Arduino uno User Manual

It emits an infrared command specified by a protocol type ( protocol ), the length
of the code measured in bits ( bits ), and the code value to be sent ( value ).
Depending on the name of the protocol, the method delegates all the real work
to our IRsend instance.
handle_command implements one of the most difficult aspects of our InfraredProxy —it
parses the URL addressed by the HTTP request:
RemoteControl/InfraredProxy/infrared_proxy.cpp
bool InfraredProxy::handle_command(char* line) {
Line 1
strsep(&line, " ");
-
char* path = strsep(&line, " ");
-
-
char* args[3];
5
for (char** ap = args; (*ap = strsep(&path, "/")) != NULL;)
-
if (**ap != '\0')
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if (++ap >= &args[3])
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break;
-
const int bits = atoi(args[1]);
10
const long value = strtoul(args[2], NULL, 16);
-
return send_ir_data(args[0], bits, value);
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}
-
To understand what this method does, you have to understand how HTTP
requests work. If you wander up to your web browser’s address bar and enter
a URL like http://192.168.2.42/SAMSUNG/32/E0E040BF , your browser will send an HTTP
request that looks like this:
GET /SAMSUNG/32/E0E040BF HTTP/1.1
host: 192.168.2.42
The first line is a GET request, and handle_command expects a string containing
such a request. It extracts all the information encoded in the given path
( /SAMSUNG/32/E0E040BF ) and uses it to emit an infrared signal. Parsing the
information is tricky, but using C’s strsep function, it’s not too difficult. strsep
separates strings delimited by certain characters. It expects a string containing
several separated strings and a string containing all delimiters. To get the
separated strings, you have to call strsep repeatedly until it returns NULL.
That is, whenever you invoke strsep , it returns the next string or NULL.
We use strsep in two different contexts. In the first case, we extract the path
from the GET command: we strip off the string “GET” and the string “HTTP/1.1.”
Both are separated from the path by a blank character. In line 2, we call strsep
to remove the “GET” at the beginning of the string. We don’t even store the
function’s return value, because we know it’s “GET” anyway.
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Arduino uno Specifications

General

Form factor	Arduino
Certification	RoHS, FC, CE
Processor model	-
Processor frequency	- MHz
Microcontroller model	ATmega328
Microcontroller frequency	16 MHz
DC input voltage	7-12 V
Operating voltage	5 V
DC current per I/O pin	40 mA
Flash memory	0.032 MB
Maximum internal memory	- GB
SRAM (Static Random Access Memory)	2 KB
EEPROM (Electrically Erasable Programmable Read-Only Memory)	1 KB
Wi-Fi	No
Number of analog I/O pins	6
Number of digital I/O pins	14

Weight and Dimensions

Board dimensions	53.4 x 68.6 mm