TweeterBie: Display Latest Tweets on 16X2 LCD using CubieBoard A 20 and Arduino

The TweeterBie is a device consisting of

1. CubieBoard A20 (CubieBoard 2)

2. Arduino Uno or any other compatible boards (I am using freeduino)

3. 16X2 LCD Display

4. Internet Connection

The goal of the project is to display latest tweets on the 16×2 Display using the above components.

The Software Downloads required are:

1. Phoenix / Live Suite, Live suite is for MAC and LINUX and Phoenix is for Windows

2. An Operating System / Firmwareto Boot on CubieBoard preferably Ubuntu Flavoured

a. Cubieez (I am Using this for this Project) around 550MB (prebuilt X11VNC)

b. Cubian

c. Lubuntu and more..

3. A Putty SSH Client to SSH into the CubieBoard.

4. Termite a serial terminal emulator or any other client

5. Advanced IP Scanner or Angry IP Scanner

We need a Linux and preferably an Ubuntu based operating system on which we can run python and use serial and socket connection to constitute a TweeterBie.

There are two things one can do at this point:

1. We can overwrite the NAND Flash with a Linux Operating System.

2. We can use a MicroSD card burn the OS on to it and boot the CubieBoard in Linux.

The step by step procedure for the above task is available in websites for CUBIEEZ or in other OS related websites.

In my configuration I had No Spare Mouse or Keyboard, No Ethernet Connectivity, only a Wi-Fi Dongle and a USB to RX-TX Converter with connecting wires

Fig. 1: Image showing Wi-Fi Dongle and USB to RX-TX Converter

For this first I installed the Termite Serial terminal emulator, connected my TTL to USB converter to the PC, installed all required drivers for the same and kept it ready to initialize communication.

Next in the TTL to USB converter end I took three wires- one from each of the Rx, Tx and Gnd Pin and connected them to the corresponding pins on the Hardware Debug Serial Interface provided on top of the CubieBoard.. Leave the VCC in open. Also note that Connecting 5v will damage the CubieBoard.

Fig. 2: Image showing connections of USB to RX-TX Converter with Cubieboard A20

Now open the Termite in your PC and choose settings.

Select the appropriate COM port (In my case it’s COM4). Set the following parameters:

Baud rate: 115200

Databits : 8

Stop bits : 2

Parity : None

Transmitted text: Append CR + LF as shown in above figure.

Note: You can also use just LF or CR but that depends on the OS you are using.

Press enter on the Keyboard by keeping cursor in the text box at the bottom of the TERMITE.

Now the screen presents login shell:

Enter “cubie” as user name and press enter (or click on send), when asked for password type “cubieboard” and press enter (or click on send).

This will bring us to the Cubie Shell to program and execute all our future programs.

Type “sudoifconfig” and press enter.

When asked for the password, from now on use “cubieboard”.

Or give “SU” first then enter the password as “cubieboard” this gives you root access so that you don’t need to use sudo anymore.

And you can run all shell commands under the root user in this terminal window.

Assuming you have a monitor supporting the HDMI or DVI input, a USB mouse, and a USB keyboard you need not have SSH to the board. You just have to connect them and start programming.

Programming

Arduino

It is assumed that reader gone through how to start with arduino and LCD interface with arduino .

It’s a common knowledge to choose Arduino for most of the embedded systems due to its simplicity in programming and vast amount of resources to get the most in small duration of time.

So connect the Arduino board to your desktop/Laptop (from now on called as PC) and fire up the Arduino Software.

Now open the program Examples > Liquid Crystal > Hello World as shown below.

Fig. 3: Screenshot of Arduino IDE showing navigation to sample code for Liquid Crystal Display

Make all the pin connections as described in the program comments at the beginning.

I have represented it in the Circuit Diagram for reference.

Now the LCD module is running in a 4 bit Mode instead of 8 bit mode.

Given that the data transfer takes twice as long but it’s sufficient for the TweeterBie.

Arduino Code has been Re-Engineered.

The attached code change introduces the scroll effect on the text to be displayed.

Note: The attached code has been attached as INO file

After dumping the code and executing with “ENGINEERING GARAGE” in Serial Port

Fig. 4: Image of Cubieboard A20 and Arduino based TweeterBie showing initial messages

Now we will need a way of communicate with the Arduino and send data.

