Golang-Powered Calendar HMI on Raspberry Pi Zero 2 W with ePaper

This project uses a Raspberry Pi Zero 2 W and a Waveshare 12.48-inch ePaper display as a basic HMI (Human-Machine Interface). It runs on a Boot2Qt Yocto extension project. The calendar you see is from a Go (Golang) app that gets its content using a calendar ID from a config file.

ps. you still can use other rpi 3/4/5 ... and raspberrypi os

ps. the reference data for waveshre epaper is here https://www.waveshare.net/wiki/12.48inch_e-Paper_Module_(B)

Environment

please use the linux system, the golang application might run on the windows system, but most of actions need use linux commands such as mount, ln, ...., these commands/utilities are not supported on windows system.

download the source code

git clone https://github.com/fusigi0930/rpi_epaper rpi_epaper

Prepare the raspberry pi system

please follow the QT official document https://doc.qt.io/Boot2Qt/b2qt-how-to-create-b2qt-image.html, build a b2qt system first, in this case please use the manifest file v6.9.1.xml (the machine is raspberrypi-armv8), after finish building process, please use the shell script to do some post action, that reduce some unnecessary system service and follow the steps from waveshare epaper to close the spi device tree and install the libraries for lg into the system

cd rpi_epaper/system
./setup_zero2w.sh /dev/xxxxx

Prepare the host environment

please download the golang (1.24.x) from the official website https://go.dev/doc/install and install

donwlaod the sdl2 development libraries

• linux system

sudo apt update
sudo apt install libsdl2-dev libsdl2-image-dev libsdl2-ttf-dev libsdl2-mixer-dev

• windows system download the sdl2 from the url: mingw: https://github.com/libsdl-org/SDL/releases/download/release-2.32.8/SDL2-devel-2.32.8-mingw.zip vc: https://github.com/libsdl-org/SDL/releases/download/release-2.32.8/SDL2-devel-2.32.8-VC.zip

Calendar go project

the calendar is implemented by using golang, and it support a windows/linux virtual window to simulate the screen on the e-paper, that means you can build on the windows/linux system and do some UI adjustment, then cross build the raspberrypi version on the linux system.

Environment

• go language 1.24 and laters
• cmake 3.16 and laters
• gcc, make utilities, ...(if the windows system, the mingw-w64 is necessary)
• ninja (for windows only, that avoids the cmake to use visual studio)

the urls for windows: golang: https://go.dev/doc/install cmake: https://cmake.org/download/ gcc: https://www.msys2.org/

on ubuntu linux, you can directly get the package by the commands

sudo apt update
sudo apt install cmake gcc g++ gcc-multilib g++-multilib make

Create Google Cloud Console key

1. we need to create a Google service account to access a specific Google Calendar (usually your own). Therefore, you should create the service account by following the steps provided at https://cloud.google.com/iam/docs/service-accounts-create.
2. open your google calendar on the browser and add the service account to the "Share"
3. create and export the key from the account service and store the json to the path

• windows: %ProgramData%\ggcal\
• linux/rpi: /etc/ggcal/

4. create a config yaml file on the same path with the name "calconfig.yaml", and update the filename for the key on the document. e.g.

cred_file: "xxxxx_service.json"
holiday_cal: "zh.taiwan#holiday@group.v.calendar.google.com"
calendar:
 - "your_google_calendar_id@gmail.com"

layout definition file

in the source code, a default layout file "layout.yaml" it should be copied to the path after run the script setup_zero2w.sh, you can adjust some configuration from it in need.

• windows: %ProgramData%\ggcal\
• linux/rpi: /etc/ggcal/

Fonts

download the free TTF font from google (https://fonts.google.com/noto/specimen/Noto+Sans+TC), copy the font files to the path you want after decompress it. the path is up to you, and don't forget modify the fontpath in the layout.yaml file

fontpath: "..."