testLed.py

import serial
from flask import Flask, render_template, request

app=Flask(__name__)

ser=serial.Serial('COM4', 9600, timeout=1)

@app.route("/", methods=['POST', 'GET'])
def led():
    if request.method=='POST':
        if request.form['submit']=='LED On ':
            ser.write(str.encode('1'))
        elif request.form['submit']=='LED Off':
            ser.write(str.encode('0'))
    return render_template('home.html', title = 'Arduino')

if __name__ == "__main__":
    app.run()