Pieced together from many different sources, the following scripts will allow you to display the Twitter public timeline, the top 20 Twitter trending topics and the current weather on your Arduino LCD screen. This is done with a PHP script and an Arduino connected to OS X via USB.
You can download the scripts as a zip file.
The Arduino Program
The tricky part of this project was getting the text to scroll up the two line LCD screen. In the Arduino program, we’re looking to see if a line of text has a special character prefixed to it. Text prefixed with ‘!’ will place the text on line 1. Text prefixed with ‘@’ will place the text on line 2. Sending the ‘^’ character clears the screen.
#include <liquidcrystal.h>
#include <wstring.h>
// initialize the library with the numbers of the interface pins
LiquidCrystal lcd(2, 3, 4, 9, 10, 11, 12);
void setup() {
analogWrite(5, 100); // Set LCD contrast level (0-255)
lcd.begin(16, 2); // Set the LCD's number of rows and columns
Serial.begin(9600); // Initialize communication with serial(USB) port.
lcd.print("Hello."); // Print welcome message to LCD.
}
int bufferArray[250]; // Our array to store characters arriving from serial port.
int output = 0;
int i = 0;
void loop() {
int count = Serial.available();
if (Serial.available() > -1) {
delay(1000);
for (i=0; i<count ; i++) {
bufferArray[i] = Serial.read(); // Put into array
output = 1; // Show new data has been recieved
}
}
if (output != 0) { // If new bytes have been recieved
int position = 0;
if (bufferArray[0] == '!') { // Print on first line if message begins with '!'
lcd.clear();
lcd.setCursor(0,0);
position = 1;
} else if (bufferArray[0] == '@') { // Print on second line if message begins with '@'
lcd.setCursor(0,1);
position = 1;
} else if (bufferArray[0] == '^') { // Clear screen if message begins with '^'
lcd.clear();
lcd.setCursor(0,0);
position = 1;
} else {
lcd.clear();
lcd.setCursor(0,0);
}
int j;
for (j = position; j < count; j++) {
lcd.write(bufferArray[j]);
}
output = 0; // Don't print on next iteration
memset(bufferArray, 0, count);
count = 0;
}
}
The PHP Script
With those rules established, our PHP script can handle the rest. I’m using fun classes like wordwrap and explode to break long strings of text into LCD width chunks that are placed into an array, prefixed with our placement characters, and fed to the Arduino.
<?php
// Include the PHP Serial class.
include "php_serial.class.osx.php";
//Define the serial port to use
define('SERIALPORT','/dev/cu.usbserial-A900adK5');
// Weather
$zipcode = 37211;
$title = "Nashville WX.";
// Setup the serial connection
$serial = new phpSerial;
$serial->deviceSet(SERIALPORT);
$serial->confBaudRate(9600);
// Time
$lastTime = date('D M j H:i:s Y');
$lastTime = strtotime($lastTime);
// Scroll text up LCD screen
function scrollChunks($message) {
global $serial;
$serial->deviceOpen();
for ($i=0; $i<count ($message); $i++) {
if ($i==0) {
$serial->sendMessage($message[$i]);
} else if ($i&1 && $i!=0) { // If $i is odd and not zero
$serial->sendMessage($message[$i]);
sleep(1);
$message[$i] = substr_replace($message[$i], "!", 0, 1); // Print on top line !
$serial->sendMessage($message[$i]);
} else if (!($i&1) && $i!=0) { // If $i is even and not zero
$message[$i] = substr_replace($message[$i], "@", 0, 1); // Print on top line @
$serial->sendMessage($message[$i]);
sleep(1);
$message[$i] = substr_replace($message[$i], "!", 0, 1); // Print on top line !
$serial->sendMessage($message[$i]);
}
echo $message[$i]."\n";
sleep(1);
}
sleep(1);
$serial->sendMessage(" ");
$serial->deviceClose();
}
// Wordwrap our text to lines no more than 15 characters long.
