Stefano Tommesani

At the time of writing, the SkyDrive client application on Windows does not support bandwidth throttling on uploads, so if you start uploading a large number of files, it will try to use all the available bandwidth, and this behaviour has an impact on other applications accessing the Internet.

A quick fix to this behaviour is:

• install a network traffic manager app, such as SeriousBit NetBalancer (I will use NetBalancer in this example)
• start SkyDrive app
• start NetBalancer, and look for the SkyDrive process (SkyDrive.exe), right-click to open the menu, and choose Upload Priority | Limit...

FizzBuzz is described as:

Write a program that prints the integers from 1 to 100. But for multiples of three print "Fizz" instead of the number and for the multiples of five print "Buzz". For numbers which are multiples of both three and five print "FizzBuzz"

It takes a couple of minutes to write a few lines of C++ code that satisfy the requirements:

#include <iostream>
 
using namespace std;
int main () {
 
 int i;
 for (i = 0; i <= 100; i++) {
 if ((i % 15) == 0)
 cout << "FizzBuzz" << endl;
 else if ((i % 3) == 0)
 cout << "Fizz" << endl;
 else if ((i % 5) == 0)
 cout << "Buzz" << endl;
 else
 cout << i << endl;
 }
 return 0;
} 

But then the examiner may ask you to add some more checks, such as printing a different string when the number is a multiple of 11 or any other number, and the code quickly becomes ugly. In fact, the major mistake that you can make with FizzBuzz is using the wrong sequence of checks, for example checking for modulus of 3 before that of 15, so that FizzBuzz is never printed; this is obvious with only 3 simple checks, but gets more complicated with a longer list of more complicated checks.

So why not spend a few minutes more than those required to write a trivial solution, and propose a fully object-oriented solution that is designed for extensibility?

The Flash library by Mikal Hart is a wonderful piece of software for improving simple web server apps built on the Arduino: the main problem when designing such apps is that the limited number of RAM available forces the designer either to use an SD card to store the files that are part of the web site, and/or store some HTML fragments in the PROGMEM area, and copy them back to normal RAM to modify and include them in the server HTML packets. The Flash library greatly simplifies the second technique, as the following code fragment highlights:

FLASH_STRING(WebPageHeader, "HTML source code");
Client& client = web_server.get_client();
WebPageHeader.print(client);
 

The FLASH_STRING macro declares a string contained in PROGMEM, so that it does not decrease the available RAM. Streaming that string is as easy as calling the print method and passing the Client connection of the web server as the parameter. Using this technique, dynamic generation of web pages includes both static parts stored in PROGMEM as FLASH_STRINGs (for example, page headers and footers, top menus, etc.) and dynamic parts that are generated by code (for example, tables containing data values coming from attached devices).

Here is video footage from a real-life scene: it's a windy day, so the camera is slightly shaking, and there is a lot of action happening in the road below. This video sequence is useful for the following tests:

• - checking the direction of moving vehicles (there are bikes moving in the wrong direction)
• - classifying moving objects (cars, buses, motorcycles, bikes etc.)
• - rejecting false alarms due to unrelevant movements (the shadow of the trees is costantly moving, but it should not trigger an alarm, while people walking and running should)

You can download this video sequence (running time: 9m 42s) from Dropbox clicking on this link. (if clicking on the link starts a video player, right-click on the link and choose Save Link As.. from the popup menu)