二进制图片直接显示在HTML中

参考:

https://developer.mozilla.org/en-US/docs/Web/HTTP/Basics_of_HTTP/Data_URIs

参考Data_URIs的方式,把二进制文件直接显示在网页中

格式

data:[<mediatype>][;base64],<data>

例如

data:text/plain,文本数据
data:text/html,HTML代码
data:text/html;base64,base64编码的HTML代码
data:text/css,CSS代码
data:text/css;base64,base64编码的CSS代码
data:text/javascript,Javascript代码
data:text/javascript;base64,base64编码的Javascript代码
data:image/gif;base64,base64编码的gif图片数据
data:image/png;base64,base64编码的png图片数据
data:image/jpeg;base64,base64编码的jpeg图片数据
data:image/x-icon;base64,base64编码的icon图片数据
  • base64
    是否通过base64编码

  • ,data
    二进制文件内容

比如要显示一个png图片的二进制文件,可以先读取图片内容,做base64的编码

<img src="data:image/png ;base64, <data>">

L298P 电机驱动 Shield

L298P 电机驱动 shield

这个shield也不知道啥意思,怎么翻译,大概就是扩展板的意思?
买了一块L298P电机驱动的扩展板,没找到资料,搜索一下只有英文的,就翻译一下了

来源

https://electropeak.com/learn/interfacing-l298p-h-bridge-motor-driver-shield-with-arduino/
一个购买连接,不过也没找到更多资料了

  • 先看看图

以下是说明

可以控制两台直流电机:

VMS: Module voltage(外部供电)
GND: Ground
MA1: Positive end for motor A (A电机正极)
MA2: Negative end for motor A (A电机负极)
MB1: Positive end for motor B (B电机正极)
MB2: Negative end for motor B (B电机负极)
PWMA: Speed control signal for motor A – This pin is connected to pin 10 of Arduino

A电机PWM输入 速度控制---也就是arduino的D10

PWMB: Speed control signal for motor B – This pin is connected to pin 11 of Arduino

B电机PWM输入 速度控制---也就是arduino的D11

ENA: Control signal for motor A – If HIGH, motor is in direct mode and if LOW, motor is rotating in reverse. This pin is connected to pin 12 of Arduino

A电机正反转控制---arduino的D12

ENB: Control signal for motor B – If HIGH, motor is in direct mode and if LOW, motor is rotating in reverse. This pin is connected to pin 13 of Arduino

B电机正反转控制---arduino的D13

Buzzer for make sound:
BUZ: Buzzer pin – This pin is connected to pin 4 of Arduino

蜂鸣器 D4

Connection for control servo motor:
SER: PWM pin for control servo motor – This pin is connected to pin 9 of Arduino

伺服电机(舵机) D9-PWM

Bluetooth connections:
BT2: Bluetooth Pins including +(3.3V) pins, (GND), RX (connected to D0) and TX (connected to D1)

连接蓝牙

Ultrasonic sensor connection:
ULT: connection pins to ultrasonic sensor including +(5V), (GND), Return (connected to D9) and Trigger (connected to D8)

超声波传感器

RBG LED connection:
RGB: RGB: For connection to RGB LED including pins B (connected to D6), G (connected to D5) and R (connected to D3)

RGB LED灯 R-D3 G-D5 B-D6 也不知道在哪亮。。

Other connections:
A/D: Analog and digital pins A0 to A5 for sensor and module use
D2: Digital pin 2 for sensor and module use
RS: Reset pin
GND: Ground
VCC: Board power supply – 3V, 5V