// The LCD displays 16 characters at a time, minus a space for our
// placement character.
function segmentString($t) {
$chunks = wordwrap($t, 15, "\n", true);
$chunks = explode("\n", $chunks);
// Alternate each line with '!' and '@'
for ($i=0; $i<count ($chunks); $i++) {
if ($i&1) {
$chunks[$i] = "@".$chunks[$i];
} else {
$chunks[$i] = "!".$chunks[$i];
}
}
scrollChunks($chunks);
}
function displayRSS() {
global $serial;
global $title;
echo "Display only: ".$title."\n";
sleep(3);
$serial->deviceOpen();
$serial->sendMessage($title);
sleep(240);
$serial->sendMessage("^");
sleep(3);
$serial->deviceClose();
}
function pullWXRSS() {
global $zipcode;
$yql = "http://query.yahooapis.com/v1/public/yql?q=select%20*%20from%20weather.forecast%20where%20location%3D".$zipcode."&format=json";
$session = curl_init($yql);
curl_setopt($session, CURLOPT_RETURNTRANSFER,true);
$json = curl_exec($session);
$json_output = json_decode($json,true);
global $serial;
global $title;
$title = $json_output['query']['results']['channel']['item']['condition']['temp']."F ".$json_output['query']['results']['channel']['item']['condition']['text'];
echo "Pull and Display: ".$title."\n";
echo "Waiting a few seconds to display on Arduino...\n\n";
sleep(5);
$serial->deviceOpen();
$serial->sendMessage($title);
sleep(240);
$serial->deviceClose();
sleep(3);
}
// Display current weather from Yahoo! YQL
function displayWX() {
global $lastTime;
global $title;
$currentTime = date('D M j H:i:s Y');
$currentTime = strtotime($currentTime);
echo "\n\n\n\nCurrent Time: ".$currentTime."\n";
echo "Last Time: ".$lastTime."\n";
$timeDiff = $currentTime - $lastTime;
echo "Time Difference: ".$timeDiff."\n";
// 1 hour = 3600
if ($timeDiff>=3605 || $title == "Nashville WX.") {
echo "It's been an hour. Pulling WX.\n";
$lastTime = $currentTime;
pullWXRSS();
} else {
echo "An hour has not passed. Displaying old WX.\n";
displayRSS();
}
displayPubTimeline();
}
function displayPubTimeline() {
$jsonurl = "http://api.twitter.com/1/statuses/public_timeline.json";
$json = file_get_contents($jsonurl,0,null,null);
$json_output = json_decode($json,true);
foreach ($json_output as $tweet) {
$name = $tweet['user']['screen_name'];
$text = $tweet['text'];
echo "\n\n\n".$name."\n";
echo $text."\n\n";
global $serial;
$serial->deviceOpen();
$serial->sendMessage("Twitter User:");
sleep(1.5);
$serial->sendMessage("@".$name);
echo "@".$name."\n";
sleep(2);
$serial->deviceClose();
if (strlen($text) > 16) {
segmentString($text);
} else {
$serial->deviceOpen();
$serial->sendMessage($text);
$serial->deviceClose();
}
sleep(5);
}
sleep(5);
displayTopTrends();
}
function displayTopTrends () {
$jsonurl = "http://api.twitter.com/1/trends/daily.json";
$json = file_get_contents($jsonurl,0,null,null);
$json_output = json_decode($json,true);
$json_output = current($json_output['trends']);
global $serial;
$serial->deviceOpen();
$serial->sendMessage("The top 20");
sleep(1);
$serial->sendMessage("@Twitter trends:");
$serial->deviceClose();
sleep(3);
echo "\n\nTwitter Trends\n\n";
foreach ($json_output as $trend) {
$trendname = $trend['name'];
echo $trendname."\n";
$serial->deviceOpen();
$serial->sendMessage("^".$trendname);
$serial->deviceClose();
sleep(15);
}
$serial->deviceOpen();
$serial->sendMessage("^");
sleep(1);
$serial->deviceClose();
sleep(3);
displayWX();
}
displayWX();
?>
PHP Serial Class
The PHP script requires an OS X specific serial class to talk with the Arduino board. I’m using this serial class by Rémy Sanchez, modified by Andrew Hutchings. You’ll need to define your serial device (which you can find in /dev). It should look something like /dev/cu.usbserial-A900adK5.
Bash Start-up File
In addition, due to the way OS X handles communication over the USB connection (you can read more about it here) we need to run a sleep command to prevent the Arduino from resetting itself each time you send data to it.
#!/bin/bash
nohup sleep 36000 < /dev/cu.usbserial-A900adK5 &
php tweet-arduino.php
That’s it. Pass the Arduino program to your Arduino, change the name of your serial device in the PHP script and these scripts should run right out of the box.
