Thermometer based on STM32 single chip microcomputer (with face detection)

be based on STM32 Temperature measuring instrument of single chip microcomputer （ With face detection ）

Due to the need of medical development , In many cases , The general thermometer can't meet the requirements of fast and accurate temperature measurement , for example ： Station 、 metro 、 Human body temperature measurement is carried out in places with large population density such as airports .

The current design of this thermometer consists of temperature measuring Hardware + The upper computer software is combined , Mainly used in subway 、 Station entrance and other places , It can accurately recognize the face for temperature measurement , If someone's temperature exceeds the standard, it will give a voice prompt and save the current face photo .

1、​  Hardware selection and design ideas

(1). Device end

The main control single-chip microcomputer adopts STM32F103C8T6, The human body temperature measurement function adopts the non-contact infrared temperature measurement module .

(2). Design idea of upper computer

The upper computer adopts Qt5 Design ,Qt5 It's a set of bases C++ Language cross platform software library , Very powerful performance , At present, many mainstream desktop software uses QT Development . such as : Under Jinshan office -WPS, Byte hopping flag of - Cut and reflect , Blizzard Entertainment company - Many kinds of Game login wait .Qt It is also widely used in the field of Internet of vehicles , such as , harvard , tesla , The entire system of the central control screen of many cars, such as BYD, uses Qt Design .

In the temperature measurement project , The upper computer and STM32 Serial port protocol is used for communication between , The upper computer can open the default camera of the laptop , Face detection ; When a face is detected , control STM32 Measure the real-time temperature of the current human body , Then the temperature is transmitted to the upper computer for display ; When the temperature is normal , A green prompt is displayed on the upper computer “ The temperature is normal ”, And there is a voice broadcast , The sound of voice broadcast is generated by the sound card of the notebook . If the temperature is too high , The upper computer displays a red prompt “ Abnormal temperature , Please re measure ”, And there are voice broadcast prompts . When the temperature is too high , Will automatically save the current face photo , The photos are stored in the current software directory “face” Directory , The naming rule for files is “38.8_2022-01-05-22-12-34.jpg”, among 38.8 Indicates the temperature value , Followed by the date ( Mm / DD / yyyy HHM / S ).

(3) The running effect of upper computer

The upper computer needs to be connected STM32 The temperature data can only be obtained after the equipment , Click the open camera button on the software , Turn on camera , When a face is detected , The current measured temperature... Will be displayed below . If there is no connection STM32 equipment , A normal fixed temperature value will be displayed by default . Red characters on the right side of the interface , Indicates the time taken to process one frame of image , The better the computer performance , The faster the detection .

(4) How to run after getting the executable file ？

Decompress the package first , Get into “ Upper computer of thermometer - Executable file ” Catalog , take “haarcascade_frontalface_alt2.xml” copy to C Packing list .

Then double click. “FaceTemperatureCheck.exe” Run the program .

Device not connected , You can also turn on the camera to detect faces , But the temperature value is a fixed normal temperature range .

Two 、 Host computer design

2.1 Installation and compilation environment

If you need to compile and run the source code yourself , You need to install Qt5 development environment .

Download address :https://download.qt.io/official_releases/qt/5.12/5.12.0/

After downloading , First disconnect the computer network ( Otherwise, you will be prompted to enter QT Account number ), Then double click the installation package to install .

Installation can be done by selecting only one MinGW 32 Bit compilers are enough , See the screenshot below for details , choice “MinGW 7.3.0 32-bit” after , Just click next , Then wait for the installation to complete .

2.2 The overall effect of software code

After opening the project ( The suffix of engineering documents is xxx.pro), Click the green triangle button in the lower left corner to compile and run the program .

