Great! Everything I purchased arrived this morning. As soon as I finished my daytime work, I started wiring it on my breadboard. Here is how it went:

OLED display

OLED display worked like a charm on Arduino UNO. I had some minor issues with Spark Core, probably due to my misunderstanding of the cloud based IDE. Anyway after working out the issues, I managed to run Adafruit's OLED examples.

Thermal Printer

The thermal printer is a totally different story. Nothing worked on Arduino. Nothing could have worked on Spark, as no one ported the library yet!

I first tried Adafruit's library. It printed only some dots instead of lines. After a quick google search, it turned out Sparkfun is providing similar printer, so obviously I had to try their examples. This didn't end well. The code was incompatible with my version of Arduino IDE. I wasted an hour or so trying to fix it and still didn't manage to get proper results.

I started to suspect my printer is broken, as even the build-in printer test was failing. It kept printing "CP437" text in a loop. This made me think of a similar problem I had with under powered audio amplifier in my last project (Back To The Future clock). It turned out my 2A 5V power supply connected through a mess of cables was at fault! Because of the lack of power, the printer kept resetting every time it printed something (a line of text or part of line of text).

Once I solved the power issues, Adafruit's Arduino code started to work. Then I ported it to Spark Core (I'll publish the code soon). Now I have a working example running on Spark Core, first the entire print test, then the OLED test.

Spark Core

I managed to run Spark Core and generally I'm happy about it. I feel however very limited by the amount of RAM it has - 20KB SRAM. Seems a lot compared to Arduino UNO, but considering hackaday.com home page has almost 100KB and it's news feed is 40KB, I have to reconsider my plans. Sure one could extract all the information from a stream, but this has limitations too, mostly a lot more code and more it is difficult to test and debug.

Additionally I was suggested today to include prints of weather forecasting including graphical representation of weather. All this requires additional RAM. I'm thinking right now I could add some more powerful board for main logic and use Spark Core as WiFi module and probably interface for the OLED and RGB leds. I have 3 linux boards that could work: Raspberry PI model B, ODroid U3 and Olimex iMX233 OlinuXino Micro. For now the best candidate for the task is the OlinuXino, as it's small, low power device with 64MB RAM. It's only problem is it lacks additional UART (there is one used for terminal) or I2C - at least it looks that way), so I don't know how would it communicate with Spark.

What next?

It's a shame I joined the competition that late, but I'll try to make the best of the time I have left.  Tomorrow I'll make a decision on how to proceed with the problem of RAM and I will prepare the demonstration video.

Whish me luck!