Steampunk portable Rasp Pi lunchbox

Moveable Feast

© Lead Image © ateliersommerland, 123RF.com

© Lead Image © ateliersommerland, 123RF.com

Article from Issue 238/2020
Author(s):

A lunchbox-style portable Raspberry Pi computer provides external control for a steampunk robotic skull.

As "Dr. Torq," I play a moderately eccentric 1880s-era inventor who develops physical computing projects with modern off-the-shelf parts; then I share lessons learned through how-to articles and conference tech talks. The steampunk aesthetic inevitably generates a lot of curiosity, so it naturally figures prominently in many of my designs. One of my designs, a robotic skull, needed additional controls, so I decided to create a steampunk lunchbox-style portable computer.

Why a Steampunk Lunchbox Computer?

Hedley, my steampunk robotic skull (Figure 1), originally had an onboard Raspberry Pi brain. The Rasp Pi sent speech data from a processing program to an Arduino, actuating the jaw. It also had a JeVois smart machine vision sensor, and I used a webcam program like luvcview [1] to monitor whatever the sensor recognized. I built a little outboard monitor to watch the vision sensor feed, effectively turning Hedley into a stealth desktop computer. Hedley even appeared with me at a couple of conferences and ran my LibreOffice session slides. Although Hedley worked, it always felt kind of clunky.

Figure 1: Hedley, the steampunk robotic skull.

This led to the idea of using a separate portable Linux computer to direct Hedley's actions while also supporting conference tech talk activities. A lunchbox layout style would allow ample freedom for over-the-top design elements and give a cool "open frame" steampunk look. Here, I look at the lunchbox machine in its present form, the software, and how it all came into "sitting on the table" reality. In fact, this article was written with the lunchbox notebook (Figure 2).

Figure 2: The steampunk Linux lunchbox computer showing this article in LibreOffice Writer.

Of Course It Runs Linux

Linux powers most of the small-footprint single-board computers (SBCs) these days, and I think Linux is the reason they have become so popular in nanocomputer projects. With the considerable computing power of a Raspberry Pi, you can automate many jobs. The latest model 4 has 4GB of RAM, a quad-core chip, high-resolution dual-monitor outputs, USB 3, and onboard WiFi. (See Table 1 for the hardware components.) It can do just about anything a current budget notebook can do, except maybe super-heavy video or graphics editing. I paid $55 for the 4GB model. Of course, the first step in building a notebook from scratch is to get the Rasp Pi module up and running with a fresh Linux build.

Table 1

Parts List

Part

Source

Sourced Online

JeVois smart vision camera:

http://jevois.org/

Raspberry Pi 4 (4GB model)

https://www.adafruit.com/product/4296

Logitech K400r wireless keyboard/mousepad

https://www.logitech.com/en-us/product/wireless-touch-keyboard-k400r

Samsung EVO+ 32GB micro-SD card

https://www.bestbuy.com/site/samsung-evo-plus-32gb-microsdhc-uhs-i-memory-card/5785401.p

10.1-inch color LCD screen with HDMI driver board and controls

https://www.banggood.com/10_1-Inch-1280x800-HD-Display-TFT-LCD-Module-Kit-For-Raspberry-Pi-p-1109750.html

10W per channel audio amplifier board

https://www.banggood.com/12V-Mini-Hi-Fi-PAM8610-2X10W-Audio-Stereo-Amplifier-Board-Dual-Channel-p-933675.html

15,000mAh super polymer lithium ion battery

https://www.banggood.com/DC-12V-15000mAh-Super-Rechargeable-Protable-Lithium-ion-Battery-Pack-p-970196.html

5MP Raspberry Pi camera with 12-inch flat cable

https://www.amazon.com/Raspberry-Camera-Module-Megapixels-Sensor/dp/B07L82XBNM/ref=sxin_7_ac_d_pm

HDMI to micro-HDMI adapter

https://www.banggood.com/1_5M-Micro-HDMI-Male-D-Type-to-HDMI-Female-A-Type-Adapter-Support-3D-HD-1080P-V1_4-For-FPV-Goggles-p-1098351.html

Micro-HDMI to HDMI adapter

https://www.banggood.com/Micro-HDMI-D-Type-Male-to-HDMI-A-Type-Female-Adapter-Connector-Cable-p-1143811.html

12V to xV regulator (x2)

https://www.amazon.com/Regulator-DROK-Converter-Step-Down-Transformer/dp/B0758ZTS61/ref=sr_1_12

Locally Sourced

Short audio aux cable

12V, 1A wall wart

Miniature 8-ohm speaker (x2)

Latch spring (x2)

Various brass and steel #8 machine screws, nuts, and washers

1/4-inch threaded rod, 5 inches long (x2)

1/2-inch copper tubing

1/2-inch copper elbows

3/16-inch brass tubing

1/4x1/8-inch flat brass

Unlike the old days, Linux system installation on a Pi is very straightforward. Basically, I performed a stock Raspberry Pi OS build. First, I downloaded the latest Raspberry Pi OS [2] (formerly Raspbian Linux). At the time of the project, this was 2020-05-27-raspio-buster-armhf.zip. Next, I unzipped the package on my ASUS Linux notebook daily driver and used the dd command to make short work of writing the ISO image to a Samsung EVO+ 32GB microSD card, which I then popped into the Rasp Pi before powering up the board. Lastly, I ran through the resize the main partition menu and set up wireless access with my local router SSID. I enabled SSH and changed the memory split to 256MB for optimal video performance. SSH is useful for copying code and working files from my ASUS notebook to the lunchbox Pi.

The Tube Frame

With the Rasp Pi operating system squared away, I will look at the physical hardware side next, but before I get into the details of the tube frame, let me explain why I chose a lunchbox layout.

I like a full-sized keyboard and wanted to use the very common Logitech K400r wireless keyboard/mousepad. The dimensions are 14x5.5x1 inches (WxHxD). The keyboard size pretty much drove the frame design because I also wanted to use it as a front cover for the 10.1-inch color LCD screen during transport (Figure 3) or when the machine was not in use.

Figure 3: Lunchbox with the keyboard cover latched on the front.

The tube frame provides a rugged, yet fairly light foundation for mounting the rest of the hardware. It consists of 1/2-inch straight copper tubing sourced from a big-box home improvement store. The tubing comes in 8-foot lengths, so I cut it with a standard plumber's tubing cutter. Corners are 1/2-inch copper elbows. The front and rear rectangular frames are separated by 1/4-inch threaded rods. Copper is pretty easy to solder and machine. I used a regular propane torch and rosin-core solder to fix the tubing to the elbows (Figure 4). A drill press aided in placing accurate holes for the various mounting points in the tubing and elbows. The case ended up measuring 14.5x8x5 inches (WxHxD).

Figure 4: Frame copper elbow corner detail.

The Rasp Pi configuration of video output and power ports at the bottom and the USB ports at the back established the depth of the lunchbox. To make the lunchbox thinner, I could have turned the Pi so the USB ports were facing the left-hand side of the case. I might try that on the next major iteration.

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