185 lines
8.2 KiB
Markdown
185 lines
8.2 KiB
Markdown
---
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title: "Making an Email-Powered E-Paper Picture Frame"
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date: 2021-05-12T00:00:00+00:00
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draft: false
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canonical_url: https://www.viget.com/articles/making-an-email-powered-e-paper-picture-frame/
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featured: true
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---
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Over the winter, inspired by this [digital photo
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frame](http://toolsandtoys.net/aura-mason-smart-digital-picture-frame/)
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that uses email to add new photos, I built and programmed a trio of
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e-paper picture frames for my family, and I thought it'd be cool to
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walk through the process in case someone out there wants to try
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something similar.
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In short, it's a Raspberry Pi Zero connected to a roughly 5-by-7-inch
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e-paper screen, running some software I wrote in Go and living inside a
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frame I put together. This project consists of four main parts:
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1. The email-to-S3 gateway, [described in detail in a previous
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post](/elsewhere/email-photos-to-an-s3-bucket-with-aws-lambda-with-cropping-in-ruby/);
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2. The software to display the photos on the screen;
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3. Miscellaneous Raspberry Pi configuration; and
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4. The physical frame itself.
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As for materials, you'll need the following:
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- [A Raspberry Pi Zero with
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headers](https://www.waveshare.com/raspberry-pi-zero-wh.htm)
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- [An e-paper
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display](https://www.waveshare.com/7.5inch-hd-e-paper-hat.htm)
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- A micro SD card (and some way to write to it)
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- Some 1x4 lumber (I used oak)
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- [4x metal standoffs](https://www.amazon.com/gp/product/B00TX464XQ)
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- [A 6x8 piece of
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acrylic](https://www.amazon.com/gp/product/B07J4WX7BH)
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- Some wood glue to attach the boards, and some wood screws to attach
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the standoffs
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I'll get more into the woodworking tools down below.
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## The Email-to-S3 Gateway
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Like I said, [I've already documented this part pretty
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thoroughly](/elsewhere/email-photos-to-an-s3-bucket-with-aws-lambda-with-cropping-in-ruby/),
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but in short, we use an array of AWS services to set up an email address
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that fires off a Lambda function when it receives an email. The function
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extracts the attachments from the email, crops them a couple of ways
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(one for display on a webpage, the other for display on the screen), and
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uploads the results into an S3 bucket.
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## The Software
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The next task was to write the code that runs on the Pi that can update
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the display periodically. I also thought it'd be cool if it could
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expose a simple web interface on the local network to let my family
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members browse the photos and display them on the frame. When selecting
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a language, I could have gone with either Ruby or Python, the former
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since that's what I'm most familiar with, the latter because that's
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what [the code provided by
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Waveshare](https://github.com/waveshare/e-Paper/tree/master/RaspberryPi_JetsonNano/python/lib/waveshare_epd),
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the manufacturer, is written in.
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But I chose neither of those options, reader, opting instead for Go. Why
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Go, you ask?
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- **I wanted something robust.** Ideally, this code will run on these
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devices for years with no downtime. If something does go wrong, I
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won't have any way to debug the problems remotely, instead having
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to wait until the next time I'm on the same wifi network with the
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failing device. Go's explicit error checking was appealing in this
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regard.
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- **I wanted deployment to be simple.** I didn't have any appetite
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for all the configuration required to get a Python or Ruby app
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running on the Pi. The fact that I could compile my code into a
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single binary that I could `scp` onto the device and manage with
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`systemd` was compelling.
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- **I wanted a web UI**, but it wasn't the main focus. With Go, I
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could just import the built-in `net/http` to add simple web
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functionality.
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To interface with the screen, I started with [this super awesome GitHub
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project](https://github.com/gandaldf/rpi). Out of the box, it didn't
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work with my screen, I *think* because Waveshare offers a bunch of
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different screens and the specific instructions differ between them. So
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I forked it and found the specific Waveshare Python code that worked
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with my screen ([this
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one](https://github.com/waveshare/e-Paper/blob/master/RaspberryPi_JetsonNano/python/lib/waveshare_epd/epd7in5_HD.py),
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I believe), and then it was just a matter of updating the Go code to
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match the Python, which was tricky because I don't know very much about
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low-level electronics programming, but also pretty easy since the Go and
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Python are set up in pretty much the same way.
