3

FORGE

computer board and the sensor of a couple of metres
works fine.

SOFTWARE
The simplest way to program ESP8266 boards like the
NodeMCU is via the Arduino IDE. The core Arduino IDE
package must be extended with a board manager to
work with the ESP8266. Many sketches and libraries
developed for the Arduino series of computers can be
used on the ESP8266 – a huge advantage, given the
wealth of Arduino applications. The sketch (Arduino
program) relies on a library written to access the
TLS2561 sensor by the people at SparkFun. Setting
up the Arduino IDE and loading the SparkFun library is
described in the box on page 106.

HANDLING THE SOLAR SENSOR
First attach the libraries needed for the WiFi, the solar
sensor, and the I^2 C interface.

#include <SparkFunTSL2561.h>

#include <Wire.h>

Next, enter the calibration for the sensor. The
number, 3000, in the code is for indoor light for initial
investigation. Once you have calibrated your sensor,
change this to suit.

float solcalib=1000.0/3000;

Tell the ESP8266 how the I^2 C hardware is connected.

#define SDA 0 // GPIO0 / D3

#define SCL 2 // GPIO2 / D4

Create an instance of the light sensor and set the
highest reading that will be likely.

SFE_TSL2561 light;
const float solarMax = 1000.0;
This next section is run once from the main setup
function and collects together all the instructions
required to set up the solar sensor.

void setup_solarirradiance() {

boolean gain = 0;

unsigned int sitime;

unsigned char time = 0; // time 13.7

milliseconds

light.begin(); // Initialize the

TSL2561

delay(1000);

light.setPowerUp();

}

The following function is used to take readings from

the sensor.

float reading_totalsolar() {

unsigned int sdata0, sdata1;

const float error =9999.0;

if (light.getData(sdata0,sdata1))

{

return solcalib*sdata0;

}

else

{

return error;

}

}

NODEMCU PHONE HOME

Setting up the WiFi on an ESP8266 device is

straightforward, but you will have to enter details of your

WiFi network to make this section work. In particular,

you will need to enter the network name in the ssid

variable and the network password in password. The

other settings may should suit most networks, but if

your router has a different IP address or the address

192.168.0.186 is already assigned, you will need to

change the other settings.

(If you are unsure what IP address your router has,

try using the incredibly useful, free smartphone app,

Fing, to see all the devices on your WiFi network and

their IP addresses.)

#include <ESP8266WiFi.h>

const char* ssid = “********”; // Wi-Fi network

const char* password = “*****”;// Wi-Fi password

IPAddress ip(192,168, 0, 186); // static IP

IPAddress gateway(192,168,0,1); // router IP

IPAddress subnet(255,255,255,0);

Figure 1

ESP8266 website

for solar data

526

Solar Irradiance

FSD 10000 W/m/m