板供电

另一个地方找的示例代码,也是购买页。

https://protosupplies.com/product/l298p-motor-driver-shield/

/*
*  L298P Motor Shield
*  Code for exercising the L298P Motor Control portion of the shield
*  The low level motor control logic is kept in the function 'Motor'
*/
// The following pin designations are fixed by the shield
int const BUZZER = 4;
//  Motor A
int const ENA = 10;  
int const INA = 12;
//  Motor B
int const ENB = 11;  
int const INB = 13;

int const MIN_SPEED = 27;   // Set to minimum PWM value that will make motors turn
int const ACCEL_DELAY = 50; // delay between steps when ramping motor speed up or down.
//===============================================================================
//  Initialization
//===============================================================================
void setup()
{
  pinMode(ENA, OUTPUT);   // set all the motor control pins to outputs
  pinMode(ENB, OUTPUT);
  pinMode(INA, OUTPUT);
  pinMode(INB, OUTPUT);
  pinMode(BUZZER, OUTPUT);
  Serial.begin(9600);     // Set comm speed for serial monitor messages
}
//===============================================================================
//  Main
//===============================================================================
void loop()
{
  // Run both motors Forward at 75% power
  Motor('C', 'F', 75);   
  delay(3000);

  // Run both motors in Reverse at 75% power but sound beeper first
  Motor('C', 'F', 0);  // Stop motors
  delay(1000);
  digitalWrite(BUZZER,HIGH);delay(500);digitalWrite(BUZZER,LOW); 
  delay(500);
  digitalWrite(BUZZER,HIGH);delay(500);digitalWrite(BUZZER,LOW); 
  delay(1000);
  Motor('C', 'R', 75);  // Run motors forward at 75%
 delay(3000); 

  // now run motors in opposite directions at same time at 50% speed
  Motor('A', 'F', 50);
  Motor ('B', 'R', 50);
  delay(3000);

  // now turn off both motors
  Motor('C', 'F', 0);  
  delay(3000);

  // Run the motors across the range of possible speeds in both directions
  // Maximum speed is determined by the motor itself and the operating voltage

  // Accelerate from zero to maximum speed
  for (int i = 0; i <= 100; i++)
  {
    Motor('C', 'F', i);
    delay(ACCEL_DELAY);
  }
  delay (2000);

  // Decelerate from maximum speed to zero
  for (int i = 100; i >= 0; --i)
  {
    Motor('C', 'F', i);
    delay(ACCEL_DELAY);
  }
  delay (2000);

  // Set direction to reverse and accelerate from zero to maximum speed
  for (int i = 0; i <= 100; i++)
  {
    Motor('C', 'R', i);
    delay(ACCEL_DELAY);
  }
  delay (2000);

  // Decelerate from maximum speed to zero
  for (int i = 100; i >= 0; --i)
  {
    Motor('C', 'R', i);
    delay(ACCEL_DELAY);
  }
  // Turn off motors
  Motor('C', 'F', 0);
  delay (3000);
}
/*
 * Motor function does all the heavy lifting of controlling the motors
 * mot = motor to control either 'A' or 'B'.  'C' controls both motors.
 * dir = Direction either 'F'orward or 'R'everse
 * speed = Speed.  Takes in 1-100 percent and maps to 0-255 for PWM control.  
 * Mapping ignores speed values that are too low to make the motor turn.
 * In this case, anything below 27, but 0 still means 0 to stop the motors.
 */
void Motor(char mot, char dir, int speed)
{
  // remap the speed from range 0-100 to 0-255
  int newspeed;
  if (speed == 0)
    newspeed = 0;   // Don't remap zero, but remap everything else.
  else
    newspeed = map(speed, 1, 100, MIN_SPEED, 255);

  switch (mot) {
    case 'A':   // Controlling Motor A
      if (dir == 'F') {
        digitalWrite(INA, HIGH);
      }
      else if (dir == 'R') {
        digitalWrite(INB, LOW);
      }
      analogWrite(ENA, newspeed);
      break;

    case 'B':   // Controlling Motor B
      if (dir == 'F') {
        digitalWrite(INB, HIGH);
      }
      else if (dir == 'R') {
        digitalWrite(INB, LOW);
      }
      analogWrite(ENB, newspeed);
      break;

    case 'C':  // Controlling Both Motors
      if (dir == 'F') {
        digitalWrite(INA, HIGH);
        digitalWrite(INB, HIGH);
      }
      else if (dir == 'R') {
        digitalWrite(INA, LOW);
         digitalWrite(INB, LOW);
      }
      analogWrite(ENA, newspeed);
      analogWrite(ENB, newspeed);
      break;
  }
  // Send what we are doing with the motors out to the Serial Monitor.

