Displays and Indicators

A box of screens for prototypes. Every project eventually runs into “how do I see what is going on in there”, and then the choice begins: show a number, draw a graph, or make do with a blinking LED.

Everything here is what you try that on, before ordering a display for your own board.

What is here and what for

• A TFT of about 3.5 inches — colour, backlit, connected by a ribbon. For an interface with pictures, graphs and buttons. It wants noticeably more pins and more memory than the rest.
• OLED modules around an inch — monochrome, over I²C or SPI, two to four wires. The usual choice for a small instrument: high contrast, no backlight needed, easy to wire. Some are on breakout boards, some are bare with an FPC tail — the latter for people laying out their own board.
• A 1602 character LCD — two lines of sixteen characters, parallel interface or an I²C backpack if one turns up. An old, simple and very predictable thing.
• 8 × 8 LED matrices — scrolling text, icons, simple animation.
• Seven-segment indicators — four-digit and single digits. For when you need to show a number and nothing else: a clock, a counter, a temperature.
• A bar graph — a column of segments for a level or a progress indication.

Worth knowing before you wire it up

• Voltage. Some modules are 3.3 V, some tolerate 5 V. Putting five volts on a three-volt OLED happens once. If there is no clear marking on the board, measure and read the datasheet.
• Interface. I²C is two wires and slow, SPI is more wires and fast, parallel is a lot of wires. For animation on a TFT the difference matters.
• The FPC tails on the bare displays are fragile. They must not be creased and must not be tugged: the traces inside break invisibly and the display simply stops working.
• Libraries. Almost everything here has a ready library for Arduino and STM32. Start with the library's example rather than your own code: that way you find out at once whether the module is alive.

How to use

1. Take a module and read the controller marking on the board — that is what you search for both the library and the datasheet with.
2. Wire it on a breadboard and check it with the library example.
3. Put the module back in the box, not in your pocket and not in your own desk drawer.
4. If a module does not work, put it aside separately and tell us, so the next person does not lose an evening to it.

The parts for building it up — jumpers, breadboards, wire — are in the component boxes.

Access

The container is in the hackspace room, so a plan that includes hackspace access is required. No induction is needed.