i2c = I2C(scl=Pin(22), sda=Pin(21), freq=100000)
oled_width = 128
oled_height = 32
oled = ssd1306.SSD1306_I2C(oled_width, oled_height, i2c)

rtc = machine.RTC()

ntptime.settime()

while True:
    t = rtc.datetime()
    time_string = "{:02d}:{:02d}:{:02d}".format(t[4], t[5], t[6])
    oled.fill(0)
    oled.text(time_string, 0, 0)
    oled.show()
    utime.sleep(1)