AC current recorder based on the blackpill STM32F411CEU.
Device uses a current transformer for measure AC current.
If the RMS current is exceeded the threshold, a new data record will be written to SD in the data.csv file.

The state_recorder directory contains a complete STM32CubeIDE project.

Device takes 3200 samples of the one signal period (50Hz) every 1s. The current transformer and measure resistor R3 ratio (current/voltage) is defined as the const value currentTransformerRatio in the input_monitor.h file. For my DIY transformer it is 0.08132V/A. You can update it value accordingly to yours transformer. After acquisition a signal is filtered by simple the moving average filter.

When the current level is exceeded the threshold defined as const currentThreshold = 0.6A in the input_monitor.h file, the data starts to be integrate. The data is saved as a new record in the data.csv file after the current drops below the threshold.

A consumed energy is calculated with the voltage defined as const powerVoltage in the input_monitor.h file. Currently it is 230V.

It's best to open the data.csv in the LibreOffice Calc. The MS excel has problems with commas in floating point numbers. A single record in a CSV file has the form:
Index, name, event time, duration, avr. I [A], Energy [kWh]

master - contain English version
polish - contain Polish version

Better resolution is in the schema.png file.