read_bpm.py

# read_bpm.py
import threading
import serial

bpm_value = 0

def read_serial():
    global bpm_value
    ser = serial.Serial('COM9', 9600)
    while True:
        try:
            line = ser.readline().decode().strip()
            if line.isdigit():
                bpm_value = int(line)
        except:
            continue

t = threading.Thread(target=read_serial, daemon=True)
t.start()