Course: Internet of Things: Tutorial: Arduino Programming

Setting up Arduino Environment:

To interact with Arduino board from our system we need to setup required software installed in the system. Follow below steps to install Arduino IDE,

Download and install arduino IDE from the link: https://www.arduino.cc/en/Main/Software
After installation, add the ESP8266 package by following these steps:

In the Arduino IDE, open the Preferences window.

Enter http://arduino.esp8266.com/stable/package_esp8266com_index.json in the Addiotional Board Manager URLs text field.

Open Board Manager from Tools and install esp8266 platform.

Setup ESP8266 support: Select Tools --> Board --> NodeMCU 1.0(ESP-12E Module)
CPU Frequency: Select Tools --> CPU Frequency --> 80 MHz
Upload Speed: Select Tools --> Upload Speed --> 115200
Finally selecting a port: Select one of the ports available in the list: Tools --> Port

Following diagram represents the ESP8266MOD and its configuration information, it helps to make connections easier (pins, GPIOs etc.)

1. Flashing LED Circuit:

Arduino ESP8266MOD provides easy environment to do experiments with minimum number of connections.

Test1 - External LED:

The following code works for GPIO#7 (pin#13 or D7),

// the setup function runs once when you press reset or power the board
void setup() {
// initialize digital pin 13 as an output.
pinMode(13, OUTPUT);
}

// the loop function runs over and over again forever
void loop() {
digitalWrite(13, HIGH); // turn the LED on (HIGH is the voltage level)
delay(750); // wait for a second
digitalWrite(13, LOW); // turn the LED off by making the voltage LOW
delay(750); // wait for a second
}

Output: Now, you can see that the external LED blinks, with delay as 750 milliseconds.

Test2 - Internal LED:

The following code works for pin#16,

// the setup function runs once when you press reset or power the board

void setup() {

// initialize digital pin 13 as an output.

pinMode(16, OUTPUT);

}

// the loop function runs over and over again forever

void loop() {

digitalWrite(16, HIGH); // turn the LED on (HIGH is the voltage level)

delay(500); // wait for a second

digitalWrite(16, LOW); // turn the LED off by making the voltage LOW

delay(500); // wait for a second

}

Output: Now, you can see that the internal LED blinks, with delay as 500 milliseconds.

2. Temperature/Humidity Sensor Circuit:

The DHT sensor is much easier to connect:

Plug the pin number 1 to the Arduino’s 3.3V pin
Pin number 4 to GND
Pin number 2 to Arduino pin 13(D7 or GPIO#7)
Finally, put the 10K resistor between the sensor pins number 1 and 2

Code:

// Include required libraries
#include <SPI.h>
#include <string.h>
#include "DHT.h"

// DHT11 sensor pins
#define DHTPIN 13
#define DHTTYPE DHT11

// DHT instance
DHT dht(DHTPIN, DHTTYPE);

void setup(void)
{

// Initialize DHT sensor
dht.begin();

Serial.begin(115200);

}

void loop(void)
{

// Measure the humidity & temperature
float h = dht.readHumidity();
float t = dht.readTemperature();

// Transform to String
String temp = String((int) t);
String hum = String((int) h);

Serial.print("Temperature: ");
Serial.println(temp);
Serial.print("Humidity: ");
Serial.println(hum);
Serial.println("");
delay(1000);
}

The following code interacts with Arduino board and read the responses of DHT11 and displays the output. To see the result, Select Tools --> Serial Monitor

Final report is shown below,

ARRAYS - Test with more LEDs:

A serial of LEDs connected, and tested for blink one after another

Following code enables the serial(array) of LEDs to turn on:

int timer = 200; // The higher the number, the slower the timing.
int ledPins[] = {
5, 4, 2, 14, 12, 15
}; // an array of pin numbers to which LEDs are attached
int pinCount = 6; // the number of pins (i.e. the length of the array)

void setup() {
// the array elements are numbered from 0 to (pinCount - 1).
// use a for loop to initialize each pin as an output:
for (int thisPin = 0; thisPin < pinCount; thisPin++) {
pinMode(ledPins[thisPin], OUTPUT);
}
}

void loop() {
// loop from the lowest pin to the highest:
for (int thisPin = 0; thisPin < pinCount; thisPin++) {
// turn the pin on:
digitalWrite(ledPins[thisPin], HIGH);
delay(timer);
// turn the pin off:
digitalWrite(ledPins[thisPin], LOW);

