Alibaba cloud development board haas510 parses serial port JSON data and sends attributes

Abstract ： This paper introduces the use of HaaS510 Receive data from serial port , Extract the required attribute values from the data , And send it to the IOT platform . The data format received from the serial port is JSON Format .

The experiment purpose ： Through the upper computer to haas510 send out JSON character string , from HaaS510 Parse and extract the specified attribute value , And send it to the cloud platform .

Hardware ：haas510 (2.0 edition ）,USB A serial port

Software ：win7 x64,vscode

Catalog

1. Introduction to key knowledge points

2. Write source code

3. Observe the operation effect

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1. Introduction to key knowledge points

In this experiment, the computer is used as the upper computer , Upper computer passes USB Serial port and HaaS510 Connect . If you use other microprocessors , As long as it can be sent JSON Format string , The effect is the same . The key knowledge points of the experiment are 2 individual .

First point , How to convert the data received by the serial port into a string . We know , Serial communication , yes 8 position 8 Receive data bit by bit , Equivalent to one by one 8 An array of bit data , This array is not a string at first , We can understand it as a series of hexadecimal data . So we need to restore this data to a string , And then we can parse it .

See documentation

Alibaba cloud development board HaaS510 Respond to UART Serial port instruction https://blog.csdn.net/youngwah292/article/details/120377994?spm=1001.2014.3001.5501https://blog.csdn.net/youngwah292/article/details/120377994?spm=1001.2014.3001.5501

Second point , How to parse a string into key attribute values . This knowledge point is also explained in detail through documents .

Alibaba cloud development board HaaS510 analysis JSON data

2. Write source code

This article provides the source code directly

var iot = require('iot');
var network = require('network');
var uart = require('uart');
var net = network.openNetWorkClient();
/*  For information about device triples, please refer to common In the catalog iot Component description  */
var productKey = 'gcCCCCCCu2';
var deviceName = 'ceCCCCCCC01';
var deviceSecret = 'eeSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSb3a9';
//  Build Internet of things connection instances 
var device;
var lightSwitch = 0;

// The test parses a json character string , The string of the serial port is not parsed here , Instead, it parses a fixed array of strings .
var json = '{"uid":"123456","beizhu":"5557589","shijian":"20210919"}';
var obj = JSON.parse(json);

  // user uart
  var serial = uart.open({
    id: 'UART2'
  });

  var msgbuf = [97, 98, 99, 100];

  function ArrayToString(fileData) {
    var dataString = "";
    for (var i = 0; i < fileData.length; i++) {
      dataString += String.fromCharCode(fileData[i]);
    }
    return dataString;
  }


net.on('connect', function () {
    device = iot.device({
        productKey: productKey,
        deviceName: deviceName,
        deviceSecret: deviceSecret,
        region: 'cn-shanghai',
        success: function () {
            console.log('iot: [success] connect');
        },
        fail: function () {
            console.log('iot: [failed] connect');
        }
    });
})

setInterval(function () {
    lightSwitch = 1 - lightSwitch;

    // user uart send data
    serial.write(msgbuf);
    // The parsed content is shown below 
    console.log(obj);         
    console.log(obj.uid);    
    console.log(obj.beizhu);   
    console.log(obj.shijian);

/*  Error model    iot.postProps({
                       payload: {LightSwitch:'0'}
                    })*/
/* Correct demonstration , To send attributes , You have to use stringify Talent */
    device.postProps(
        JSON.stringify({
            LightSwitch: lightSwitch
        })
    );
  
  }, 5000);
// user uart data receive 
serial.on('data', function(data) {
  console.log('uart receive data is ' + ArrayToString(data));  
    json = ArrayToString(data);
    // Then parse the string 
    obj = JSON.parse(json); 
// Here are a few key attribute values to send json = '{"uid":"123456","beizhu":"5557589","shijian":"20210919"}'
    device.postProps( 
                  JSON.stringify({
                    uid:obj.uid,beizhu:obj.beizhu,shijian:obj.shijian
                                 })
                   );

});

The key code is after the serial port receives the data , The operation of parsing data .

json = ArrayToString(data);
    // Then parse the string 
    obj = JSON.parse(json); 
     // Here are a few key attribute values to send json = '{"uid":"123456","beizhu":"5557589","shijian":"20210919"}'
    device.postProps( 
                  JSON.stringify({
                    uid:obj.uid,beizhu:obj.beizhu,shijian:obj.shijian
                                 })
                   );

3. Observe the operation effect

First connect the hardware

After the source code provided in this experiment runs , There will be multiple experimental effects , As shown in the figure below . No more screenshots , Interested readers can check out my other HaaS510 article .

  This experiment focuses on the 5 Experimental results , That is, send a message through the upper computer JSON character string , see HaaS510 Whether the value can be parsed and reported to the cloud in real time .

  From the computer to HaaS510 Send data through the user serial port of

{"uid":"888888","beizhu":"666666","shijian":"20210920"}

It can be observed that this data is parsed , Through debugging, the serial port also has corresponding display .

  The data has been uploaded to the cloud . remarks 、 Time 、uid、 The main light switches have been changed accordingly .

  thus , Successful experiment .

Work here , You can use HaaS510 Designed an Internet of things device . Use one MCU Write functional code . Upload the data to the cloud to JSON Format sent to HaaS510, The attribute value reporting function can be realized . What about? , Easy ！

If you still haven't mastered everything , Then I suggest you refer to other articles of the author .

Give people roses , Fragrance in hand .