Command Line LCD Arduino Interface

Liquid crystal displays are pretty awesome. Command line interfaces are very awesome. Hmm…

I started daydreaming at work about how to go about making hardware interface with an RSS feed. I have seen some projects that use Arduinos with ethernet shields to check Twitter, for example, but they seem unnecessarily bulky. Or clumsy. I spend a lot of time working on the command line, and love to put together dirty little scripts to solve problems. It sort of goes along the lines of ‘when you have a hammer, everything looks like a nail’…I figured that the same thing could be implemented with a little shell scripting and my trusty Arduino, sans anything complicated.

So far, so good.

I put together a sketch (after the bump) to drive my LCD, writing serial output to the screen. After verifying that the sketch worked via the Arduino IDE’s serial monitor, I popped open a CLI and got to work. FWIW, I am using Ubuntu 11.04 still…ctrl-alt-t pops open a terminal window…unity has me all over shortcuts these days. Anyhow, I was able to verify that I could echo text and direct it to the USB port that the Arduino was mounted to. No sweat.

As a proof of concept, I decided to display the number of times that I had the word “awesome” on swantron.com. Once the LCD was shown to work, the sky is the limit…see some regex, pipes, wget, and so forth in action:

Survey says:

Eleven “awesome”s. Awesome.
(Hit the bump for some code, an oddity, and more fun…)

So that is that. You could link two of these together for 160 characters…toss together a shell (or Python, etc.) and have a Twitter display, for example. Whatever you want to…gosh.

I did notice an odd “feature” of the Liquid Crystal library I used. For some reason, it wraps lines in an interesting fashion…

command line usage:
> echo “why does this library I am using wrap text wonky as hell?” > /dev/ttyUSB0

No idea why this is. Sort of confusing. Anyhow, the entire sketch is pretty straight forward. Did somebody say snippet?

// LCD sandbox
// https://swantron.com
// driving LCD from command line
// 2011

#include

// **Define pins**
// LCD RS – pin 12
// LCD R/W – pin 11
// LCD ENABLE – pin 10
// LCD BACK+ – pin 13
// LCD DATA4 – pin 5
// LCD DATA5 – pin 4
// LCD DATA6 – pin 3
// LCD DATA7 – pin 2
// LCD VSS, CONTRAST, BACK- – ground

LiquidCrystal lcd(12, 11, 10, 5, 4, 3, 2);

int backLight = 13; // Define pin for backlight

void setup()
{
pinMode(backLight, OUTPUT);
digitalWrite(backLight, HIGH); // Backlight level (LOW / HIGH)
lcd.begin(20,4); // (Columbs, Rows)
Serial.begin(9600);
}

void loop()
{
// when characters arrive over the serial port…
if (Serial.available()) {
// wait a bit for the entire message to arrive
delay(100);
// clear the screen
lcd.clear();
// read all the available characters
while (Serial.available() > 0) {
// display each character to the LCD
lcd.write(Serial.read());
}
}
}

We’ll see where this one ends up. This one might be a launching pad for a bigger and better thing. Stay tuned.