transfer binary file from pc(ubuntu) to raspberry(rasbian) without lrzsz or kermit, e

Hello Community,

i'm trying to transfer a binary file or file from my PC(ubuntu OS) to an embedded system raspberry(raspbian OS) over serial port. Physically, my PC is connected to my raspberry through FTDI Chip TTL-232R-Rpi Kabel(USB-to-UART).
I use an own application on my pc developed over qtcreator with QSerialPort library to configure and open the device /dev/ttyUSB0(COM3 for Windows OS) of my pc.

Code:

---

m_serial = new QSerialPort(this)
m_serial->setPortName("/dev/ttyUSB0)
m_serial->setBaudRate(QSerialPort::Baud115200);
m_serial->setDataBits(QSerialPort::Data8);
m_serial->setParity(QSerialPort::NoParity);
m_serial->setStopBits(QSerialPort::OneStop);
m_serial->setFlowControl(QSerialPort::NoFlowControl);
m_serial->open(QIODevice::ReadWrite);

---

All work fine. I can connect the pc to the raspberry with login. The serial connection currently is working but this is controlled by the Raspberry console like a remote connection to Raspberry and goes directly to console and login(raspberry).
On my PC, being connected on the raspberry console i run the following code "dd bs=1 count=138333 | base64 -d > myfile_to_receive \r"

Code:

---

void MainWindow::on_btnRecv_clicked()
{
    m_command = "dd bs=1 count=138333 | base64 -d > test_32_test \r";
    m_serial->write(m_command.toLocal8Bit());
}

---

to wait and receive via serial port all binary data from pc, it works fine.
Unfortunately, when i send data from my pc using the same application but via QProcess or system with the following code "cat file_to_send > /dev/ttyUSB0"

Code:

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system("cat file_to_send > /dev/ttyUSB0");

---

i cannot send my file and i get the message "cannot create /dev/ttyUSB0: Device or resource busy". I'm trying to remove the file LCK..ttyUSB0 created by QSerialport but nothing works well(Sending).
Can somebody help me, please?
Thank you in advance

N.B: transfer binary file over serial port without protocol like kermit, or zmodem or putty, etc.... as also no ethernet or ssh connection

I don't think either QProcess nor system() understand shell syntax like ">", they simply execute a single program.

Have you tried using "dd" with "if=file_to_send of=/dev/ttyUSB0"?

Cheers,
_

Thank you for your reply.
i am trying with "dd" but i always receive the same error message "cannot open /dev/ttyUSB0: Device or resource busy". May be i cannot utilize in the same time with 2 differents(QSerialPort and System/or QProcess) process the device /dev/ttyUSB0. do you have any idea?
Thank you!

this is my code cpp.

Code:

---

#include "mainwindow.h"
#include "ui_mainwindow.h"
 
MainWindow::MainWindow(QWidget *parent) :
    QMainWindow(parent),
    ui(new Ui::MainWindow)
{
    ui->setupUi(this);
 
    m_stdOut_Proc = "";
    m_stdOut_Serial = "";
    m_command = "";
 
    m_serial = new QSerialPort(this);
    openSerialPort();
 
}
 
MainWindow::~MainWindow()
{
    if(m_serial->isOpen())
        m_serial->close();
    delete ui;
}
 
void MainWindow::openSerialPort()
{
    m_serial->setPortName("/dev/ttyUSB0");
    m_serial->setBaudRate(QSerialPort::Baud115200);
    m_serial->setDataBits(QSerialPort::Data8);
    m_serial->setParity(QSerialPort::NoParity);
    m_serial->setStopBits(QSerialPort::OneStop);
    m_serial->setFlowControl(QSerialPort::NoFlowControl);
 
    connect(m_serial, &QSerialPort::readyRead, this, &MainWindow::readyreadStdOut_QSerial);
    if(m_serial->open(QIODevice::ReadWrite))
        qDebug()<<"Device opened successful";
    else
    {
        qDebug()<<"Device opened fail";
        return;
    }
}
 
void MainWindow::readyreadStdOut_QSerial()
{
    m_stdOut_Serial = m_serial->readAll();
    qDebug()<< m_stdOut_Serial;
    ui->labelQSerial->setText(m_stdOut_Serial);
}
 
void MainWindow::on_btnWrite_clicked()
{
    m_command = ui->lineEditCommand->text() +"\r";
    m_serial->write(m_command.toLocal8Bit());
    ui->lineEditCommand->setText("");
}
 
void MainWindow::on_btnQuitApp_clicked()
{
    qApp->quit();
}
 
void MainWindow::on_btnRecv_clicked() //after connection and login to raspberry. i run this command in console raspi
{
    m_command = "dd bs=1 count=138333 | base64 -d > file_to_receive\r";
    m_serial->write(m_command.toLocal8Bit());
}
 
 
void MainWindow::on_btnFirmware_clicked() // i try to start this command in shell pc but it doesn't work. i receive a error message: "cannot open /dev/ttyUSB0: Device or resource busy"
{
    system("dd if=file_to_send of=/dev/ttyUSB0");
}

---

this is my h-file:

Code:

---

#ifndef MAINWINDOW_H
#define MAINWINDOW_H
 
#include <QMainWindow>
#include <QSerialPort>
#include <QSerialPortInfo>
 
#include <QDebug>
#include <QDataStream>
#include <QByteArray>
 
namespace Ui {
class MainWindow;
}
 
class MainWindow : public QMainWindow
{
    Q_OBJECT
 
public:
    explicit MainWindow(QWidget *parent = nullptr);
    ~MainWindow();
 
private slots:
    void readyreadStdOut_QSerial();
 
    void on_btnWrite_clicked();
    void on_btnQuitApp_clicked();
    void on_btnFirmware_clicked();
    void on_btnRecv_clicked();
 
private:
    void writeDate_test(const QByteArray &data);
    void openSerialPort();
 
private:
    Ui::MainWindow *ui;
 
    QSerialPort *m_serial;
    QString m_stdOut_Serial;
    QString m_command;
 
 
};
 
#endif // MAINWINDOW_H

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nobody can help me?

It is normal if You have COM port opened by application and trying to open this port from another process.

thank you for your reply. i have found out a solution.

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Added after 4 minutes:

thank you very much anda_skoa,
you given me a solution but i misused it.