My first pomodoro app for M5Stack

pomodoro.py

from m5stack import *
import utime
import math

cnt = 0
m_cnt = cnt
start = False
done = False

def init():
    global cnt
    global m_cnt
    global done
    global start
    done = False
    start = False
    lcd.clear(lcd.BLACK)
    cnt = 10 * 60 * 25
    m_cnt = cnt
    lcd.setCursor(0, 0)
    lcd.setColor(lcd.RED)
    lcd.font(2)
    lcd.println("Pomodoro v0.0.1")

def redraw(cnt):
    global m_cnt
    lcd.setCursor(lcd.CENTER, 100)
    lcd.setColor(lcd.WHITE)
    if start :
        lcd.setColor(lcd.GREEN)
    lcd.textClear(lcd.CENTER, 100, "xx:xx")
    minute = '%02d' % math.floor(cnt / 60)
    second = '%02d' % (cnt % 60)
    lcd.println("{0}:{1}".format(minute, second))
    # Graph
    lcd.roundrect(10, 130, 300, 10, 4, lcd.WHITE, lcd.BLACK)
    lcd.roundrect(10, 130, round(300 * ( 1 - cnt * 10 / m_cnt)), 10, 1, lcd.WHITE, lcd.WHITE)


init()
redraw(math.floor(cnt / 10))


while True:
    utime.sleep(0.1)

    if buttonA.wasReleased():
        start = True
        redraw(math.floor(cnt / 10))

    if buttonC.wasReleased():
        init()
        redraw(math.floor(cnt / 10))

    if done :
        continue

    if start : 
        cnt -= 1

    if cnt <= 0 :
        lcd.setCursor(0, 0)
        lcd.clear(lcd.BLUE)
        lcd.setColor(lcd.RED)
        lcd.font(2)
        lcd.print("Finish!")
        done = True

    if not start :
        continue

    if cnt % 10 == 0 :
        redraw(math.floor(cnt / 10))