Low-power Kindle dashboard

Turns out old Kindle devices make great, energy efficient dashboards :-)

What this repo is

This repo only contains the code that runs on the Kindle. It periodically fetches an image to be displayed on the screen and suspends the device to RAM (which is very power efficient) until the next screen update.

This code does not render the dashboard itself. It's expected that what to display on the screen is rendered elsewhere and can be fetchd via HTTP(s). This is both more power efficient and allows you to use any tool you like to produce the dashboard image.

In my case I use a dashbling dashboard that I render into a PNG screenshot on a server.

Prerequisites

• A jailbroken Kindle, with Wi-Fi configured.
• Tested only on a Kindle 4 NT. Should work on other Kindle devices as well with minor modifications.

Installation

1. Download the latest release on your computer and extract it.
2. Modify dist/local/fetch-dashboard.sh and optionally dist/local/env.sh.
3. Copy dist/ to Kindle, for example: rsync -vr ./dist kindle:/mnt/us/dashboard.
4. Start dashboard with /mnt/us/dashboard/start.sh.
   Note that the device will go into suspend about 10-15 seconds after you start the dashboard.

How this works

• This code periodically downloads a dashboard image from an HTTP(s) endpoint.
• The interval can be configured in dist/local/env.sh using a cron expression.
• During the update intervals the device is suspended to RAM to save power.

Notes

• The releases contain a pre-compiled binary of the ht command-line HTTP client. This fully supports modern HTTPS crypto, wheras the built-in curl and wget commands don't (because they rely on a very old openssl library).

Credits

Thanks to davidhampgonsalves/life-dashboard for the inspiration!