  Serial.print ("Motor: ");
  if (mot=='C')
      Serial.print ("Both");
    else
      Serial.print (mot);
  Serial.print ("t Direction: ");
  Serial.print (dir);
  Serial.print ("t Speed: ");
  Serial.print (speed);
  Serial.print ("t Mapped Speed: ");
  Serial.println (newspeed);
}

微信小程序登录

问题

1、调用wx.login后code传给后端需要保存session_token,但是这个session_token无法设置缓存时间,有效时间和用户操作有关,只能通过前端wx.checksession判断有效性.
2、用户信息、手机号等授权接口解密都需要使用这个session_token。

解决方式

取消原先系统的登录验证方式,直接用checksession方法检查用户登录状态
前端直接用wx.checksession作为判断用户登录状态的方法,session无效再调用wx.login更新后端数据

流程

wx.checksession
->ok->判断用户已登录

->无效->执行->wx.login->用返回的code传给后端更新session_token

app.js

    wx.checkSession().then(
      ()=>{}, 
      ()=>{
        return utils.authLogin()
      }).finally(()=>{
        this.getUserInfo().then(res=>{
          this.globalData.userInfo = res.data;
          if(res.data.is_registered == 0){
            wx.navigateTo({
              url: '/pages/getUserProfile/getUserProfile'
            })
          } 
        })
      })

utils.js

module.exports = {
  formatTime,
  request: function(params){
    return new Promise((resolve, reject)=>{
      wx.request({
        ...params,
        dataType: 'json',
        header: {
          Authorization: 'Bearer ' + wx.getStorageSync('authToken')
        },
        success:res=>{
          if(res.data.code == 4003){
            wx.navigateTo({
              url: '/pages/index/forbidden'
            })
          }
          if(res.data.code == 403){
            this.authLogin()
          }
          resolve(res.data)
        },
        error:error=>{
          reject(error)
        }
      })
    })
  },
  login: function(){
    return new Promise((resolve, reject)=>{
      wx.login({
        success:res=>{
          resolve(res)
        },
        error:error=>{
          reject(error)
        }
      })
    })
  },
  authLogin: function(){
    this.login().then(res=>{
      this.request({
        url: 'http://www.pp.com/api/user/login',
        data: {
          code: res.code
        }
      }).then(res=>{
        wx.setStorageSync('authToken', res.data.token)
      }).catch(e=>{

      })

    })
  }
}

ESP8266 arduino wifi文档阅读

来源

https://arduino-esp8266.readthedocs.io/en/3.0.2/ideoptions.html
https://www.arduino.cc/en/Reference/WiFi

WIFI库

连接示例

#include <ESP8266WiFi.h>
void setup()
{
  Serial.begin(115200);
  Serial.println();

  WiFi.begin("network-name", "pass-to-network");

  Serial.print("Connecting");
  while (WiFi.status() != WL_CONNECTED)
  {
    delay(500);
    Serial.print(".");
  }
  Serial.println();

  Serial.print("Connected, IP address: ");
  Serial.println(WiFi.localIP());
}
void loop(){}

包含的class

  • Station 连接wifi

  • SOFT-AP 作为软路由-提供其他设备联网能力

  • Scan 扫描范围内的SSID

  • Client

    WiFiClient()
    connected()
    connect()
    write()
    print()
    println()
    available()
    read()
    flush()
    stop()
  • WiFi Multi 记录多个ap并在断线时选择信号最好的wifi连接

