# Inkpot on ESP32 Lilygo T5

This repository contains the sources required to run the Inkpot frontend on a Lilygo T5, an ESP32 equipped with an e-ink display. It allows you to create Lua sketches that draw on the e-ink screen.

You need to give it a 2.4Ghz Wifi SSID and password by adjusting `main/settings.h`. After that it will start an HTTP server that you can use to interact with the device. The HTTP server has two endpoints:

- `GET /` -- Hello world page to confirm that things are working
- `POST /draw` -- Accepts a Lua POST body and will execute the script

You can send scripts like this:

``` bash
cat assets/post_test.lua | curl -X POST --data-binary @- 10.0.0.100/draw
```

The IP address of the display is logged to its serial output and can be read via `idf.py monitor` (see below).

## Prerequisites

There is a `flake.nix` at the root of this repository that defines a development environment with all required tools. If you are using `direnv`, `cd` into the repositorie's root directory after cloning it and run `direnv allow`. If you aren't using direnv the enviroment can be activated using `nix develop .`.

The build environment consists of:

- ESP-IDF version 5.1.0 or higher
- Components:
  - [Lua 5.4](https://components.espressif.com/components/georgik/lua/)
  - [LittleFS 1.14](https://components.espressif.com/components/joltwallet/littlefs/)
  - [EPDIY](https://github.com/vroland/epdiy)

## Build and Flash

```bash
idf.py set-target esp32
idf.py build flash monitor
```

You can stop the monitor by pressing `Ctrl + ]`.

## File Structure

- `main/`
  - `inkpot.c`: Main program containing embedded Lua script and file-based Lua execution.
  - `paper.c`: Defines the lua bindings to epdiy that can be used for drawing on the screen.
- `assets/`: Directory containing all Lua scripts; some are older example scripts that are not executed
  - `boot.lua` contains the sketch that runs at startup
  - `post_test.lua` contains another sketch