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1.2 How ``ws_test.py`` Works?
==============================

The communication between Pico and Sunfounder Controller is based on the ``websocket protocol``.

* `WebSocket - Wikipedia <https://en.wikipedia.org/wiki/WebSocket>`_

The specific workflow of APP Control gameplay is as follows:

    |flowchart_app_control|

.. code-block:: python

    from ws import WS_Server
    import json
    import time

    NAME = 'my_esp8266'

    ## Client Mode
    # WIFI_MODE = "sta"
    # SSID = "YOUR SSID HERE"
    # PASSWORD = "YOUR PASSWORD HERE"

    ## AP Mode
    WIFI_MODE = "ap"
    SSID = ""
    PASSWORD = "12345678"


    ws = WS_Server(name=NAME, mode=WIFI_MODE, ssid=SSID, password=PASSWORD)
    ws.start()

    led = machine.PWM(machine.Pin(15))
    led.freq(1000)
    potentiometer = machine.ADC(28)

    def on_receive(data):
        print(data)
        
        # output
        value = data['H']
        led.duty_u16(value*655)
        
        # input
        value=potentiometer.read_u16()
        ws.send_dict['G'] = value

    ws.on_receive = on_receive

    def main():
        print("start")
        while True:
            ws.loop()

    main()


This code constitutes the basic framework of APP control. Here, you need to pay attention to the following two parts:

1. Setup websocket

    There are two connection mode between Sunfounder Controller and Pico: One is **AP** mode, the other is **STA** mode.

    * **AP Mode**: You need to connect Sunfounder Contorller to the hotspot released by pico.
    * **STA Mode**: You need to connect Sunfounder Controller and pico to the same LAN.
    
    The default connection mode is **AP Mode**: The Pico releases the hotspot (the Wifi name is ``NAME`` in the code, here is ``my_esp8266``), the mobile phone (tablet) is connected to this WLAN. 
    This mode allows you to remotely control pico in any situation, but will make your phone (tablet) temporarily unable to connect to the Internet.

    .. code-block:: python
        :emphasize-lines: 3,4,5,6,8,9,10,11

        NAME = 'my_esp8266'

        ## Client Mode
        # WIFI_MODE = "sta"
        # SSID = "YOUR SSID HERE"
        # PASSWORD = "YOUR PASSWORD HERE"

        ## AP Mode
        WIFI_MODE = "ap"
        SSID = ""
        PASSWORD = "12345678"

        ws = WS_Server(name=NAME, mode=WIFI_MODE, ssid=SSID, password=PASSWORD)
        ws.start()

    You can also use **STA** mode: Let the pico connects to your home WLAN, and your mobile phone (tablet) should also be connected to the same WLAN. 
    
    This mode is opposite to the **AP** mode and will not affect the normal use of the mobile phone (tablet), but will limit your pico from leaving the WLAN radiation range.

    The way to start this mode is to comment out the three lines under ``## AP Mode``, uncomment the three lines under ``## Client Mode``, and change the ``SSID`` and ``PASSWORD`` to your home WIFI at the same time.

    .. code-block:: python
        :emphasize-lines: 3,4,5,6,8,9,10,11

        NAME = 'my_esp8266'

        ## Client Mode
        WIFI_MODE = "sta"
        SSID = "YOUR SSID HERE"
        PASSWORD = "YOUR PASSWORD HERE"

        ## AP Mode
        # WIFI_MODE = "ap"
        # SSID = ""
        # PASSWORD = "12345678"

        ws = WS_Server(name=NAME, mode=WIFI_MODE, ssid=SSID, password=PASSWORD)    
        ws.start()

    After completing the connection mode settings, Websocket will set up and start the server.

    .. code-block:: python

        ws = WS_Server(name=NAME, mode=WIFI_MODE, ssid=SSID, password=PASSWORD)    
        ws.start()    

#. Responding

    The specific operation code of Pico and Sunfounder Controller is written on the ``on_receive()`` function. Usually, we need to write the codes for APP to control Pico on the front and the codes for APP to show Pico sensor data on the back.

    .. code-block:: python

        def on_receive(data):
            print(data)
            
            # output
            value = data['H']
            led.duty_u16(value*655)
            
            # input
            value=potentiometer.read_u16()
            ws.send_dict['G'] = value

        ws.on_receive = on_receive

    Finally, ``on_receive()`` will be assigned to ``ws.on_receive`` and then called by ``ws.loop``.