Porta-Pi - A portable large-screen Pi Zero 2 W rig

Description

This project is the combination of two desires. Years ago I designed a Pi Zero expansion board called the Solar Pi Platter and ran a kickstarter. It provides 3 USB ports, LiPo power/charging and other features. I still have some boards left for sale and I wanted to see if they'd work with the new(ish) Pi Zero 2 W board. The Pi Platter uses 4 pogo pins to connect power and USB to test pads on the bottom of the Pi Zero. I was pleasantly surprised that the Pi Zero 2 W board had the same test pads and worked perfectly.

I had also been playing with the official Raspberry Pi 7" touchscreen and found the low 800x600 pixel resolution to be less than ideal. Some searching revealed a Norsmic 7" 1024x600 pixel HDMI monitor with a built-in USB cap touchscreen, mount points and built in speakers.

I decided to combine the Pi Platter and monitor into a portable computer called Porta-Pi because it's cool and maybe will entice a few people to buy Pi Platters so I can get ri

Files

mount_plate.zip

OpenSCAD (and STL) 3D printed mount plate design

Zip Archive - 49.51 kB - 10/18/2022 at 02:30

Download

Components

1 × Raspberry Pi Zero 2 W Single Board Computer

1 × Solar Pi Platter Expansion board

1 × Norsmic 7" 1024x600 pixel touchscreen HDMI monitor

1 × 4400 mA Li-Ion 3.7V battery

1 × 5.25V 3A USB Adapter

Build Instructions

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1

Gather parts / notes about parts

I bought my monitor from Amazon. As I write this it can currently be found at this link. If that link rots then you can search for for "Raspberry Pi Screen,NORSMIC 7 inch Monitor, IPS HD 1024×600, Responsive Capacitive Touch". Here's a picture showing the parts that came with my monitor. You'll be using a couple of them.

The included Power Adapter will work but due to typical voltage drops in USB cables which will reduce the charge current, you should use a USB Micro-B adapter that puts out 5.1 or 5.25 volts at 3 A. The official Raspberry Pi adapter works well.

The Pi Platter can provide up to 750 mA charge current for the attached 3.7V LiPo battery. This is a good match for a matched dual-18650 4400 mA pack. I got mine from Adafruit. Be sure it has the Sparkfun/Adafruit JST pinout.

Get the smallest HDMI to HDMI mini adapter you can find. I had an old one that I bought when the first Pi Zero came out but it appears other models are equally as small.

You'll also need a Raspberry Pi Zero 2 W (or Raspberry Pi Zero W) and a micro SD Card for the Raspberry Pi OS, a Pi Platter, some zip-ties and the ability to 3D print (or otherwise fashion) a simple mounting plate which is described in the next step.
2

Mount Plate

A simple mount plate is used to hold the battery pack. It has holes spaced for the Raspberry Pi mount points on the monitor PCB, holes for the Pi Platter and zip tie cut-outs for the battery. The design is in OpenSCAD and that file, and the generated STL are included in the "mount_plat.zip" file included in this project.

If you don't have access to a 3D printer you can convert the design for a laser cutter or even drill a very sturdy piece of cardboard with the dimensions (mm) in the OpenSCAD source file.

Add a set of four 0.25" M3 standoffs with nuts and zip ties for the battery. The zip ties should be loose enough for the battery to be installed. They can be tightened then.
3
Prepare the monitor
The monitor comes with a bunch of useful cables. The build uses 2 of them.
1. HDMI plug with flex cable
2. USB Type A plug with wire harness to 4-pin connector
The USB Type A to USB Micro-B can also be used with a power adapter to power/charge the system.

Connect the flex and USB cables as shown below. The flex cable has double sticky tape on one side. I also used another piece of tape to make sure the connection was secure.

Attach the mount plate to the Raspberry Pi standoffs on the monitor using screws supplied with the monitor.