January 29, 2023


Best Technology Perfection

Recycling Junk E-tags Into A LoRaWAN AQI Sensor

E-paper interfacing circuit is just a simple switched-mode power supply
Interfacing to E-paper shows is practically nothing to be frightened of

[Aduecho] experienced seen those people affordable eBay offers of e-paper-primarily based pricing tags, and was questioning if they could be hacked to execute some other tasks. Following splitting the scenario open up, the controller chip was found to be a SEM9110, with some NFC components assistance but little else. [aduecho] was hoping to construct some IoT-related air good quality indicator (AQI) units but the deficiency of a datasheet for SEM9110 as well as no sensors in position meant the only genuine program of motion was to junk the PCB and just keep the E-paper display screen and the batteries. These models appeared to be ‘new old’ inventory, so there was a very good chance that both equally would be contemporary and ripe for selecting.

The PCB [aduecho] arrived up with is mechanically the very same as the unique unit, but now sporting activities a Seeed studio Wio-E5 LoRa module, which utilizes the STM32WLE5 from ST for the major lifting. This has what seems like a Semtech SX126x built-in on-die (we just cannot believe of a sane way an genuine SX126x die could be flip-chip mounted, but you never know). Working with this module is a snap, needing only extremely minimum antenna-matching factors and a place of decoupling to perform. On the sensing side of issues, a Bosch BME680 gas sensor handling the AQI measurements, and a Bosch BMI270 6-axis IMU, presents a gyro and accelerometer, for all those planned user interaction attributes. As can be noticed from the schematic, interfacing the EPD is pretty uncomplicated, just a handful of elements are wanted to make the necessary bipolar gate voltages by using a simple SMPS circuit. The show controller handles it all internally, programmed through an SPI interface.

A person location we’re quite fond of in this job are the neat hand-drawn icons, and variable width font, offering the screen a form of notice-like high-quality when drawn on the very low-ish contrast e-paper display screen.

Air top quality measurement tasks grace these webpages from time to time, like this hacked Ikea Vindriktning, and this pretty similar Wio-E5-based job we included past thirty day period.