I need to put 2 Arduino's in my project which will be long term and permanent. I looked at the Pro as that and it said semi-permanent installation. What does this mean exactly? Also if it's not ok for a permanent project then which Arduino is?
Arduino Pro mini's are what you need.
Once my project is completed and in a box, etc. I consider it permanent. So far, I've used Uno's. The Arduino board is my hardware development system, microcontroller-programmer, and the processor board in my final project.
Pro Mini has not USB driver on board, that means you save on parts and power. it also means you need to make up a programmer. but that is supper simple. most units have the same pin-out so you can solder female header and just plug it in.
Personally, I use the NANO just to get the USB programmer.
Hi Jon Ivan, I really dig the Steam Punk look - it fits so well with Arduinos and the surrounding amateur electronic movement! I've built a clock or two myself in that style. Semi-Permanent generally means that connections to the Arduino (and other components) are soldered, rather than push-pin connected. Unless you are good with a solder-sucker, the connections are permanent. As opposed to breadboarded, which is how many Arduino projects are made.
I have used 'naked' avr chips (328, Tiny84 and 85s) Arduino unos (genuine, clones, and 'at-heart' modules), Arduino Micros, and Adafruit Trinkets and Pro Trinkets. There are LOTS of other modules. The key is to look for compatibility with the Arduino IDE, so you can take advantage of the HUGE amount of support and pre-written code.
Real Arduino/Genuino boards are among the best constructed ones, and guaranteed to meet the compatibility requirements.
(The Micro is my go to board, for size, convenience and the extra 512 bytes of RAM.)
I have a Sparkfun ProMicro which is cheap and has a USB connector. (I had two of them but, for some strange reason they don't take kindly to being plugged into the socket incorrectly 
)
...R
Robin2:
I have a Sparkfun ProMicro which is cheap and has a USB connector. (I had two of them but, for some strange reason they don't take kindly to being plugged into the socket incorrectly...R
I like the mini's that offer 8 ADC channels.
note sure why the sparkfun only offers 4, unless they use the others for the USB programmer ?
I used a mini in a design, needed I2C for the RTC. darn things have odd pin placements.
I would offer that if you want to use a mini of any type in a board, get them from some reputable place. genuino, sparkfun, adafruit, spend the few $$ more and know that you can get an exact pin replacement.
if you try to save a dollar on e-bay, I can assure you that the chances of your next purchase being pin or hole compatible or aligned, will be very low.