Python current monitor

Save this as current_monitor.py:

#!/usr/bin/env python3
import csv
import sys
import time
from datetime import datetime

import board
import busio
from adafruit_ina219 import ADCResolution, BusVoltageRange, Gain, INA219


def create_sensor():
    i2c = busio.I2C(board.SCL, board.SDA)
    sensor = INA219(i2c)

    # Conservative configuration suitable for many low-voltage bench setups.
    sensor.bus_adc_resolution = ADCResolution.ADCRES_12BIT_32S
    sensor.shunt_adc_resolution = ADCResolution.ADCRES_12BIT_32S
    sensor.bus_voltage_range = BusVoltageRange.RANGE_16V
    sensor.gain = Gain.DIV_8_320MV
    return sensor


def open_csv(path):
    file_obj = open(path, "a", newline="", encoding="utf-8")
    writer = csv.writer(file_obj)
    if file_obj.tell() == 0:
        writer.writerow(
            ["timestamp", "bus_voltage_V", "shunt_voltage_mV", "current_A", "power_W"]
        )
        file_obj.flush()
    return file_obj, writer


def main():
    csv_path = sys.argv[1] if len(sys.argv) > 1 else "current_log.csv"
    interval_s = float(sys.argv[2]) if len(sys.argv) > 2 else 1.0

    sensor = create_sensor()
    csv_file, writer = open_csv(csv_path)

    print("Raspberry Pi lab power supply current monitor")
    print(f"Logging to: {csv_path}")
    print("Press Ctrl+C to stop.")
    print("timestamp,bus_voltage_V,shunt_voltage_mV,current_A,power_W")

    try:
        while True:
            timestamp = datetime.now().isoformat(timespec="seconds")
            bus_voltage = sensor.bus_voltage
            shunt_voltage_mv = sensor.shunt_voltage / 1000.0
            current_a = sensor.current / 1000.0
            power_w = sensor.power / 1000.0

            row = [
                timestamp,
                f"{bus_voltage:.3f}",
                f"{shunt_voltage_mv:.3f}",
                f"{current_a:.6f}",
                f"{power_w:.6f}",
            ]
            print(",".join(row))
            writer.writerow(row)
            csv_file.flush()
            time.sleep(interval_s)
    except KeyboardInterrupt:
        print("\nStopped.")
    finally:
        csv_file.close()


if __name__ == "__main__":
    main()

Make it executable and run it:

chmod +x current_monitor.py
python3 current_monitor.py current_log.csv 1.0