}

// loop from the highest pin to the lowest:
for (int thisPin = pinCount - 1; thisPin >= 0; thisPin--) {
// turn the pin on:
digitalWrite(ledPins[thisPin], HIGH);
delay(timer);
// turn the pin off:
digitalWrite(ledPins[thisPin], LOW);
}
}

BUTTON Test:

A button connected to ESP8266MOD as follows,

One pin of button is connected to the GND(ground)
Another end of button is connected to the one end of 220 Ohms resistor
Other end of resistor is connected to 3.3V pin
Finally, LED is connected as anode to GPIO pin annd cathode to GND

Code:

// set pin numbers:
const int buttonPin = 14; // the number of the pushbutton pin
const int ledPin = 13; // the number of the LED pin

// variables will change:
int buttonState = 0; // variable for reading the pushbutton status

void setup() {
// initialize the LED pin as an output:
pinMode(ledPin, OUTPUT);
// initialize the pushbutton pin as an input:
pinMode(buttonPin, INPUT);
}

void loop() {
// read the state of the pushbutton value:
buttonState = digitalRead(buttonPin);

// check if the pushbutton is pressed.
// if it is, the buttonState is HIGH:
if (buttonState == HIGH) {
digitalWrite(ledPin, HIGH);
} else {
digitalWrite(ledPin, LOW);
}
}

Difference setting up and programming interface using two different source ( laptop and pi ):

I wanted to try to get Raspberry talking to an Arduino over USB using Python.

There is a Python library for serial communications called 'pySerial' which has history with Arduino. You can find more information here: http://playground.arduino.cc/Interfacing/Python

First, install Arduino: $ sudo apt-get install arduino
Next, install the nanpy source: This is needed to later build the new Arduino firmware:

1 $ cd ~

2 $ curl -O https://pypi.python.org/packages/source/n/nanpy/nanpy-v0.8.tar.gz

3 $ tar xvf nanpy-v0.8.tar.gz

4 $ rm nanpy-v0.8.tar.gz

Now install the required Python libs:

1 $ sudo pip install nanpy

2 $ sudo pip install pyserial

Hook up your Arduino to one of the Pi’s USB ports, and create/upload the new firmware (using an Arduino Uno as an example):

1 $ cd ~/nanpy/firmware

2 $ export BOARD=uno

3 $ make

4 $ make upload

NOTE: When I am trying to run make upload, the command throws an error. Later I understand that the downloaded arduino IDE is of 1.0.x version instead 1.6.x version. In this old version of arduino IDE, there is no setup for ESP8266MOD. When I am trying to install ESP8266 plugin there is no option to go to Board Manager in Tools. Hence I could not able to do test on raspeberry pi - arduino integration through with old version. I will try to install newer version and make necessary installation and setup, as well as the basic tests of raspberry pi - arduino integration(data exchange).

References:

http://www.akeric.com/blog/?p=2420
http://www.doctormonk.com/2012/04/raspberry-pi-and-arduino.html
http://playground.arduino.cc/Interfacing/Python
http://www.instructables.com/id/The-Raspberry-Pi-Arduino-Connection/
http://blog.oscarliang.net/connect-raspberry-pi-and-arduino-usb-cable/
http://www.seeedstudio.com/recipe/166-basic-pi-lt-gt-arduino-communication-over-usb.html
http://playground.arduino.cc/Linux/Ubuntu
http://blogspot.tenettech.com/?p=2723
http://razzpisampler.oreilly.com/ch10.html
http://spellfoundry.com/sleepy-pi/setting-arduino-ide-raspbian/

Course: Internet of Things

Sunday, February 7, 2016

Tutorial: Arduino Programming

Contents:

Setting up Arduino Environment:

1. Flashing LED Circuit:

Output: Now, you can see that the external LED blinks, with delay as 750 milliseconds.

2. Temperature/Humidity Sensor Circuit:

Difference setting up and programming interface using two different source ( laptop and pi ):

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