2.3 UI Design interface

2.4 Face detection core code

// Face detection code bool ImageHandle::opencv_face(QImage qImage) {     bool check_flag=0;     QTime time;     time.start();     static CvMemStorage* storage = nullptr;     static CvHaarClassifierCascade* cascade = nullptr;     // Model file path     QString face_model_file =QCoreApplication::applicationDirPath()+"/"+FACE_MODEL_FILE;     // Load classifier ： Frontal face detection     cascade =(CvHaarClassifierCascade*)cvLoad(face_model_file.toUtf8().data(),0,0,0);     if(!cascade)     {         qDebug()<<" Classifier loading error .\n";         return check_flag;     }     // Create memory space     storage =cvCreateMemStorage(0);     // Load the image to be detected     IplImage* img =QImageToIplImage(&qImage);     if(img ==nullptr )     {         qDebug()<<" Picture loading error .\n";         return check_flag;     }     double scale=1.2;     // Create image header address , And allocate storage space     IplImage* gray =cvCreateImage(cvSize(img->width,img->height),8,1);     // Create image header address , And allocate storage space     IplImage* small_img=cvCreateImage(cvSize(cvRound(img->width/scale),cvRound(img->height/scale)),8,1);     cvCvtColor(img,gray, CV_BGR2GRAY);     cvResize(gray, small_img, CV_INTER_LINEAR);     cvEqualizeHist(small_img,small_img);// Histogram equalization     /*      * Specify the corresponding face feature detection classifier , You can detect all the faces in the picture , And return the detected face through a rectangle .      * All in all 8 Parameters , Function description ：     Parameters 1： Represents the input image , Try to use grayscale images to speed up the detection .     Parameters 2： Express Haar Feature classifier , It can be used cvLoad() Function to load... From disk xml File as Haar Feature classifier .     Parameters 3： The memory cache area used to store the detected candidate targets .     Parameters 4： In two successive scans , The scale factor of the search window . The default is 1.1 That is to say, the search window expands in turn each time 10%     Parameters 5： Represents the minimum number of adjacent rectangles forming the detection target ( The default is 3 individual ). If the sum of the number of small rectangles constituting the detection target is less than min_neighbors - 1 Will be excluded . If min_neighbors by 0, Then the function returns all checked candidate rectangles without any operation , This setting value is generally used in the user-defined combination program of test results .     Parameters 6： Either use the default , Or use CV_HAAR_DO_CANNY_PRUNING, If set to CV_HAAR_DO_CANNY_PRUNING, So the function will use Canny Edge detection to exclude areas with too many or too few edges , Therefore, these areas are usually not the area where the face is located .     Parameters 7： Indicates the minimum value of the detection window , Generally, it can be set as the default .     Parameters 8： Indicates the maximum value of the detection window , Generally, it can be set as the default .     Function return value ： Function will return CvSeq object , This object contains a series of CvRect Represents the detected face rectangle .     */     CvSeq* objects =cvHaarDetectObjects(small_img,                                            cascade,                                            storage,                                            1.1,                                            3,                                            0/*CV_HAAR_DO_CANNY_PRUNING*/,                                            cvSize(50,50)/* Size determines how much time it takes to detect */);     qDebug()<<" Number of faces :"<<objects->total;     // Traverse to find the object and the surrounding painting box     QPainter painter(&qImage);// structure QPainter Drawing objects     QPen pen;     pen.setColor(Qt::blue);// Brush color     pen.setWidth(5);// The width of the brush     painter.setPen(pen);// Set brush     CvRect *max=nullptr;     for(int i=0;i<(objects->total);++i)     {         // Get the coordinate position, width and height information of the face         CvRect* r=(CvRect*)cvGetSeqElem(objects,i);         if(max==nullptr)max=r;         else         {             if(r->width>max->width||r->height>max->height)             {                 max=r;             }         }     }     // If you find the biggest target face     if(max!=nullptr)     {         check_flag=true;         // Draw a rectangle around the face area         painter.drawRect(max->x*scale,max->y*scale,max->width*scale,max->height*scale);     }     cvReleaseImage(&gray);  // Free picture memory     cvReleaseImage(&small_img);  // Free picture memory     cvReleaseHaarClassifierCascade(&cascade);// Free memory --> classifier     cvReleaseMemStorage(&objects->storage);// Free memory --> Detect all the faces in the picture     // Release picture     cvReleaseImage(&img);     qint32 time_ms=0;     time_ms=time.elapsed();     // Time consuming     emit ss_log_text(QString("%1").arg(time_ms));     // Save results     m_image=qImage.copy();     return check_flag; }

2.5 The configuration file ( Modify the parameters - Very important )

Parameter description ：

If there are multiple cameras on the computer , You can modify the camera number in the configuration file , The specific quantity will be automatically queried when the program starts , Print the code to the terminal .

If you compile and run the source code for the first time , After running ,

（1） You need to add the software source code in the directory “haarcascade_frontalface_alt2.xml” File copy to C Packing list , Or other non Chinese directories , The specific path can be modified in the configuration file , The default is C Packing list .

（2） You need to add the software source code in the directory “OpenCV-MinGW-Build-OpenCV-3.4.7\x86\mingw\bin” Copy all files in the directory to , The generated program execution file is in the same level directory .

Only in this way can the program run normally .

Threshold range of alarm temperature , You can also change , There are descriptions in the configuration file .

2.6 Voice prompt file and background image

Voice prompt file , The background image is loaded through the resource file .

The source file is stored in , Source code “FaceTemperatureCheck\res” Under the table of contents .

You can also replace yourself , Recompile the program to take effect .

