This project tries to mimic the 90s solar digital watches that run forever.

But with newer technology (eInk/WiFi/BT/Lora/GPS, ...).

The challenging part of this project is to minimize the ESP32 on time to sub "ms" levels while updating the display. This was done with re implementation of SPI in the wake stub code of the ESP32.

The requirement for a feature to be added in is that it can be power gated and off when not needed, and overall does not use much power (and fits in the space!).

The project name comes from Light-weight - Light powered eInk.

tech

![](https://cdn.hackaday.io/images/2610231776970431758.jpg)

> This project tries to mimic the 90s solar digital watches that run forever.
> But with newer technology (eInk/WiFi/BT/Lora/GPS, ...).
>
> The challenging part of this project is to minimize the ESP32 on time to sub "ms" levels while updating the display. This was done with re implementation of SPI in the wake stub code of the ESP32.
>
> The requirement for a feature to be added in is that it can be power gated and off when not needed, and overall does not use much power (and fits in the space!).
>
> The project name comes from Light-weight - Light powered eInk.

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Hackaday.io project page: [https://hackaday.io/project/205564-lightink](https://hackaday.io/project/205564-lightink)

Youtube channel: [https://www.youtube.com/channel/UC85IYb1iQYl5axvtkAJRysg](https://www.youtube.com/channel/UC85IYb1iQYl5axvtkAJRysg)

***

https://www.youtube.com/watch?v=qBj7sOVVzNI