3 single LEDs put into one package, no common anything. The board contains an ATmega168 chip, a few resistors, capacitors and headers and of course 8 RGB LEDs. I designed the board a few months ago, but never managed to have it made. It’s a good way of testing BatchPCB. The boards themselves are manufactured by Gold Phoenix. I’ve done business with them directly before, so I know the quality will be high – unless something goes wrong during the panelization.

For code and design files click on ‘Projects –> GIT repo’ in the menu above.

I’ve already discovered the first error. The LEDs are activated by PORTB. Unfortunately the pins are not ordered sequentially. Oh well, can’t get everything right the first time. At least it can be fixed with some code ;-)

All fixed.

→ Update 1: 01.12.2009:

BatchPCB have finally shipped the boards to me. Mine were on panel 553, while panle 580 had already been shipped back from GoldPhoenix. Either it was forgotten, lost or the panels get shipped back to them in random order. Now the only question that remains if whether they put my flawed design on the panel or the one I submitted a few minutes later. Of course I had sent them an email to let them know about that. Let’s find out if they read customer emails. If I’m lucky the boards arrive before xmas. Maybe the customs guys spare me with their curse this time. Waiting for more than 4 weeks is bad enough.

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V3.04 PCBs from MakePCB have arrived

robert — Fri, 17 Jul 2009 20:32:49 +0000

I’ve waited for 5 weeks for the 2nd batch of the 64-pixel RGB matrix controller boards. This time I ordered from MakePCB as I wanted to test another PCB manufacturer. Also I couldn’t get gold plated pads from GoldPhoenix for a reasonable price. As far as I can see right now, the boards are of good quality and the price was very attractive (including gold plating). The new boards are just 1mm thick and come with blue solder mask and are translucent when held against a lamp. The silkscreen has been updated and now lists Arduino like pin functions of the PORTC/D headers.

I couldn’t resist and assembled one board today, it’s Friday night anyway. No problems, solder mask didn’t melt, no shorts.

Front side:

Back side:

Fully assembled + matrix:

I really like spending my time with this sort of stuff, extreme satisfaction. Soldering is fun and it even looks beautiful. I’d buy from MakePCB again, but if I wanted some PCB really quick I’d choose GoldPhoenix again. They ship with FedEx and my last order with them just took about a week until delivery. Also communication with MakePCB is a bit weird at first. You get an account on their website, choose what you want, upload your design and that’s it. You get one email to confirm the order including payment request and that’s it. I wasn’t sure if there were any problems or whatever. Also their website doesn’t list any status information (which would be VERY nice to have). Still, they deliver good boards at a very attractive price.

As per request, here’s a little comparison between this device and SeeedStudio’s RainbowDuino:

First the similarities:

Both units can talk serial and I²C, the pin mapping for the LED matrix is the same for both boards, the LED matrix sold at seeedstudio works for both of them.

Now the differences:

RainbowDuino uses high power constant current LED drivers and doesn’t need current limiting resistors. The maximum current can be adjusted with a single POT for each color. That way you can easily adapt for different LED types to get a nice white. It’s a professional LED driver. The PCB allows for easy daisy chaining to build larger arrays. The RainbowDuino also comes with a voltage regulator. The downside of this is that those chips are impossible to get in small quantities, I’ve tried but to no avail. I didn’t find them at digikey/mouser/farnell. My device just used plain 74HC595 shift registers, so the LEDs will never be as bright. But those chips are dead cheap and if you fry them, you can get them virtually everywhere ;-)

By design choice the R. used direct port manipulation to address the row driver. This costs 8 GPIO pins. Therefore the R. can only provide 2 ADC/GPIO pins. My controller on the other hand includes a general purpose switch, reset switch, 8 free ADC lines (6 can be used as digital GPIO too), 8 GPIO lines (1 used for onboard LED, 3 offer PWM). It’s also designed to accept shields stacked on it’s back side.

Another way of looking at it is this:

If you want a super bright LED display you’d take the RainbowDuino, but you will most likely need an additional *duino in your project to do all the interfacing with the PC/switches/potentiometers and so on. If you can live with a normal brightness display and need to talk to lots of buttons and read analog values my board will work as a standalone and doesn’t need a 2nd *duino to work. Just get a BUB/FTDI cable and you’re good to go. You can even use perfboard to build shields for it on it’s back side, maybe add a battery pack or RTC chip.

And finally, an important difference:

SeeedStudio is a company and I’m a hobbyist.

This project made with the intention “from user for user” in mind. If you understand the ShiftOut() tutorial on the Arduino Playground and ignore the interrupt driven part, which is a bit tricky at first glance, you can easily understand how it works. It’s basically just a breadboard circuit put on a nice (and good looking) printed circuit board and some demo code to get started. Not a terribly polished product, it requires user input to “shine” ;-)

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