Adafruit Animated Snake Eyes Bonnet User Manual

Animated Snake Eyes Bonnet for Raspberry Pi

Created by Phillip Burgess

Last updated on 2021-02-09 11:20:59 AM EST

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Guide Contents

Guide Contents Overview Hardware Assembly

Compatible Devices

Plan a Head Software Installation Pi-Eyes Software Options Dry Run Raspberry Pi 4 (Experimental) Things to Know First Customizing the Hardware Analog Controls Buttons Software Changes Customizing the Look Changing the Python Code Changing Graphics Replacing Everything Using Just the Software Downloads Files Schematic Fab Print

Overview

The

Snake Eyes Bonnet

is a Raspberry Pi accessory for driving two 128x128 pixel OLED or TFT LCD

displays, and also provides four analog inputs for sensors.

It's perfect for making cosplay masks, props, spooky sculptures for halloween, animatronics,

robots...anything where you want to add a pair of animated eyes!

 PLEASE NOTE: the steps in this page currently DOES NOT WORK on the new Raspberry Pi 4 due to

lots of changes in the graphics subsystem. We have a work-around toward this, discussed on

https://learn.adafruit.com/animated-snake-eyes-bonnet-for-raspberry-pi/raspberry-pi-4-experimental

It’s a follow-on of sorts to another project:

Electronic Animated Eyes Using Teensy

3.2 (https://adafru.it/j6D).

The Teensy 3.2 is a

very

capable microcontroller, and the code for that project

squeezed every bit of space and performance from it. I had been experimenting with the Raspberry Pi as

an alternative…while it’s still very experimental, why not make that work available to others?

The Raspberry Pi offers some potential benefits:

Hardware-accelerated 3D graphics (OpenGL), including antialiasing.

A faster CPU, ample RAM and dual SPI buses could yield faster frame rates.

Standard graphics formats like JPEG, PNG and SVG can be decoded on the fly; no preprocessing

step.

The eye rendering code is written in a high-level language — Python — making it easier to

customize.

And some possible downsides to the Pi:

Raspberry Pi takes time to boot an operating system off an SD card, whereas Teensy is instant-on

with all code in flash memory, . The Pi also requires an explicit shutoff

procedure (usually (https://adafru.it/AJr)).

The Raspberry Pi is not as suitable for wearable applications…it’s larger, uses more power, and the

SD card makes it less rugged.

This is a somewhat technical and not-inexpensive project. Please read through everything first before

commiting. If it seems daunting, the original

Teensy Eyes (https://adafru.it/j6D)

are more “Arduino-like” to

build and customize, or other guides like

Animating Multiple LED Backpacks

(https://adafru.it/iwB) provide

a more approachable introduction to code and electronics with less of an investment.

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.

Hardware Assembly

 Don't forget, our Bonnet only comes with the PCB that lets you connect two displays. The two

displays are not included and must be purchased separately!

 Some situations don’t require the screens or Bonnet at all! See the “Using Just the Software” page if

planning a single, non-interactive HDMI eye.

Compatible Devices

The code for this project works only with our 128x128 pixel OLED (https://adafru.it/fXP) and

TFT (https://adafru.it/dXl) displays and 240x240 pixel IPS TFT (https://adafru.it/BhX) 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.

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 gradually working to improve performance

on these boards.

Plan a Head

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 (https://adafru.it/taM).

OLED (https://adafru.it/fXP), TFT LCD (https://adafru.it/dXl) or IPS TFT (https://adafru.it/BhX)

displays? OLEDs have a wide viewing angle and excellent contrast and color saturation, but they’re

somewhat pricey, and have a finite lifespan (albeit

many thousands

of hours). TFTs make good

economy displays if you’re okay with the slightly washed-out appearance. IPS TFT displays are in-

between in cost and

super

sharp!

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…

If using OLED display(s): use the “upper” rows (with the word

“OLED” between them).

There are 11 pins on the OLED breakout boards, which map

directly to the 11 pins on the bonnet board.

Make absolutely certain the wires are in the same order. “SI”

and “G” on the display board should go to “SI” and “G” on the

bonnet, and each pin in-between…no wires should cross.

If using TFT or IPS display(s): use the “lower” rows (with the

word “TFT” between them).

There are 11 pins on the TFT breakout boards, which map

directly to the 11 pins on the bonnet board.

Make absolutely certain the wires are in the same

order. “Vin” and “Lite” on the display board should go to “Vin”

and “Lite” on the bonnet, and each pin in-between…no wires

should cross.

 The 1.54" TFT has a 12th pin labeled "TE". DO NOT CONNECT THAT PIN TO THE BONNET. Only

connect the other 11 pins from "Vin" through "Lite"

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.)

Here’s a probable layout for a non-portable installation.

Straight header pins have been soldered to the bonnet board

and the displays, projecting “up” and “back,”

respectively. Two 11-pin female-to-female ribbon cables then

join everything.

This might be easiest to assemble (and disassemble), and the

straight header pins on the displays make them easy to re-

use in breadboard projects later.

…but that’s not the only option.

This TFT display has right-angle hader pins on the front of the

board (front, back, doesn’t matter as long as the wires

connect in the same order). This makes it very slim, but also a

fair bit taller.

And this OLED has an 11-pin ribbon cable directly soldered to

the board, no header pins at all. Again…front or back, ribbon

could go straight out or can double back across the board…it

all depends on your construction and space needs, as long as

the pin order is followed. This is the most space-efficient, but

requires patience and ace soldering skills, and isn’t easily re-

used in other projects.

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.

Adafruit Animated Snake Eyes Bonnet User Manual

Specifications and Main Features

Frequently Asked Questions

User Manual