CHAPTER 4 ■ COMPLEX FLOWS: NODE-RED
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Internet Connectivity (Wireless)
The second section of the code defines variables, constants and functions that are going
to be used for connecting to the Internet . Use the code from Listings 2-7 , 2-8 , and 2-9
(Chapter 2 ) here.
Read Sensor Data
The third section of the code is provided in Listing 4-4 . It defines variables, constants, and
functions that are going to be used for reading sensor data.
The readSensorData() function reads data from Analog Pin A0, and the result is
between 0 and 1023. The greater the value returned, the brighter the light source. The
light sensor value is assigned to the lightValue variable.
Listing 4-4. Code for the Reading Light Sensor Data
int lightValue;
void readSensorData()
{
//Read Light Sensor Value
lightValue = analogRead(A0);
Serial.print("[INFO] Light Sensor Reading: ");
Serial.println(lightValue);
}
Data Publish
The fourth section of the code is provided in Listing 4-5 . It defines variables, constants,
and functions that are going to be used for creating and sending an HTTP request to the
server. This code is a slightly modified version of the HTTP GET that you developed in
Chapter 3 .
The main modification in this code is its ability to open and close a connection to
the server repeatedly. Apart from that, make sure to change the server and port values to
your Node-RED server’s values. The other changes include passing a lightValue variable
in the request and invoking the /lightSensorTweet URL.
Listing 4-5. Code for Starting the Node-RED Flow Using HTTP Request
//IP address of the HTTP server
char server[] = { "10.0.0.6" };
int port = 1880 ;
unsigned long lastConnectionTime s= 0;
const unsigned long postingInterval = 10L * 1000L;