The "Useless" ESL seems to be new old stock without any public documentation. It has a 2.9-inch E-Ink display, a SEM9110 SOC controller which is also w/o any documents, 2 CR2450 batteries, and a nice case.
After I received those ESLs, I want to test whether the EPD(WF0290T5PCFxxxxx) is compatible with the wildely used Waveshare's driver, but found the FPC contact point is reversed compare with normal EPD, thus I flyed some cables from the original mainboard to a STM32 bluepill board, after configuration, luckily the EPD works :)
4 years ago I played the BME680 together with a 2.3Inch E-ink display, planned to make a small beautiful device like "SHT31 SMART GADGET".
But due to many reasons, it was given up. This time I can reuse it and bring the sensor data to the internet.
The system HW components:
BME680: low power gas sensor which can measure AQI, together with Temperature, Humidity, and atmospheric pressure. The average current consumption at 0.33Hz datarate for T&H&P, 0.33mHz AQI is 0.1mA.
Seed E5 Lora module: It's a small module based on STM32WLE5JC, it was choosed for sensor control and commit the sensor data to the free LoraWan, in this project is TTN(The Things Network). This module is also a low current consumption module, with 2.1uA sleep current.
2.9 Inch E-Paper Display: which is also a low power cunsomption element, comes from the ESL.
2 PCs CR2450 3V battery: around 2*600mAh capacity, come from the ESL.
1 PC BMI270 IMU sensor: ultra-low power IMU sensor, planned used for wakeup the sensor and use motion as user settings input, like adjust the clock, show historical data...but due to out of stock in JLCPCB, so it's not mounted on the PCB.
1PC vibration sensor: Due to above BMI270 is not avalible, using a low cost and 0 current consumption as user wakeup, which can trigg one measurement by the user, or show historical data, I'm not sure.
1PC Beeper: Planned for alarm, like the smoke detector function, or used for fart detection alarm :)
2PCs LED: Indicate the Lorawan link status? not fixed yet.
2 Antennas: 1 PCB antenna and 1 spring antenna, will check which one is better.
1 PCB: From JLCPCB together with SMT function, but not all the components are soldered by JLC, for eg. the MOSFET for the EPD and battery contactors are removed from the ESL's original PCB.
1 Housing: Comes from the ESL, but with some curtting in order to fit with the new added modules.
There is no issue with the HW, but the external battery measurement circuit is not needed, since E5 module can measure the Vbat by itself.
1. EPD basic driver is woking.
2. LoraWan is working, the sensor can commit the data to TTN
3. Cayenne Low Power Payload is working, can check the sensor data in the APP and browser
currently on the handwritting like font on the EPD.