    #include <ESP8266WiFiMulti.h>
    
    ESP8266WiFiMulti wifiMulti;
    // WiFi connect timeout per AP. Increase when connecting takes longer.
    const uint32_t connectTimeoutMs = 5000;
    
    void setup()
    {
      // Set in station mode
      WiFi.mode(WIFI_STA);
    
      // Register multi WiFi networks
      wifiMulti.addAP("ssid_from_AP_1", "your_password_for_AP_1");
      wifiMulti.addAP("ssid_from_AP_2", "your_password_for_AP_2");
      wifiMulti.addAP("ssid_from_AP_3", "your_password_for_AP_3");
    }
    
    void loop()
    {
      // Maintain WiFi connection
      if (wifiMulti.run(connectTimeoutMs) == WL_CONNECTED) {
          ...
      }
    }
  • Server
    例子

    #include <ESP8266WiFi.h>
    
    const char* ssid = "********";
    const char* password = "********";
    
    WiFiServer server(80);
    
    void setup()
    {
      Serial.begin(115200);
      Serial.println();
    
      Serial.printf("Connecting to %s ", ssid);
      WiFi.begin(ssid, password);
      while (WiFi.status() != WL_CONNECTED)
      {
        delay(500);
        Serial.print(".");
      }
      Serial.println(" connected");
    
      server.begin();
      Serial.printf("Web server started, open %s in a web browser\n", WiFi.localIP().toString().c_str());
    }
    
    // prepare a web page to be send to a client (web browser)
    String prepareHtmlPage()
    {
      String htmlPage;
      htmlPage.reserve(1024);               // prevent ram fragmentation
      htmlPage = F("HTTP/1.1 200 OK\r\n"
                   "Content-Type: text/html\r\n"
                   "Connection: close\r\n"  // the connection will be closed after completion of the response
                   "Refresh: 5\r\n"         // refresh the page automatically every 5 sec
                   "\r\n"
                   "<!DOCTYPE HTML>"
                   "<html>"
                   "Analog input:  ");
      htmlPage += analogRead(A0);
      htmlPage += F("</html>"
                    "\r\n");
      return htmlPage;
    }
    
    void loop()
    {
      WiFiClient client = server.available();
      // wait for a client (web browser) to connect
      if (client)
      {
        Serial.println("\n[Client connected]");
        while (client.connected())
        {
          // read line by line what the client (web browser) is requesting
          if (client.available())
          {
            String line = client.readStringUntil('\r');
            Serial.print(line);
            // wait for end of client's request, that is marked with an empty line
            if (line.length() == 1 && line[0] == '\n')
            {
              client.println(prepareHtmlPage());
              break;
            }
          }
        }
    
        while (client.available()) {
          // but first, let client finish its request
          // that's diplomatic compliance to protocols
          // (and otherwise some clients may complain, like curl)
          // (that is an example, prefer using a proper webserver library)
          client.read();
        }
    
        // close the connection:
        client.stop();
        Serial.println("[Client disconnected]");
      }
    }
  • UDP UDP通信

    begin()
    available()
    beginPacket()
    endPacket()
    write()
    parsePacket()
    peek()
    read()
    flush()
    stop()
    remoteIP()
    remotePort()

下载离线网站

wget --mirror --convert-links --adjust-extension --page-requisites 
--no-parent http://example.org
  • --mirror – Makes (among other things) the download recursive.
  • --convert-links – convert all the links (also to stuff like CSS stylesheets) to relative, so it will be suitable for offline viewing.
  • --adjust-extension – Adds suitable extensions to filenames (html or css) depending on their content-type.
  • --page-requisites – Download things like CSS style-sheets and images required to properly display the page offline.
  • --no-parent – When recursing do not ascend to the parent directory. It useful for restricting the download to only a portion of the site.

简写

wget -mkEpnp http://example.org

wget 准确率不高,HTTrack是更好用的工具

https://www.httrack.com/
HTTrack is a free (GPL, libre/free software) and easy-to-use offline browser utility.