The rest of the world needs to see a unified front and to air your dirty laundry like this in an attempt to pre-empt the lawsuit is only going to turn off the recipients of this letter from the arduino brand and will cause them to look for alternatives elsewhere (of which there are quite a few by now).
What a pity, the arduino brand had a ton of goodwill attached.
For me the issue isn't the brand dying out, its decentralized uniformity. If the main organization spins into oblivion (when talented people give up because of this turmoil) who will make sure the unified IDE keeps with the times?
"Open Source is the environment we want for millions"
In my view, their actions don't seem to embody the spirit of the open source movement.
I've gotten into the arduino environment recently and really enjoy it, even though I come from an embedded background. I hope this doesn't stop the arduino environment and ecosystem.
So, what alternatives are there? I need a simple, very cheap and very lower power chip that I can program easily using a regular PC and that can interface with a few optocouplers. Would it make sense to go directly for an ATmega? Or would I need additional circuitry to make that work? If I can program in C that would be OK, I don't need the software to be 'easy to use' - the hardware I'm unfamiliar with though so that needs to be plug and play.
1. An ATmega ATTiny85 microcontroller
2. A socket for that processor
3. A coin cell battery
4. A holder for the battery
5. A resistor
6. An LED
and some wire and solder.
What going with an actual Arduino or Arduino compatible gets you, from a hardware point of view, is a bunch of ready made attachments. For instance, suppose you have some sensor that needs an odd voltage and has weird timing requirements. It will be a lot more convenient to get a shield that has that sensor, and a voltage converter, and something that deals with the weird timing and presents a simple I2C interface to your code than to have to do all that yourself.
There are some EdX courses that you might find useful.
From UTAustinX, "Embedded Systems--Shape the World" . This is a lab-based course where you do 13 or so labs using a TI Tiva Series C Launchpad. That's an 80 MHz ARM Cortex M4 board. Cost for the hardware for the course is $35-$55, depending on if you want to do a couple of the optional labs.
From UCBerkeleyX, "Electronic Interfaces: Bridging the Physical and Digital Worlds" . Another lab course
From MITx, "Circuits and Electronics" . The online version of MITs 6.002 introductory electronics course.
Was very quick to get started hacking (can program over usb from the free cloud-based IDE), and some of the boards are under $15.
Wikipedia has a list of supported MCU-families.
And the Arduino can be programmed in C; in fact, the "Arduino language" is just C (or C++ nowadays?) with some preprocessing and a bunch of helper libraries.
I've also extensively used PIC24's and they're great (fast, cheap, feature-rich 16bit microcontrollers) but I don't know of any existing boards using them (I made my own) and there isn't nearly as much documentation/sample code/libraries as there is for Arduino and clones.
But everyone was friends, right?
That's why you need lawyers and contracts and agreements about who owns what intellectual property. That's why you try to remove any and all ambiguity you can think of. Don't worry, that won't get remove all the "fun". There will be plenty of new ambiguities to squabble over that you haven't thought of yet.