TkInter GUIs can get extremely long very quick. Fortunately they can be split into multiple files - especially if you give them a class wrapper. The important thing is that you pass the relavent parent elements so more widgets can be inserted into the frame or window.
The below example shows how to take the previous python GUI example and break it into multiple files using Python modules.
Node.js is JavaScript that can be run outside of a browser. It is often used to make a fast server for dynamic content.
Probably one of the biggest advantages to Node.js, aside from being one of the fastest and easiest to learn server environments, is that JavaScript is the lanugage used on browsers, allowing you to program both the server and client in the same language.
Balancing an inverted pendulum is the typical example when demonstrating a control system. A weight on an arm above the rotation pivot is an unstable system. It has one stable point when the weight is perfectly balanced. If the weight is slightly on either side of this point it will begin to move away from this stable point. On the other hand, a weight on an arm below the rotation pivot is a stable system. The weight is stable at the point exaclty below the pivot as well, but if it is moved slightly away from this point it will move back towards it.
I have built a simulation using web standards like JavaScript and HTML so you can observe the impact different PID controls have on an inverted pendulum. You can modify the gains of the proportional, integral, and derivative controls to test how each component works. The simulation is optimized to be used with Chrome and Firefox, but has a limited set of features available for Internet Explorer.
A screenshot of the simulation. Click to do your own simulations.
The Udoo is relatively pricey, but has some great features and is relatively well documented. They bill themselves as a "Raspberry Pi + Arduino", but that is selling themselves a little short. Anyone could plug an Arduino into the USB port of a Raspberry Pi. The ARM processor is faster and more capable than the Raspberry Pi, but also has the same pinout as the Arduino Due with the exception of a few missing pins like the analog ones. Additionally, there is an Arduino Due-like processor that has full access to the same pins. That's right. Both processors can access the same pins. They can access different ones at the same time, or even send signals to each other if you configure it that way.
It features an ARMv7 processor, not ARMv6 like the Raspberry Pi. The newer instruction set means each core of the ARM processor is significantly (2x) faster at many tasks. More importantly, it is the same instruction set supported by popular Linux distrobutions like Ubuntu and Android. The Raspberry Pi's ARMv6 processor is pretty much restricted to the Raspbian Debian derivative.
Each test was run on an Udoo with a Quad core while X.org was running and a Chromium window was open. The additional load, for the most part, is not important because most these benchamarks only test one of the cores of the udoo at a time. Only the 7zip test ran accross all cores.
To compare the benchmarks to those of the Raspberry Pi (wiki), I used this package (zip). Also compare to my Angstrom BeagleBone Black test .
The Adafruit Ultimate GPS Breakout board is an excellent way to get started with GPS and Arduino. Adafruit does an excellent job providing tutorials and code for the user. I would suggest checking out their provided tutorials and code before looking elsewhere.
When I was working with the GPS, I made a few changes to the code that Adafruit provided based on how the Arduino handles floats (or doesn't handle them). The changes that I made are not particularly necessary depending on what it is being used for, but does increase the accuracy of the module on the code level. However, I suggest that you become familiar with how the unit works first before attempting to alter the code.
The MCP23017 and MCP23008 integrated circuits are a great way to add more I/O pins to a microcontroller. They use the i2c standard, so they can share the same serial line with 254 other sensors and even up to 8 other chips of the same exact type. They are particularly good for a Raspberry Pi because they have higher current capabilities than the Raspberry Pi's GPIO pins. The MCP can supply 25mA per pin and the Raspberry Pi can only do less than 16mA per pin. 20mA is enough to fully power a strong LED, so 16mA may not be enough in some cases.
