- The code for this project works only with our 128x128 pixel OLED and TFT displays. Other displays such as our 160x128 TFT or various PiTFT displays ARE NOT SUPPORTED AT ALL, period, not even sorta.
- Any recent Raspberry Pi board with the 40-pin GPIO header should work. The very earliest Pi boards — Model A and B, with the 26-pin GPIO header — are not compatible. But…
- A Raspberry Pi 3 or Pi 2 is highly recommended. The code will run on a Pi Zero or other single-core Raspberry Pi boards, but performance lags greatly. We’re working on this and hope to have solid support for the smallest Pi boards in the future.
Before committing to any particular hardware, think your project through. There are some decisions to be made…
- One display or two? You don’t have to connect two displays…some of the most creative variants of the “Teensy eyes” had only a single eye.
- OLED or TFT LCD displays? OLEDs have a wide viewing angle and excellent contrast and color saturation, but they’re somewhat pricey. TFTs make good economy displays if you’re okay with the slightly washed-out appearance.
- What model of Raspberry Pi to drive it? The latest multi-core boards (like the Pi 3) have ample performance for smooth animation…but their size and power draw might make them best for stationary displays, like maybe a Halloween window prop. Costume and portable installations may fare better with the diminutive Pi Zero, though the animation will be much less smooth.
- Will the animation be running autonomously, or do you plan to control the eyes with a joystick and buttons? Will the pupils react to light? These require additional components.
There’s one more factor to consider: how do you want everything connected? Think about your intended installation. Is it temporary or permanent? Is space at a premium or do you have ample working room? These can influence your choice of wiring and connectors.
The breakout pins along the edge of each display board are wired up to matching pins on the bonnet boards. But you need the correct row for each display type…
There’s a common trope in science fiction stories: that there is no “up” or “down” in space. Wiring these displays is a little like that…it doesn’t matter if the wires or headers come out the front or back of the display breakout board, use straight or right-angle pins…as long as those wires get from the display to the bonnet in the same positions and order, everything’s good.
(As for up and down: right now the software assumes the displays are oriented with the breakout pins along the top edge; other rotations are not currently handled.)
If using “rainbow” ribbon cables: these have 10 colors, while the displays use 11 wires…this means the cables will have the same color wire along both edges. Therefore, DO NOT rely on a visual mnemonic like “black wire is ground” or “red wire is Vin,” because your cable may have two black wires, or two reds, or two anything. Instead, make sure to manually follow the first wire all the way from the bonnet to the display, make sure they line up right, then install the remaining wires in order.
If you’re really economizing for space, here’s a secret: only 7 wires are really needed…it’s just easier and less error-prone to solder a header at each end and plug all 11 wires straight through. If using the OLED display, the SC, SD, CD and 3V pins can optionally be skipped. If using TFT, the 3v3 SO, CCS and Lite pins can be skipped. Make certain the exact same pins are skipped at the bonnet end, don’t mix them up!
To ensure a clean signal from bonnet to displays, aim to keep your wiring short and tidy. Electrical interference can lead to animation glitches…we’ll explain on the next page how to dial that back if needed. It’s possible to use long ribbon cables (even a couple meters), but it invites problems with interference or signal reliability.
For optional features like joysticks, light sensors, blink and halt buttons, see the “Customizing the Hardware” page.
When finished soldering, you can peel the clear plastic covering off the displays. It’s meant to protect them in shipping and during soldering. But unlike the screen protector on a phone or tablet, it’s not optically pure and makes the display look cloudy.