24. June 2022

Weather display for LilyGO TTGO T5-4.7″ E-Paper ESP32 deployed using Arduino IDE 2.0

LilyGO TTGO T5-4.7″ E-Paper ESP32 is nice display which integrates ESP32, USB-C, Li-Po and 18650 accumulator support in one board. The display driver is GDEH0213B72.

One interesting use-case for the board is the Weather display.

There are several steps to get the Weather display working. Let’s walk through them.

Drivers

Linux users may skip this section since the modern kernel supports CH34x drivers.

macOS users may encounter the following error when flashing:

Failed to write to target RAM (result was ...)

It’s necessary to install the driver from https://github.com/WCHSoftGroup/ch34xser_macos.

Windows 8, 10 users may need to install https://www.wch.cn/download/CH343SER_EXE.html. Windows 11 should install the driver automatically.

Arduino IDE setup

Download Arduino IDE 2.0.

Add ESP32 boards support. Click File, click Preferences, select Settings tab. Enter the following URL to Additional boards manager URLs:

https://raw.githubusercontent.com/espressif/arduino-esp32/gh-pages/package_esp32_index.json

Click Ok. Click Tools, select Boards: …, click Boards Manager… . It will open the left pane with a list of boards. Type esp32 to Filter your search field. Find esp32 by Espressif Systems, click Install.

Preparing code

Open a terminal and clone LilyGo-EPD47 library to Arduino/libraries:

Linux:

cd ~/Arduino/libraries
git clone git@github.com:Xinyuan-LilyGO/LilyGo-EPD47.git --depth 1

macOS:

cd ~/Documents/Arduino/libraries
git clone git@github.com:Xinyuan-LilyGO/LilyGo-EPD47.git --depth 1

Make a clone LilyGo-EPD-4-7-OWM-Weather-Display to the directory with Arduino projects. The folder name with the project should match the name of the source code file OWM_EPD47_epaper_v2.5 to avoid the unnecessary step of moving the file.

Linux:

cd ~/Arduino
git clone git@github.com:Xinyuan-LilyGO/LilyGo-EPD-4-7-OWM-Weather-Display.git OWM_EPD47_epaper_v2.5

macOS:

cd ~/Documents/Arduino/
git clone git@github.com:Xinyuan-LilyGO/LilyGo-EPD-4-7-OWM-Weather-Display.git OWM_EPD47_epaper_v2.5

Open Arduino IDE 2.0, click File, select Sketchbook, click OWM_EPD47_epaper_v2.5.

The project requires ArduinoJson to build. Click Tools, click Manage libraries… . The pane with Library Manager should open, type ArduinoJson to Filter your search field. Find ArduinoJson by Benoit Blanchon, click Install.

Try to build the project.

It might fail with the following error:

.../Arduino/libraries/LilyGo-EPD47/src/rmt_pulse.c:9:24: fatal error: hal/rmt_ll.h: No such file or directory
compilation terminated.
Multiple libraries were found for "WiFiClient.h"
  Used: .../.arduino15/packages/esp32/hardware/esp32/1.0.4/libraries/WiFi
  Not used: .../arduino-1.8.13/libraries/WiFi
exit status 1

Open the file ~/Arduino/libraries/LilyGo-EPD47/src/rmt_pulse.c and comment out line 9:

/* #include <hal/rmt_ll.h> */

The project should be buildable now.

Configuring local parameters

Open file owm_credentials.h and configure ssid, password, apikey, City, Country.

The project is acquiring data from openweathermap.org. Create new free account in order to get apikey.

The project implementations contain support for power saving, so if you’re flashing in the early morning/late night, you might be surprised that nothing is on display. To change power-saving options open file OWM_EPD47_epaper_v2.5.ino and change WakeupHour to a value that suits your need.

Flashing

Connect the module. Select the board from the dropdown in the toolbar. Click Port (/dev/ttyACMx on Linux), filter for ESP32 Wrover module and click Ok.

Click the Upload arrow.

If the flashing is successful, you may enjoy the new Weather display. Congratulations!

3D printed enclosure

There are several versions of files for 3D printing. You can find them in the discussion at GitHub – LilyGo-EPD47. The picture in this article is based on model thing:4782302 printed on Original Prusa MINI+ with PET-G. The model has a few cosmetic limitations:

  • It’s not possible to keep the display standing while USB-C is connected.
  • Buttons are not completely reachable.
  • The display must be attached by a tape or other method to the stand to avoid detaching from the case.

Notes

Double-check whether the battery holder is present when ordering the board with the display from the e-shop. Even when it’s displayed on the picture, it does not mean that the battery holder or battery is part of the delivery.

When connecting by USB-C to USB-C cable, the device should light up at least a red led. If nothing is visible, rotate the USB-C connected to the board by 180 degrees or use USB-A to USB-C cable.