I have chosen python for scripting.

Cubieez has a preinstalled version of PYTHON to test, open terminal and type as follows

python

Once the terminal changes to python port as >>>

It signifies that PYTHON is installed now to exit the prompt use

>>>exit()

There is a tool called pySerial which can be used for the purpose of serial communication. More documentation can be found here

Now, before we install pySerial we need PIP to be installed. This makes it easier to install the python libraries in the repositories.

To install PIP follow the instructions

Once you install pySerial you can use the miniterm which comes along with it.

To run the miniterm type the following command in the terminal.

Let’s look at the ports available in the CubieBoard

Ø python -m serial.tools.list_ports

this will list the available ports

This Introductory tutorial gives a good idea on how to use the pySerial.

My Arduino is connected through USB.

Fig. 5: Prototype of Cubieboard A20 and Arduino based TweeterBie

So the output of the previous command will now be:

Fig. 6: Screenshot of Mini Term application showing python commands

Ok let’s fire up mini term with port ttyUSB0 and baud rate of 9600. Make sure you run it in root.

The command for that is python -m serial.tools.miniterm <port name>

sudopython -m serial.tools.miniterm/dev/ttyUSB0

sudopython -m serial.tools.miniterm–p /dev/ttyUSB0 –b 9600

Fig. 7: Screenshot of Mini Term application showing execution of python commands

Whatever you type it will be displayed on the LCD. (It’s “HELLO” the O is right behind…)

Fig. 8: Image of Cubieboard A20 and Arduino based TweeterBie showing a received tweet

Configuration

Ok since the Display part is up and running we will configure the TWEETER part of TweeterBie.

The following can be done directly from the CubieBoard but I am doing this on my PC.

In order to access the tweets we need to establish a connection to twitter servers, authenticate ourselves as the user as well as the CubieBoard device and use API calls to get the latest tweets. The tutorial mentioned below deals with just that from basics.

In order to create access to TweeterBie go to https://dev.twitter.com/ and sign in with the Twitter credentials.

As we are using Python for coding and there is well built API library for Twitter access in python it’s called TweePy, for more info TweePy use this documentation and this Auth tutorial.

First thing we need here is to install the TweePy on to CubieBoard.

Since we already have PIP installed it’s very easy to install TweePy.

Use the following command on the terminal.

sudopip install tweepy

cd tweepy

This changes the directory to tweepy

sudopython setup.py install

Now we install the tweepy.

Let’s create the work directory “TweeterBie”

mkdirTweeterBie

And let’s change the command prompt to point inside the directory

cd TweeterBie

Now we will create a file to store our python code.

nano TweeterBie.py

In the NANO Editor enter the following code referred from this site http://stackoverflow.com/questions/7714282/return-actual-tweets-in-tweepy,

weeterBie.py

importtweepy# imports TweePy Library

importserial # imports pySerial Library

importtime # use of delay statement needs this library

ser = serial.Serial(‘/dev/ttyUSB0’, 9600, timeout=1)

# Consumer keys and access tokens, used for OAuth> Tweeter User Dependent

consumer_key = ‘MfRPzXL7gsfxsB1T1Tdab42lY’ # API KEY

consumer_secret = ‘O9k5dVSbIxYM4GCQj0IKnRdGkFTKGwaLLEunz2v9jwZriFh2qQ’

access_token = ‘2526693469-raqqlVcj6jMV36AshYVAX48jvt8Q3BvSuEkrjOM’

access_token_secret = ‘CbvbGGxTl50dTishhxjfDklNATHkKaiaedv5zWpVzH86p’

# Consumer keys and access tokens, used for OAuth ends here

# OAuth process, using the keys and tokens

auth = tweepy.OAuthHandler(consumer_key, consumer_secret)

auth.set_access_token(access_token, access_token_secret)

# Creation of the actual interface, using authentication

api = tweepy.API(auth)

time.sleep(3); # sleep 3 seconds to initiate arduino

public_tweets = api.home_timeline()# access all tweets from timeline

for tweet in public_tweets:

printtweet.text # prints the all Tweets on terminal

ser.write(tweet.text.encode(‘utf-8’)) # prints text on LCD

time.sleep(8); # Sleep for 8 seconds between tweets

ser.close() # close port

Now Save and Exit .save = ctrl^o and Exit= ctrl^X

If you need regular update, use the code given below.

