Show HN: Hacking a $20 4G wireless hotspot into a texting device
summary
The author transforms a cheap $20 4G wireless hotspot into a dedicated handheld messaging device by integrating it with a physical keyboard and a high-contrast memory display. This project demonstrates how off-the-shelf hardware, like the MF800 modem and a Clicks keyboard, can be repurposed through custom PCB design and Linux kernel modifications. The result is a specialized, distraction-free communication tool that prioritizes utility over aesthetic perfection.
key points
- The hardware build requires a custom adapter PCB to handle USB host/device mode switching, power boosting to 5V, and signal level conversion for the display.
- Installing Linux via the OpenStick project allows for deep system control, though it requires modifying the device tree and patching the kernel driver to enable a DRM display output with dithering for better visuals.
- Physical integration involves cutting the original modem PCB to fit into a modified keyboard case, requiring manual wiring of SPI lines and careful management of USB data line interference.
who should read it
Hardware enthusiasts and embedded systems developers who enjoy repurposing electronics and working with Linux kernel drivers.
discussion positive
consensus
Commenters generally admire the project's creativity, particularly the repurposing of the Clicks keyboard. There is a technical debate regarding the optimal battery choice, with some favoring the modularity of 18650 cells and others preferring the volumetric density and slim profile of pouch batteries. A general agreement exists that while the hardware is dated, it remains viable for niche tasks like 'dumbphone' usage or minimal networking tools.
top insight
The technical explanation of how SMS storage works on cellular dongles clarifies that messages reside in the modem's memory or the SIM card rather than the Android userspace. This means users can retrieve messages via AT commands or libqmi without needing a compatible messaging app for the device's obsolete Android version. This insight decouples the software's UI limitations from the hardware's functional capabilities.
Generated by an LLM from the article and thread. Check the sources before relying on it.