Chapter 13 74HC595 & LED Bar Graph
===================================
We have used LED bar graph to make a flowing water light, in which 10 GPIO ports 
of ESP32-S3 is occupied. More GPIO ports mean that more peripherals can be connected 
to ESP32-S3, so GPIO resource is very precious. Can we make flowing water light 
with less GPIO? In this chapter, we will learn a component, 74HC595, which can 
achieve the target.

Project 13.1 Flowing Water Light
--------------------------------
Now let’s learn how to use the 74HC595 IC chip to make a flowing water light using 
less GPIO.

Component List
^^^^^^^^^^^^^^^
- ESP32-S3-WROOM x1
- GPIO Extension Board x1
- 830 Tie-Points Breadboard x1
- 74HC595 x1
- Resistor 220Ω  x8
- LED Bar Graph x1
- Jumper Wire x15

Connect
^^^^^^^^

.. image:: img/connect/13.png

Code
^^^^^^^
In this project, we will make a flowing water light with a 74HC595 chip to learn 
about its functions. Move the program folder :file:`Super_Starter_Kit_for_ESP32_S3/Python/Python_Codes` to disk(D) in advance with the path of “D:/Micropyth
on_Codes”. 

Open “Thonny”, click :file:`This computer/D:/Micropython_Codes/13.1_Flowing_Water_Light`. Select “my74HC595.py”, right click your mouse to select “Upload to /”, wait 
for “my74HC595.py”to be uploaded to ESP32-S3 and then double click “Flowing_Water_Light.py”.

**13.1_Flowing_Water_Light**

.. image:: img/software/13.1.png

Click“Run current script” and you will see that Bar Graph LED starts with the 
flowing water pattern flashing from left to right and then back from right to 
left. If it displays nothing, maybe the LED Bar is connected upside down, please 
unplug it and then re-plug it reversely.


The following is the program code:

.. code-block:: python

    import time
    from my74HC595 import Chip74HC595

    chip = Chip74HC595(12,13,14,-1)#STCP，SHCP，DS，OE
    # ESP32-12:   74HC595-STCP(12)
    # ESP32-13:   74HC595-SHCP(11)
    # ESP32-14:   74HC595-DS(14)
    # ESP32-GND : 74HC595-OE(13)

    while True:
        x=0x01
        for count in range(8):
            chip.shiftOut(1,x)
            x=x<<1;
            time.sleep_ms(300)
        x=0x01
        for count in range(8):
            chip.shiftOut(0,x)
            x=x<<1
            time.sleep_ms(300)