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.
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” ;-)