Hardware Reference
In-Depth Information
MAC Address
MAC addresses, unlike IP addresses, are globally unique. (Well, they are sup-
posed to be, but in practice they often are not.) MAC addresses are assigned to
every physical network interface and do not change. For instance, when you
buy a computer, the Wi-Fi module inside has a unique MAC address, and the
Ethernet adapter has a unique MAC address. This makes MAC addresses useful
for identifying physical systems on a network.
HTML
HTML, or Hypertext Markup Language, is the language of the web. To display
a web page from your Arduino, you will write some simple HTML that creates
buttons and sliders for sending data.
HTTP
HTTP, or Hypertext Transfer Protocol, defines the protocol for communicating
across the World Wide Web, and is most commonly used in browsers. HTTP
defines a set of header information that must be sent as part of a message across
the web. This header defines how a web page will display in addition to whether
the request was successfully received and acknowledged.
GET/POST
GET and POST define two ways for transferring information to a remote web
server. If you've ever seen a URL that looks like
www.jeremyblum.com/?s=arduino
,
you've seen a GET request. GET defines a series of variables following a ques-
tion mark in the URL. In this case, the variable
s
is being set to
Arduino
. When
the page receives this URL, it identifies this variable, performs the search, and
returns the results page.
A POST is very similar, but the information is not transmitted in a visible
medium through the URL. Instead, the same variables are transmitted transpar-
ently in the background. This is generally used to hide sensitive information
or to ensure that a page cannot be linked to if it contains unique information.
DHCP
DHCP, or Dynamic Host Configuration Protocol, makes connecting devices to
your local network a breeze. Odds are that whenever you've connected to a Wi-Fi
(or wired) network you haven't had to manually set an IP address at which the
router can connect to you. So, how does the router know to route packets to you?
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