Send integer from STM32 board to Qt app with serial communication using UART

Question

I'm trying to click on the read button on my Qt app and read an integer from an STM32 board.

I can send a frame from the Qt app to the STM32 board which is "5\r" and the board reads it normally, but when the board sends the integer it dosen't reach the QT app. This is the code for sending the first frame to the STM32:

send "5\r" to stm32

connect(button2, &QPushButton::clicked, [=]() {
 textBrowser->clear();
 Uart* uart = Uart::getInstance();
 QSerialPort* serialPort = uart->getSerialPort();
 char delimiter1[2] = "*";
 QByteArray packet1;
 packet1.append("5");
 // packet1.append(delimiter1);
 packet1.append("\r");
 qDebug() << "packet1 :"<< packet1 ;
 if (serialPort->isOpen() && serialPort->isWritable()) {
 qint64 bytesWritten = serialPort->write(packet1);
 if (bytesWritten == -1) {
 qDebug() << "Error: Failed to write data to serial port";
 } else {
 qDebug() << bytesWritten << "bytes written to serial port";
 textBrowser->append("Request send ...");
 }
 } else {
 qDebug() << "Error: Serial port is not open or not writable";
 }
 QString style = "color: #AA4A44;"; // Adresse de couleur pour le vert (green)
 textBrowser->setStyleSheet(style);

The code that sends the integer to the Qt app:

char data = '1'; // Define a character variable with the value '1'
HAL_UART_Transmit(&UartHandle, (uint8_t *)&data, 1, 500);

The code for receiving the integer that doesn't work:

QString lastResponse = ""; // Initialiser lastResponse à une chaîne vide
QByteArray responseData;
while (serialPort->waitForReadyRead(1000)) {
 responseData.append(serialPort->readAll());
}
if (!responseData.isEmpty()) {
 lastResponse = QString::fromUtf8(responseData);
 textBrowser->clear();
 textBrowser->append("recived data :");
 qDebug() << "Received data:" << lastResponse;
 qDebug() << "Received data:" << responseData;
 textBrowser->append(lastResponse);
} else {
 qDebug() << "No data received from serial port";
 textBrowser->append("No data received from serial port");
}

What is the solution for receiving the integer?

• pmacfarlane: You don't really show much context for your "code receiving integer" stuff. There will be some delay between the STM32 receiving something and it sending the reply. If you don't account for that, and just instantly check for a response, you might assume you did not get a response.
• hcheung: Forget about Qt app for time being, as a debugging step, run a terminal program on your PC, will you be able to receive what the STM32 sent?
• Jens: And once you made sure, that a stupid terminal works thus really knowing, what the serial settings look like, then you should have a connection between QSerialPort and your code: connect(serialPort, SIGNAL(readyRead()), SLOT(handleReadyRead())); Once you got that, come back here and rephrase your question accordingly
• Ilya: char delimiter1[2] = "*"; here and later on you manipulate individual characters, but you use double quotes as if it's a string. Replace " with ' in several places, where you operate on a char level. Also, check raw values you receive, before any processing. char '1' is raw 0x31.