Hmm.. but then what is the point of __low_power_mode_off_on_exit() ? This goes counter to what I've read in https://www.amazon.com/MSP430-Microcontroller-Basics-John-Davies/dp/0750682760
(I'm trying it, and if it works, great, but I'm still confused :-/).
EDIT: Didn't work. The SR is pushed onto the stack when waking to service an interrupt then popped back--according to that book, anyway. so the device should go back to whatever mode it was in prior to servicing the interrupt. It seems like LPM0 isn't enabling interrupts. I'll try directly running the intrinsic to set the SR.
This is far and away your best introduction to the msp430:
http://www.amazon.com/MSP430-Microcontroller-Basics-John-Davies/dp/0750682760
TI's datasheets are quite good, and you will be able to understand them easily after reading the Davies book.
TI also provides example code in both C and assembly to demonstrate the basic using of just about every peripheral on every part. Those make for a great rosetta stone.
I am in your place. As others have said, get a dev board and just start doing something. I bought a MSP430 and am going through the MSP430 book by Davies, so far so good!
Seconding what other users have posted here, the datasheet is your best friend. But I might also recommend for a beginner MSP430 Microcontroller Basics by John H. Davies. I also started with the Arduino as well and when I did my internship at TI, this is the book my mentor recommended to me. The author does a really good job of going in-depth into every feature of the MSP430 and explains not just what the feature is but what it could be used for. He also provides workable Assembly and C examples. And the book isn't just good for the MSP430, you'll learn about topics that useful across the spectrum of embedded systems.
If you can get a copy of this book, I'd give it a try. http://www.amazon.com/MSP430-Microcontroller-Basics-John-Davies/dp/0750682760/ref=sr_1_1?ie=UTF8&qid=1321841399&sr=8-1
It really goes step by step from the very basics and explains how a MCU work. It described how TI's MSP430 works, but it's applicable to any MCU.
It's daunting at first, but in reality it's really not that complicated.
Usually GOOD books are much better than other teaching resources.
Here's a book on the MSP430, it seems good.
http://www.amazon.com/MSP430-Microcontroller-Basics-John-Davies/dp/0750682760
My suggestion for learning the MSP430 is as follows:
Purchase the Davies book. It is by far the easiest introduction to the MSP430, and if you have never worked with a microcontroller before, it will save you a huge number of headaches.
http://www.amazon.com/MSP430-Microcontroller-Basics-John-Davies/dp/0750682760
From there, you want to download the family data sheet for the chips used in the MSP430 launchpad:
http://www.ti.com/lit/ug/slau144i/slau144i.pdf
And the sample code:
http://www.ti.com/lit/zip/slac485
You will notice that for each peripheral on the chip described in the datasheet there are a number of examples which show how it is used, in both C and assembly. Work through each chapter in the family guide along with the sample code. When you understand the sample code you will have a very good idea of how the chip works, but be aware that the sample code only demonstrates a small fraction of the capabilities of each peripheral. That is to say, there is much more information in the data sheet than is demonstrated in the sample code.