Need to understand the current sensor connection in this circuit

Question

I'm working on creating a smart power meter for my home, and I found this tutorial. I want to understand each part of the circuit, and the tutorial covers everything. However, it doesn't explain why the current sensor is connected to the ESP32 through three resistors and a capacitor. Is there a reason not to eliminate these passive elements and connect the current sensor directly to the ESP32?

I would appreciate it if you could also highlight any precautions or potential issues associated with this device that I should take into consideration.

Answer 1

Is there a reason not to eliminate these passive elements and connect the current sensor directly to the ESP32?

There is a very good reason.

If you looked at the schematic of the voltage sensing module would see a similar type of bias circuit as that formed by the three resistors with the current sensor. So, the three external resistors on the current sensor and, the internal bias circuits of the ZMPT101B module are both needed to produce a mid-range DC offset equivalent to 50% of the DC power voltage: -

The above is somebody's artistic-like tear-down of the internal circuit on the ZMPT101B module and, I've circled in red where the bias circuits are that centre the signal output between the power rails.

The ESP32's ADC circuits need a "neutral" signal at 50% of the power rail voltage: -

Picture from ZMPT101B SINGLE PHASE AC VOLTAGE SENSOR MODULE that shows that the output has a "neutral" point at +2.5 volts and, that's what the external three resistors do for the current sensing module.