Communication between WEMOS and raspberry pie

Raspberry pie operation

Use Python establish Http The server

from flask import Flask
app = Flask(__name__)

@app.route('/')
def hello_world():
    return 'Hello, World!'

if __name__ == '__main__':
    app.run(host = "0.0.0.0", port = '3009')

• Define the return contents of the root directory

Make with raspberry pie WeMos The background of

Raspberry pie http The server

• effect
  • Use flask, Create a simple... On raspberry pie web The server
  • wemos Put forward HTTP Of get Request to get the report data

Code

#  Default access ‘/data’ Path will call subordinate functions 
""" pi_backend.py This is a REST relay server running on the Pi for the Arduino to relay data to on the way to the Cloud. Effectively functions as a gateway for the edge devices. """

from flask import Flask, request, render_template, Response
#import client #uncomment when integrating with the client.py API

# Create the flask app
app = Flask(__name__)

# This is for the callback, which should be defined to
# with the following signature:
# def callback(temp, humid, light)
#

_callback_ = None

# Create just a single route to read data from the Arduino
@app.route('/data', methods = ['GET'])
def addData():
    ''' The one and only route. It extracts the data from the request, converts to float if the data is not None, then calls the callback if it is set '''

    global _callback_

    tempStr = request.args.get('temp')
    humidStr = request.args.get('humid')
    lightStr = request.args.get('light')

    temp = float(tempStr) if tempStr else None
    humid = float(humidStr) if humidStr else None
    light = float(lightStr) if lightStr else None

    if _callback_:
        _callback_(temp = temp, humid = humid, light = light)
    
    return "OK", 200


def set_callback(callback):
    ''' Sets the callback. @param callback The callback with signature def callback(temp, humid, light) '''

    global _callback_

    _callback_ = callback

def demo_callback(temp, humid, light):
    ''' Demo callback that just prints the data passed in. '''

    if temp is not None:
        print("\nTemperature = %3.2f" % temp)

    if humid is not None:
        print("Humidity = %3.2f" % humid)

    if light is not None:
        print("Light = %3.2f" % light)

    if temp is None and humid is None and light is None:
        print("\n*** Called without any parameters. ***")

    print("\n")

def main():
    set_callback(demo_callback)
    app.run(host = "0.0.0.0", port = '3009')


if __name__ == '__main__':
    main()

WeMos send out HTTP request

• explain
  • WeMos and Pi It can realize interworking through LAN , Raspberry pie has been set up as a server above , The current part needs to pass WeMos send out HTTP request

WeMos Connect wifi

• Burn the following code into wemos modular

#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>
#include <WiFiClient.h>

const char* ssid = "ChinaNet-G3GN201"; //Your Wifi's SSID
const char* password = "qq7729577855"; //Wifi Password

void setup(void){
    
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  Serial.println("");
  
  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
}

void loop(void){
    

}

WeMos send out HTTP request

• In the previous example , establish http The relevant code of the request , In order to simulate the process of data generation by actual sensors , Every time 5 Send a data per second .

#include <ESP8266WiFi.h>
#include <ESP8266HTTPClient.h>
#include <WiFiClient.h>

const char* ssid = "ChinaNet-G3GN201"; //Your Wifi's SSID
const char* password = "qq7729577855"; //Wifi Password

WiFiClient wifiClient;
const char* piAt = "http://192.168.1.248:3009/"; //change to your Pi's IP

void setup(void){
    
  Serial.begin(115200);
  WiFi.begin(ssid, password);
  Serial.println("");
  
  // Wait for connection
  while (WiFi.status() != WL_CONNECTED) {
    
    delay(500);
    Serial.print(".");
  }
  Serial.println("");
  Serial.print("Connected to ");
  Serial.println(ssid);
  Serial.print("IP address: ");
  Serial.println(WiFi.localIP());
}

void loop(void){
    
  Serial.print("Sending...");
  if (WiFi.status() == WL_CONNECTED){
    
    HTTPClient http;
    
    String url = piAt;
    url += "data?temp=31.2&humid=76&light=87"; //hardcoded values for example only
    
    http.begin(wifiClient,url);
    int returnCode = http.GET();   //perform a HTTP GET request
    
    if (returnCode > 0){
    
      String payload = http.getString();
      Serial.println(payload);
    }
    http.end();
    
  } else {
    
    Serial.println("WiFi disconnected");
  }
  delay(5000);  //Five second delay
}