half-duplex/pimera

A Raspberry Pi USB Gadget Toolkit

PiMera

Like chimera. Get it?

PiMera allows your Pi Zero W to do a variety of handy things, with a shiny UI. It can act as:

• CD drive or flash drive: Present any image you choose. No more having to dd a new iso to your flash drive every other day. Read-only or read-write for flash drive images.

Future ideas:

• USB network card: SSH to the Pi, or use it as a mediocre wifi adapter!
• Serial interface: For easy management

Hardware

• A Linux board that supports USB gadgets and a compatible display
  • Raspberry Pi Zero W with headers, ~US$11-14
  • Raspberry Pi Zero with headers, ~US$6-9 but more setup effort
  • NOT supported: Raspberry Pi Model A/B do not support the gadget system
• A MicroUSB cable or a USB A stem
• Interface
  • Waveshare 1.3in OLED Hat, about US$17
  • Similar displays may be easy to support, pull requests welcome!
• A MicroSD card of at least 8GB. 2-4GB will be used for the system. A higher quality card will be a better experience, both in speed and longevity.

Setup

1. Download Raspberry Pi OS Lite (unless you're doing other stuff) and flash it to the SD card normally
2. Either create a new partition starting at ~4GiB (sudo parted /dev/sdX mkpart p 4GiB 100%) or flash tools/partition-table.img
3. In the boot partition, in config.txt, change:
   • Find #dtparam=spi=on and remove the #
   • Add a line dtoverlay=dwc2 to the end of the file
4. Optionally, for ease of access:
   • Enable SSHd: Create an empty file named ssh on the boot partition
   • Configure WiFi:

     wpa_passphrase HomeWiFi | \
         sudo tee --append rootfs/etc/wpa_supplicant/wpa_supplicant.conf

5. Boot the Pi and install the dependencies:

   sudo apt update && sudo apt install -y python3-spidev python3-rpi.gpio \
       python3-pil

6. Other things

Use

Remember to connect the Pi using the "USB" (data) port, not the "PWR" (power only) port!

With the Waveshare OLED Hat, up and down change menu items, left goes back, right selects.

When using a writable mode, please be sure to unmount the filesystem before unplugging it to minimize chances of corruption.

The system partition is also configured to be mounted read-only to minimize chances of corruption. To modify the system after installation, first remount the system read-write:

sudo mount -o remount,rw /
sudo mount -o remount,rw /boot