Chapter 3 LED Bar
=========================
We have learned how to control a LED blinking, next we will learn how to control 
a number of LEDs.

Project 3.1 Flowing Light
--------------------------
In this project, we use a number of LEDs to make a flowing light.

Component List
^^^^^^^^^^^^^^^
- ESP32-S3-WROOM x1
- GPIO Extension Board x1
- 830 Tie-Points Breadboard x1
- Resistor 220Ω x10
- Jumper Wire x10
- LED Bar Graph x1

Connect
^^^^^^^^

.. image:: img/connect/3.png

Code
^^^^^^^
This project is designed to make a flowing water lamp. Which are these actions: 
First turn LED #1 ON, then turn it OFF. Then turn LED #2 ON, and then turn it 
OFF... and repeat the same to all 10 LEDs until the last LED is turns OFF. This 
process is repeated to achieve the “movements” of flowing water.

**03.1_FlowingLight**

Move the program folder :file:`Super_Starter_Kit_for_ESP32_S3/Python/Python_Codes` to 
disk(D) in advance with the path of “D:/Micropython_Codes”. Open “Thonny”，click :file:`This computer/D:/Micropython_Codes/03.1_FlowingLight` and double click “FlowingLight.py”.

.. image:: img/software/3.1.png

Click “Run current script” shown in the box above, LED Bar Graph will light up 
from left to right and then back from right to left.

.. image:: img/phenomenon/3.1.png

The following is the program code:

.. code-block:: python

    import time
    from machine import Pin

    pins=[21,47,48,38,39,40,41,42,2,1]

    def showled():                 
        length=len(pins)               
        for i in range(0,length):
            led=Pin(pins[i],Pin.OUT)
            led.value(1)
            time.sleep_ms(100)
            led.value(0) 
        for i in range(0,length):
            led=Pin(pins[(length-i-1)],Pin.OUT)
            led.value(1)
            time.sleep_ms(100)
            led.value(0)

    while True:
        showled()