8" eTape Liquid Level Sensor + extras [Discontinued] _RPI_HAT_Displays It communicates using hardware SPI

It communicates using hardware SPI (MISO

We tweaked the output to be 5

to add new wireless capabilities

Thats easy - it could have used an embedded RFID/NFC transponder

or creative lighting projects

8" eTape Liquid Level Sensor + extras [Discontinued] _RPI_HAT_Displays It communicates using hardware SPIThe eTape Liquid Level Sensor is a solid state sensor with a resistive output that varies with the level of the fluid. It does away with clunky mechanical floats, and easily interfaces with electronic control systems. The eTape sensor's envelope is compressed by the hydrostatic pressure of the fluid in which it is immersed. This results in a change in resistance that corresponds to the distance from the top of the sensor to the surface of the fluid.