Great starting point to get in the ARM micro controllers
For ARMinARM for Raspberry Pi A+/B+/Pi2
I have been looking at playing with ARM micro controllers for a while. Jeelabs.com was the catalyst for me, this blog page : http://jeelabs.org/2015/11/25/pi-based-stm32f103-development/index.html eases you into what can be done with the board. The easiest is to start with Espruino.
Espruino is a Javascript interpreter allowing you to write code for the micro in Javascript. It has a huge array of examples. Programming the board is through the a Serial Port. Espruino also comes with an easy Chrome app or online IDE.
Next up is MapleMini. MM is an Arduino compatible setup that allows you to code via the Arduino IDE. This gets you into C/C++ code.
Then things get serious with CMSIS. Cortex-Microcontroller Software Interface Standard is what professional embedded developers use. It allows then to write code that can be reused on similar processors. It is also what the ARM foundation suggest.
Adding a Raspberry Pi to the party is very,very helpful. It makes the development environment very clean and isolated. The setup code is very easy to work with but it does require that you know a bit about running a Raspberry Pi.
I am very happy with this product, I highly recommend it and support is also top notch.
Keep up the great work!!!