E-Paper Calendar Ep.1 - Kicking Off The Project

This article is migrated from Medium and translated by Gemini pro 2.5.

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I’ve decided to start a new project: building a physical Google Calendar display using an e-paper screen.

Why a Physical Google Calendar?

You might be wondering why anyone would need this. For me, it comes down to a few key points:

1. E-Paper is Easy on the Eyes: E-paper screens don’t emit their own light; they rely on ambient light, just like real paper. This makes them incredibly comfortable to look at.
2. Ultra-Low Power: E-paper only consumes power when the image is changing. A static display uses zero energy.
3. Passive Reminders: A calendar is meant to be a constant reminder of your schedule. It should be placed somewhere you can see it often. If I have to pull out my phone just to check my schedule, the calendar has already failed its primary purpose.

The Initial (Failed) Shortcut

When I first started gathering info, I found a crowdfunding project on ZecZec for a very similar product. The price was even lower than my own estimated bill of materials (BOM), so I decisively gave up on the DIY plan and just placed an order.

However, even before I received the product, I saw early backers reporting a terrible user experience. I already knew the screen refresh would be slow—e-paper isn’t designed for high-frequency updates. But then I saw someone say you had to pull out your phone to force the screen to update.

Doesn’t that defeat the entire purpose of the product?

I got a refund and went back to the drawing board. It was time to build it myself.

After some research, I found a couple of projects that served as great inspiration:

• SpeedyG0nz’s MagInkCal (Raspberry Pi)
• An E-Ink Family Calendar Using ESP32 on Instructables

Defining the Project Goals

First, I need to set clear goals so I can review them later.

• The device must be able to connect to Google Calendar on its own to fetch the latest event data. A once-daily update should be sufficient. The main goal is to see future plans; last-minute additions aren’t the focus here.
• It can be either a desktop or wall-mounted device. I’ll figure this out at the end, as it relates to whether I’ll use battery power or a wired adapter.

The most critical component is the e-paper screen. I saw the first reference project used a Waveshare dual-color screen with good results. I’ve used their 7” touch screen before for a custom car navigation project, and the quality was decent. Plus, they offer a wide variety of options and resources.

A calendar needs to display a lot of information, so the screen size should be 7 inches or larger to be comfortable to read. Considering this is my first time using an e-paper display and the project could fail, I decided not to buy a massive 12” screen just yet.

I settled on a 7.5” four-color (Black, White, Yellow, Red) e-paper display. The price was more acceptable, and at this size, I might have to consider a “daily” calendar format, as a “monthly” view might be too cluttered to read.

Identifying Potential Bottlenecks

Next, I listed out the challenges I can anticipate:

1. Driving the E-Paper Display: This shouldn’t be a huge problem, but since I’ve never used one, I don’t know how deep the water is.
2. Fetching Google Calendar Data: There should be plenty of resources online for this.
3. Efficient Display Rendering: I’m thinking I’ll need to divide the screen into several “regions” to manage and update them efficiently.
4. Displaying Mandarin Characters: This is the biggest bottleneck I can think of right now, and it has the potential to kill the entire project.

…Unfortunately, I only thought of this after I had already bought the screen. Oh well, I’m already in too deep.

I’ll wait for the screen to arrive and start experimenting. I’ll post the next update then.