# File Editor : GNU nano 2.2.6 File:

SuperLoop_TweeterBie.py

importtweepy# imports TweePy Library

importserial # imports pySerial Library

importtime # use of delay statement needs this library

ser = serial.Serial(‘/dev/ttyUSB0’, 9600, timeout=1)

# Consumer keys and access tokens, used for OAuth> Tweeter User Dependent

consumer_key = ‘MfRPzXL7gsfxsB1T1Tdab42lY’ # API KEY

consumer_secret = ‘O9k5dVSbIxYM4GCQj0IKnRdGkFTKGwaLLEunz2v9jwZriFh2qQ’

access_token = ‘2526693469-raqqlVcj6jMV36AshYVAX48jvt8Q3BvSuEkrjOM’

access_token_secret = ‘CbvbGGxTl50dTishhxjfDklNATHkKaiaedv5zWpVzH86p’

# Consumer keys and access tokens, used for OAuth ends here

# OAuth process, using the keys and tokens

auth = tweepy.OAuthHandler(consumer_key, consumer_secret)

auth.set_access_token(access_token, access_token_secret)

# Creation of the actual interface, using authentication

api = tweepy.API(auth)

time.sleep(3); # sleep 3 seconds to initiate Arduino

while True:

public_tweets = api.home_timeline()# access all tweets from timeline

for tweet in public_tweets:

printtweet.text # prints the all Tweets on terminal

ser.write(tweet.text.encode(‘utf-8’)) # prints text on LCD

time.sleep(8); # Sleep for 8 seconds between tweets

time.sleep(30); # sleep 30 Seconds before accessing the API again

ser.close() # close port

Now let’s update the Twitter Tweets and make sure that it’s working!!!

Warning: Please don’t give tweets larger than 22 characters…!!

This results line shifting at this point as shown below.

New Tweets:- but displayed in reverse order

1. Welcome to Twitter

2. You rock lol

3. Hi@engineersGarage

4. This is the 4th Tweet

The Outcome of the above tweets by TweeterBie is given below.

Project Source Code

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#include   // already there in the sketch for LCD display

// initialize the library with the numbers of the interface pins
LiquidCrystallcd(12, 11, 5, 4, 3, 2);
charinData[141]; // Allocate some space for the string max of 140 charcters in Tweets
charinChar; // Where to store the character read from serial port
byte index = 0; // Index into array to point the memory location
bytebytesrecvd = 0; // counter to check the incoming bytes

void setup() {
Serial.begin(9600);  // Serial Port to send the characters to be displayed
Serial.write("Power On");   // Power up Signalling on the Debug port after establishing connection

lcd.begin(16, 2);    // set up the LCD's number of columns and rows
lcd.print("hello, world!");  // Print a message to the LCD Sample from old sketch
delay(1000); // Time lag until message is read out of the LCD
lcd.setCursor(0, 0); // Set LCD cursor to Home Position.
index = 0; // Set character Indexing position to nil (zero)

lcd.setCursor(0, 0); // bring back cursor to home
lcd.print("Latest Tweet: "); // Display the Header on First Line
lcd.setCursor(16, 1); // Go to last column of the Second line and wait for Characters to appear.
}
// This ends the Setup of the Arduino , Now to create the Super Loop
void loop() {
index = 0; // always reset to zero at the beginning of data reception
while(Serial.available() > 0) // Don't enter the section unless data is available to read
   { 
if(index < 140) // One less than the size of the array get only 140 characters
       {
inChar = Serial.read(); // Read a character
inData[index] = inChar; // Store it in “inData” array
index++; // Increment where to write next increment the index
inData[index] = ''; // Add terminating character (Null character) for the next position
delay(5); // give 5 milliseconds gap to avoid data corruption
bytesrecvd = index; // get the total count of bytes received
       }
   } // keep loping until data is available

lcd.clear();  // now clear the LCD of previous Data
lcd.setCursor(0, 0); // Go to Home Position
lcd.print("Latest Tweet: "); // write the latest tweet header on first line
lcd.setCursor(16, 1); // go to end of line on second row
lcd.autoscroll(); // start auto scroll (the problem is it will rotate both rows)

for (intthisChar = 0; thisChar
 
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