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[Here's my
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fork](https://github.com/dce/rpi/blob/master/epd7in5/epd7in5.go) --- if
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you go with the exact screen I linked to above, it *should* work, but
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there's a chance you end up having to do what I did and customizing it
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to match Waveshare's official source.
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Writing the main Go program was a lot of fun. I managed to do it all ---
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interfacing with the screen, displaying a random photo, and serving up a
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web interface --- in one (IMO) pretty clean file. [Here's the
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source](https://github.com/dce/e-paper-frame), and I've added some
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scripts to hopefully making hacking on it a bit easier.
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## Configuring the Raspberry Pi
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Setting up the Pi was pretty straightforward, though not without a lot
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of trial-and-error the first time through:
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1. Flash Raspberry Pi OS onto the SD card
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2. [Configure your wifi
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information](https://www.raspberrypi.org/documentation/configuration/wireless/wireless-cli.md)
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and [enable
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SSH](https://howchoo.com/g/ote0ywmzywj/how-to-enable-ssh-on-raspbian-without-a-screen#create-an-empty-file-called-ssh)
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3. Plug it in --- if it doesn't join your network, you probably messed
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something up in step 2
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4. SSH in (`ssh pi@<192.168.XXX.XXX>`, password `raspberry`) and put
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your public key in `.ssh`
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5. Go ahead and run a full system update
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(`sudo apt update && sudo apt upgrade -y`)
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6. Install the AWS CLI and NTP (`sudo apt-get install awscli ntp`)
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7. You'll need some AWS credentials --- if you already have a local
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`~/.aws/config`, just put that file in the same place on the Pi; if
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not, run `aws configure`
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8. Enable SPI --- run `sudo raspi-config`, then select "Interface
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Options", "SPI"
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9. Upload `frame-server-arm` from your local machine using `scp`; I
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have it living in `/home/pi/frame`
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10. Copy the [cron
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script](https://github.com/dce/e-paper-frame/blob/main/etc/random-photo)
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into `/etc/cron.hourly` and make sure it has execute permissions
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(then give it a run to pull in the initial photos)
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11. Add a line into the root user's crontab to run the script on
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startup: `@reboot /etc/cron.hourly/random-photo`
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12. Copy the [`systemd`
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service](https://github.com/dce/e-paper-frame/blob/main/etc/frame-server.service)
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into `/etc/systemd/system`, then enable and start it
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And that should be it. The photo gallery should be accessible at a local
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IP and the photo should update hourly (though not ON the hour as that's
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not how `cron.hourly` works for some reason).
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## Building the Frame
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This part is strictly optional, and there are lots of ways you can
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display your frame. I took (a lot of) inspiration from this ["DIY
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Modern Wood and Acrylic Photo
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Stand"](https://evanandkatelyn.com/2017/10/modern-wood-and-acrylic-photo-stand/)
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with just a few modifications:
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- I used just one sheet of acrylic instead of two
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- I used a couple small pieces of wood with a shallow groove to create
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a shelf for the screen to rest on
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- I used a drill press to make a 3/4" hole in the middle of the board
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to run the cable through
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- I didn't bother with the pocket holes --- wood glue is plenty
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strong
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The tools I used were: a table saw, a miter saw, a drill press, a
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regular cordless drill (**do not** try to make the larger holes in the
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acrylic with a drill press omfg), an orbital sander, and some 12"
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clamps. I'd recommend starting with some cheap pine before using nicer
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wood --- you'll probably screw something up the first time if you're
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anything like me.
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---
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This project was a lot of fun. Each part was pretty simple --- I'm
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certainly no expert at AWS, Go programming, or woodworking --- but
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combined together they make something pretty special. Thanks for
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reading, and I hope this inspires you to make something for your mom or
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someone else special to you.
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*Raspberry Pi illustration courtesy of [Jonathan
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Rutheiser](https://commons.wikimedia.org/wiki/File:Raspberry_Pi_Vector_Illustration.svg)*
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