2.7 Voice broadcast and image display processing code

// The result of image processing void Widget::slot_HandleImage(boolflag,QImage image) {     bool temp_state=0;     // Face detected     if(flag)     {         // Judge whether the temperature is normal         if(current_temp<MAX_TEMP && current_temp>MIN_TEMP)         {             temp_state=true;             // The display temperature is normal             ui->label_temp->setStyleSheet("color: rgb(0, 255, 127);font: 20pt \"Arial\";");             ui->label_temp->setText(QString("%1℃").arg(current_temp));         }         else// Voice Announcements , Abnormal temperature         {             temp_state=false;             // Display abnormal temperature             ui->label_temp->setStyleSheet("color: rgb(255, 0, 0);font: 20pt \"Arial\";");             ui->label_temp->setText(QString("%1℃").arg(current_temp));         }         // Get current ms Time         longlong currentTime =QDateTime::currentDateTime().toMSecsSinceEpoch();         // Determine whether the time interval has arrived         if(currentTime-old_currentTime>AUDIO_RATE_MS)         {             // Change the current time             old_currentTime=currentTime;             // The temperature is normal             if(temp_state)             {                 // Voice Announcements , The temperature is normal                 QSound::play(":/res/ok.wav");             }             // Abnormal temperature             else             {                 // Voice Announcements , Abnormal temperature                 QSound::play(":/res/error.wav");                 // Photo retention                 QString dir_str =QCoreApplication::applicationDirPath()+"/face";                 // Check that the directory exists , If not, create a new                 QDir dir;                 if(!dir.exists(dir_str))                 {                     bool res =dir.mkpath(dir_str);                     qDebug()<<" New directory status :"<< res;                 }                 // Save the pictures when the directory exists                 QDir dir2;                 if(dir2.exists(dir_str))                 {                     // Splice name                     QDateTime dateTime(QDateTime::currentDateTime());                     // Time effect : 2020-03-05 16:25::04 Monday                     QString qStr=QString("%1/%2_").arg(dir_str).arg(current_temp);                     qStr+=dateTime.toString("yyyy-MM-dd-hh-mm-ss-ddd");                     image.save(qStr+".jpg");                 }             }         }     }     else  // Do not display temperature     {         ui->label_temp->setStyleSheet("color: rgb(0, 255, 127);font: 20pt \"Arial\";");         ui->label_temp->setText("----");     }     // The result screen of the processing image     ui->widget_player->slotGetOneFrame(image); }

2.8 STM32 Temperature receiving and processing code

If a complete project is required , You can download it here ：https://download.csdn.net/download/xiaolong1126626497/85892490

// Refresh the serial port void Widget::on_pushButton_flush_uart_clicked() {     QList<QSerialPortInfo> UartInfoList=QSerialPortInfo::availablePorts();// Get the available serial port information     ui->comboBox_ComSelect->clear();     if(UartInfoList.count()>0)     {         for(int i=0;i<UartInfoList.count();i++)         {              if(UartInfoList.at(i).isBusy())// If the current serial port COM If you are busy, you will return to the truth , Otherwise return false              {                    QString info=UartInfoList.at(i).portName();                    info+="( Occupy )";                    ui->comboBox_ComSelect->addItem(info);// Add new entry options              }              else              {                   ui->comboBox_ComSelect->addItem(UartInfoList.at(i).portName());// Add new entry options              }         }     }     else     {         ui->comboBox_ComSelect->addItem(" No available COM mouth ");// Add new entry options     } } // Connect the temperature measuring equipment void Widget::on_pushButton_OpenUart_clicked() {     if(ui->pushButton_OpenUart->text()==" Connect the temperature measuring equipment ")  // Open the serial port     {         ui->pushButton_OpenUart->setText(" disconnect ");         /* Configure serial port information */         UART_Config->setPortName(ui->comboBox_ComSelect->currentText());  //COM The name of         if(!(UART_Config->open(QIODevice::ReadWrite)))      // Open attribute permissions         {             QMessageBox::warning(this,tr(" Status hint "),                                            tr(" Device connection failed !\n Please choose the right COM mouth "),                                            QMessageBox::Ok);                 ui->pushButton_OpenUart->setText(" Connect the temperature measuring equipment ");                 return;         }     }     else// Turn off the serial port     {         ui->pushButton_OpenUart->setText(" Connect the temperature measuring equipment ");         /* Turn off the serial port -*/         UART_Config->clear(QSerialPort::AllDirections);         UART_Config->close();     } } // Read the signal void Widget::ReadUasrtData() {     /* Returns the number of readable bytes */     if(UART_Config->bytesAvailable()<=0)     {         return;     }     /* Define byte array */     QByteArray rx_data;     /* Read all data in the serial port buffer */     rx_data=UART_Config->readAll();     // Conversion temperature     current_temp=rx_data.toDouble(); }