Digital Holga

The holga-pi is a raspberry pi based digital holga. It snaps pictures and uploads them via wifi. Also includes a simple webapp to display images in realtime.

Hardware

Parts

• Raspberry Pi Camera Board v2
• Raspberry Pi Zero
• Raspberry Pi Zero v1.3 Camera Cable
• Pisugar battery pack
• MicroSDHC card, some cables, a LED
• Flash-Bang SW602

Wiring

I connected the pi to the original camera shutter, which works fine. My LED is placed in the viewfinder. The flash is mounted in the original position and wired up to the light sensitivity switch above the lens. The flash is powered by a separate battery to not drain the one of the pi.

• Camera shutter
  • Pin 7 - GPIO https://pinout.xyz/pinout/pin7_gpio4#
  • Pin 1 - 3.3v https://pinout.xyz/pinout/pin1_3v3_power#
  • Ground https://pinout.xyz/pinout/ground#
• Status LED
  • Pin 17 - 3.3v https://pinout.xyz/pinout/pin17_3v3_power#
  • Pin 10 - https://pinout.xyz/pinout/pin10_gpio15#
• Flash
  • Pin 12 - PWM https://pinout.xyz/pinout/pin12_gpio18#
  • 5v / Ground

For inspiration, check the images folder.

Setup

Raspberry Pi

• Install Raspbian (stretch)
• Install node on pi zero with https://github.com/sdesalas/node-pi-zero
• Enable ssh https://www.raspberrypi.org/documentation/remote-access/ssh/
• Upload public key ssh-copy-id pi@raspberrypi.local
• Login ssh pi@raspberrypi.local
• Change default password https://www.raspberrypi.org/documentation/linux/usage/users.md
• Enable the camera in sudo raspi-config under Interfacing Options
• Configure /boot/config.txt: start_x=1 gpu_mem=128
• Change hostname (optional https://www.howtogeek.com/167195/how-to-change-your-raspberry-pi-or-other-linux-devices-hostname/

Camera script

git clone https://github.com/masone/holga-pi.git
cd ~/holga-pi/camera
sudo npm install --unsafe-perm epoll

To start the process manually:

CLOUDINARY_URL=cloudinary://... sudo -E node index.js

Logs can be found in tail -f ~/holga-pi.log

The gpio library requires you to run the process with sudo rights.

Start on reboot

Install https://github.com/resin-io/resin-wifi-connect to create a hotspot creation when network is unavailable. Once the pi has wifi, it will start the camera.

Firstly, configure your CLOUDINARY_URL in holga-pi.service, then:

sudo cp ~/holga-pi/camera/holga-pi.service /etc/systemd/system/holga-pi.service
sudo systemctl enable /etc/systemd/system/holga-pi.service

The gpio library and wifi-connect require you to run the process with root.

Webapp

The camera uploads images to cloudinary, which can be displayed on the web.

git clone https://github.com/masone/holga-pi.git
cd ~/holga-pi/ui
npm install
node index.js

For available image filters, see https://cloudinary.com/documentation/image_transformations

LED Behavior

• Solid: Ready
• Fast blink: Processing or uploading a snapshoat
• Slow blink: Snapping or uploading failed

Notes to self

• Library for the switch https://www.npmjs.com/package/onoff
• Library for the camera https://github.com/troyth/node-raspicam
• Image upload / storage https://cloudinary.com/documentation/image_upload_api_reference
• Image api https://cloudinary.com/documentation/admin_api#browse_resources
• Update firmware sudo rpi-update
• Update raspbian: sudo apt-get update sudo apt-get dist-upgrade
• Test camera with vcgencmd get_camera
• Troubleshooting camera module https://elinux.org/Rpi_Camera_Module#Troubleshooting
• Save power https://monkeyinmysoup.gitbooks.io/raspberry-pi/content/5.1-power-consumption.html, underclock sudo vim /boot/config.txt: arm_freq, disable HDMI /usr/bin/tvservice -o
• sudo -E node ... is required to pass on the environment variables to the sudo command (CLOUDINARY_URL)
• Check status systemctl status holga-pi