Give Your Xteink X4 a Firmware Makeover

E-readers, with their eye-friendly E Ink displays, make it easy to carry an entire library in a compact, lightweight form. Still, they’re one more device to remember, and often get left behind when the opportunity to read arises. While phones don’t provide the same comfortable reading experience, they’re always close at hand, making them the go-to choice for squeezing in quick reading sessions throughout the day.

Fortunately, that trade-off is disappearing, thanks to devices like the Xteink X4. It is a device that effectively turns your phone into an e-reader by attaching to its back. It features a 4.3-inch E Ink display with a resolution of 220 PPI and weighs only 74 grams. Powered by an ESP32 microcontroller, it stores books on microSD cards. The X4 connects magnetically to your phone, and for devices without built-in magnets, it includes adhesive magnetic rings.

Concretedog picked up an X4 a while back and fell in love with the hardware — but not the firmware. As Concretedog found out, however, there is a thriving open source community writing software for the X4, so you aren’t stuck with what Xteink provides. And best of all, it’s really easy to flash new firmware. You won’t need to open the case, solder wires to pads, or even buy a specialized programmer.

Using a Chromium-based browser, users can install alternative firmware like Crosspoint Reader with just a few clicks. This dramatically improves usability over the stock firmware, which has been criticized for limited features and default Chinese localization.

Once updated, the X4 becomes a flexible EPUB reader with multiple ways to load content. The most straightforward approach is copying files directly to a microSD card. However, Crosspoint Reader also enables wireless transfers: the device can act as a Wi-Fi hotspot with a built-in file browser, or connect to an existing network for remote access from another device.

The update also provides many options for content creation. A browser extension allows users to capture long-form web articles and convert them into EPUB files for offline reading. Meanwhile, productivity tools like LibreOffice Writer can export documents directly into EPUB format, making it easy to review drafts or carry notes on the go.

Additional features, like customizable sleep screen images, add a layer of personalization. Some users have even repurposed the display as a wearable badge. If you would like to get more out of your X4, be sure to check out Concretedog’s project write-up for all the details you’ll need.