Writing in Place: A 16x2 Liquid Crystal Display (LCD) - Black on Yellowish Green

Writing in Place: A 16x2 Liquid Crystal Display (LCD) - Black on Yellowish Green

lcd
lcd

An onsite explanation would help. Something glowing right next to the gumball machine. 

The default: 16x2 Liquid Crystal Display(LCD). This yellowish green window is how hacked-together electronics communicate with the world.

There's not a lot of room for expression on one of these devices: just 2 lines of text, 16 characters each.

Most of the time, that's enough: an LCD like this is usually displaying:

  • Machine talk -- data from a sensor or circuit board; or
  • A terse message from a hacker to him- or herself: a small, hopeful prayer that things are working -- that circuits are making round trips.

Paste an image of one of these LCDs in Google Image Search, and it will return screenfuls of cascading, glowing rectangles, conveying messages that hopeful experimenters are sending to themselves: often "hello world," but also, "Is this working?" And of course, "All your base are belong to us."

You can get these LCDs from Chinese suppliers for $3 each; $2.75 each if you order more than 500.

I bought mine from Sparkfun, located outside Boulder, Colorado. It came with a "backpack" that smoothed out some of the interface issues.

So, officially, it's a SparkFun Serial Enabled 16x2 LCD - Black on Green 3.3V.

Here's what it looks like on the back:

After it arrived in the mail, I took it directly to Cambridge Hackspace on the very next Tuesday drop-in night.

Then I tried to send a message to the LCD: from my computer > the Particle cloud > a Photon > the LCD.

Nothing.

Was it the LCD? The computer/cloud connection? The Particle Photon?

I was getting nowhere... until a young man with a strong Russian accent sat down next to me, curious about the LCD and the splayed wires.

He was well-dressed. As we both looked down at my project I noticed that he was wearing black leather shoes that came to stylish points.

He (I never got his name; I don't think he mentioned it) said he was at the Hackspace to work with an MIT-based team on an upcoming robot competition, but when he examined the LCD and the Photon, he said that it should work.

Now he was engaged. He began to work on the code in Particle's integrated development environment (IDE) with an intensity that bordered on righteous anger.

Slowly, the LCD succumed: text messages began flickering on the screen: first sporadically, then more consistently as he adjusted the wiring and the code. All this took about 12 minutes.

By the time he returned to his robot project, I was sending tiny, tentative messages.

Unfortunately, they looked like messages on my coffeemaker. Let's just say they didn't pop. They seemed, in fact, to recede... back to the 1970s. 

So I started looking around for something more... Times Square. 

Next - A Tragically Beautiful LED Matrix