I have been using what are called Chinese MEC10 soil moisture sensor to control drip irrigation. Once a couple of these sensors went kapot i dismantled one to find it has an STM32L452RE as main controller, an lmv321 as a possible comparator, some bits for temperature (couldn't exactly get to see an ic) an RS485 to transmit data. The rest are step up or down transistors for 3.3 and 5V power or resist/capacitors for the comparator. As one of the manufacturers like JCXT claim these work on time domain reflectometry i expected an cd4060 or 74AC14 as a signal generator to get into a 4-10ns range required in literature to get into the frequency range to avoid aliasing n get real signal amplitude /frequency or time so as to get soil moisture or conductivity. But there was none. Instead if the signal is generated and received at stm32 then it can only get in the 100s of microseconds or thru registers into hundreds of nanoseconds. I need to find how these MEC10s work. Comments will really