A fork of the CrossPoint firmware by Nishant Joshi turns ESP32-C3-based Xteink X4 and X3 e-ink readers into network printers. The firmware implements IPP, the Internet Printing Protocol, directly on the microcontroller. Your OS sees it as a monochrome, single-sided printer advertising 300 DPI output on A5 paper, accepting Apple raster and PWG raster formats. You select it, you press print, it works.
The hard constraint is RAM. Raster images are large, the ESP32-C3 is not. Joshi's solution is row-by-row processing: pixels arrive, pixels write to screen, pixels write to SD card simultaneously. The SD card becomes the output tray. The approach is not elegant in the traditional sense but it is disciplined engineering under a real constraint, and the full write-up details exactly how that pipeline is managed.
The deeper point is longevity. IPP is a mature, OS-level standard baked into Windows, macOS, and Linux. As long as those operating systems exist, this device has a supported input method requiring zero drivers and zero apps. That architectural decision, not the e-ink novelty, is what makes the full article worth reading.
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