Maker Aaron Christophel has revealed a instrument for taking full management over the low-cost passive Close to Discipline Communication (NFC)-driven ePaper shows accessible from embedded {hardware} specialist Waveshare — reverse-engineering the undocumented system-on-chip inside.
“Waveshare offers an instance app and likewise an SDK [Software Development Kit] to construct your individual Android app the place you’ll be able to simply place your cellular system or any NFC system onto the show and it’ll refresh it,” Christophel explains of the units. “Whereas Waveshare is kind of open about what’s the option to drive them, they don’t actually disclose any information on what half is inside.”
Seeking to take extra direct management over the units — which provide a wire-free option to replace the displayed picture, harvesting sufficient vitality from an NFC transmitter to replace the electrophoretic ePaper show — Christophel set about determining what was happening inside. That, it turned out, was a Chivotech TN2115S2 system-on-chip, for which a datasheet exists with sufficient info to get began.
Dumping the content material of the chip, Christophel turned to the Ghidra disassembler to reverse-engineer the capabilities required for driving the show. With that, the maker was in a position to create his personal customized firmware — loadable utilizing a Segger J-Flash Lite set to an Arm Cortex-M0 goal.
That is, in fact, removed from Christophel’s first time experimenting with ePaper tags. Three years in the past he demonstrated an Espressif ESP32-based instrument which served to regulate widespread digital shelf label (ESL) ePaper shows, adopted by a option to flash ones constructed round Texas Devices’ CC8051. He is additionally recognized for placing them to make use of in tasks starting from low-power desk clocks to person-scale wall-art.
Christophel has launched supply code and a precompiled binary for the challenge on GitHub below the reciprocal GNU Basic Public License 3, to accompany the video embedded above.