3. May 2022

Podman Debian apt-get update fails with “InRelease is not valid yet”

Podman 4.0.3 users on macOS might face the following strange error when building an image:

apt-get update
...
E: Release file for http://security.debian.org/debian-security/dists/bullseye-security/InRelease is not valid yet (invalid for another 3h 1min 9s). Updates for this repository will not be applied.
E: Release file for http://deb.debian.org/debian/dists/bullseye-updates/InRelease is not valid yet (invalid for another 7h 24min 41s). Updates for this repository will not be applied.

The problem is caused by the not synced clock in Podman VM. This might happen due to the hibernation of the notebook.

The quick fix of the problem is to restart Podman’s VM:

podman machine stop
podman machine start

2. April 2022

ESP32 Arduino macOS exec: “python”: executable file not found in $PATH

Apple removed old Python 2 from macOS 12.3. Arduino ESP32 depends on Python interpreter.

Build in Arduino IDE may fail with error:

"python": executable file not found in $PATH

It’s sufficient to change name of binary to python3

Edit file

~/Library/Arduino15/packages/esp32/hardware/esp32/2.0.2/platform.txt

Change the line:

tools.gen_esp32part.cmd=python "{runtime.platform.path}/tools/gen_esp32part.py"

To line with python3:

tools.gen_esp32part.cmd=python3 "{runtime.platform.path}/tools/gen_esp32part.py"

Re-open Arduino IDE and build the project.

1. April 2022

How to develop for ESP32-C3 with Rust on macOS with Lima using Dev Container in VS Code

Lima is a solution for macOS for managing Linux VM on macOS which plays well with Dev Containers. It has several advantages over Docker Desktop for macOS or Podman.

Let’s see how it can be used for the development of software for embedded hardware like ESP32-C3 using source code from Ferrous Systems training:

git clone https://github.com/ferrous-systems/espressif-trainings.git

Install Lima and Docker-CLI:

brew install lima docker

Create Linux VM with Dockerd (following instructions from Kevin O’Brien – Utilizing Docker CLI without Docker Desktop):

curl https://raw.githubusercontent.com/lima-vm/lima/master/examples/docker.yaml -O
limactl start ./docker.yaml
limactl shell docker
sudo systemctl enable ssh.service

There is one important tweak in the Lima configuration. It’s necessary to enable write operation otherwise, the workspace mounted from VS Code is read-only. Open file ~/.lima/docker/lima.yaml and add writable flag to desired folder:

mounts:
- location: "~"
  writable: true

Restart Lima to apply changes.

limactl stop docker
limactl start docker

Create context for Docker-CLI to connect to dockerd running in the VM:

docker context create lima --docker "host=unix://${HOME}/.lima/docker/sock/docker.sock"
docker context use lima

Open VS Code with the installed Remote Container plugin and click Re-Open in Container:

cd espressif-trainings
code .

Open terminal in VS Code and build the example:

cd intro/hardware-check
cp cfg.toml.example cfg.toml
cargo build

Flashing of the resulting file could be done by espflash and mounting the device to Lima or using a tool like Adafruit WebSerial ESPTool. The file for flashing is located in the directory target/release.

31. March 2022

How to develop for ESP32-C3 with Rust on macOS with Podman using Dev Container in VS Code

Development in Dev Containers using VS Code greatly simplifies bootstrapping of the development environment. The developer does not need to install toolchains locally and spends a lot of time composing the development environment.

The default installation of VS Code is configured to work with Docker. It requires some small additional steps to switch to Podman.

Let’s begin with development using examples from Ferrous Systems training:

git clone https://github.com/ferrous-systems/espressif-trainings.git

Install Podman and check version:

brew install podman
podman --version

The version should be at least 4.0. If you have a previous version, consider an upgrade.

Following step might not be obvious to Docker users. Docker creates VM for managing containers in the background without asking the user. In the case of Podman, this is more versatile and you can define what kind of machine do you want to create. Here are a few options recommended for development, when you omit them you’ll get smaller defaults.

podman machine init --disk-size 20 --cpus 8 -m 4096 -v ${HOME}/espressif-trainings:${HOME}/espressif-trainings
podman machine start

Please, notice also -v option which mounts the development directory to Podman VM, without this mount you’ll get:

Error: statfs espressif-trainings: no such file or directory

Now the Podman VM should be ready and we can spin up containers. Go to the project directory and open Visual Studio Code:

cd ${HOME}/espressif-trainings
code .

It’s necessary to install one additional dependency for Podman: podman-compose

pip3 install podman-compose

It’s necessary to tell VS Code to use podman instead of docker commands. Go into Settings and search for keyword docker. Replace docker by podman and docker-compose by podman-compose.

VS Code is ready and click Reopen in Container.

Pulling the base image might take a while.

Open terminal and build the first ESP32-C3 example:

cd intro/hardware-check
cp cfg.toml.example cfg.toml
cargo build

Note: If VS Code is complaining about existing vscode volume, it’s possible to remove it by command

podman volume rm vscode

Note 2: If the remove is blocked by the existing terminated container, it’s possible to clean the reference by command

podman container prune

Flashing of the resulting file could be done by espflash and mounting device to Podman or using the tool like Adafruit WebSerial ESPTool. The file for flashing is located in the directory target/release.