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Archive for the ‘16×2 LCD’ Category

There’s nothing quite as annoying as duplicated effort. Having to jump through the same hoops over and over again is a perfect way to burn yourself out, and might even keep you from tackling the project that’s been floating around in the back of your mind. [Alain Mauer] found that he’d build enough Arduino gadgets that were similar enough he could save himself some time by creating a standardized piece of hardware that he can load his code du jour on.

He’s come to call this device the Arduino Nano QP (which stands for Quick Project), and now it’s part of the 2019 Hackaday Prize. [Alain] doesn’t promise that it’s the perfect fit for everything, but estimates around 85% of the simple Arduino projects that he’s come up with could be realized on QP. This is thanks to the screw terminals on the bottom of the device which let you easily hook up any hardware that’s not already on the board.

The QP board itself has the ubiquitous 16×2 character LCD display (complete with contrast control trimmer), seven tactile buttons arranged in a vaguely Game Boy style layout, and of course a spot to solder on your Arduino Nano. All of which is protected by a very slick laser cut acrylic case, complete with retained buttons and etched labels.

We’ve seen no shortage of handheld Arduino devices, but we have to admit, something about the utilitarian nature of this one has us intrigued. We wouldn’t mind having one of these laying around the lab next time we want to do a quick test.

The basic 16×2 LCD is an extremely popular component that we’ve seen used in more projects than we could possibly count. Part of that is because modern microcontrollers make it so easy to work with; if you’ve got an I2C variant of the display, it only takes four wires to drive it. That puts printing a line of text on one of these LCDs a step or two above blinking an LED on a digital pin on the hierarchy of beginner’s electronics projects.

What’s that? Even four wires is too many? In that case, you might be interested in this hack from [Vinod] which shows how you can drive the classic 16×2 with data and power on the same pair of wires. You’ll still need a microcontroller “backpack” for the LCD to interpret the modulated voltage, but if you’ve got an application for a simple remote display, this is definitely worth checking out.

The basic idea is to “blink” the 5 V line so quick that a capacitor on the LCD side can float the electronics over the dips in voltage. As long as one of the pins of the microcontroller is connected to the 5 V line before the capacitor, it will be able to pick up when the line goes low. With a high enough data rate and a large enough capacitor as a buffer, you’re well on the way to encoding your data to be displayed.

For the transmitting side, [Vinod] is using a Python script on his computer that’s sending out the text for the LCD over a standard USB to UART converter. That’s fed into a small circuit put together on a scrap of perfboard that triggers a MOSFET off of the UART TX line.

We actually covered the theory behind this technique years ago, but it’s always interesting to see somebody put together a real-world example. There might not be too many practical uses for this trick in the era of dirt-cheap microcontrollers bristling with I/O, but it might make a fun gag at your hackerspace.

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