Lack of Data Read From Serial Port

**lucille** · 23rd April 2024, 12:38

Hi, ? am ne in Qt. I was trying to send data from STM32f407vg to Qt. The data is produced by RTC module and gives time, date (for example, 2024-03-11T17:01:24+08:00Monday). However the data read by Qt is not full in text edit always. It is like a loop below and repeated always.

```
2
2
2
20
20
20
202
202
202
2024
2024
2024
2024-
2024-
2024-
2024-0
2024-0
2024-0
2024-03
2024-03
2024-03
2024-03-
2024-03-
2024-03-
2024-03-1
2024-03-1
2024-03-1
2024-03-11
2024-03-11
2024-03-11
2024-03-11T
2024-03-11T
2024-03-11T
2024-03-11T1
2024-03-11T1
2024-03-11T1
2024-03-11T17
2024-03-11T17
2024-03-11T17
2024-03-11T17:
2024-03-11T17:
2024-03-11T17:
2024-03-11T17:0
2024-03-11T17:0
2024-03-11T17:0
2024-03-11T17:01
2024-03-11T17:01
2024-03-11T17:01
2024-03-11T17:01:
2024-03-11T17:01:
2024-03-11T17:01:
2024-03-11T17:01:1
2024-03-11T17:01:1
2024-03-11T17:01:1
2024-03-11T17:01:17
2024-03-11T17:01:17
2024-03-11T17:01:17
2024-03-11T17:01:17+
2024-03-11T17:01:17+
2024-03-11T17:01:17+
2024-03-11T17:01:17+0
2024-03-11T17:01:17+0
2024-03-11T17:01:17+0
2024-03-11T17:01:17+08
2024-03-11T17:01:17+08
2024-03-11T17:01:17+08
2024-03-11T17:01:17+08:
2024-03-11T17:01:17+08:
2024-03-11T17:01:17+08:
2024-03-11T17:01:17+08:0
2024-03-11T17:01:17+08:0
2024-03-11T17:01:17+08:0
2024-03-11T17:01:17+08:00
2024-03-11T17:01:17+08:00
2024-03-11T17:01:17+08:00
2024-03-11T17:01:17+08:00M
2024-03-11T17:01:17+08:00M
2024-03-11T17:01:17+08:00M
2024-03-11T17:01:17+08:00Mo
2024-03-11T17:01:17+08:00Mo
2024-03-11T17:01:17+08:00Mo
2024-03-11T17:01:17+08:00Mon
2024-03-11T17:01:17+08:00Mon
2024-03-11T17:01:17+08:00Mon
2024-03-11T17:01:17+08:00Mond
2024-03-11T17:01:17+08:00Mond
2024-03-11T17:01:17+08:00Mond
2024-03-11T17:01:17+08:00Monda
2024-03-11T17:01:17+08:00Monda
2024-03-11T17:01:17+08:00Monda
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday
2024-03-11T17:01:17+08:00Monday

When ? tested in termit terminal, the data is read properly like
2024-03-11T17:01:17+08:00Monday

The data is transmitted in stm32

Qt Code:

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sprintf(buffer, "%04d-%02d-%02dT%02d:%02d:%02d%+03d:%02d%s\n",
	  	  	  year, month, date, hour, minute, second, zone_hr, zone_min, DAYS_OF_WEEK[dow]);
 
HAL_UART_Transmit(&huart3, buffer, strlen(buffer), 1000);

sprintf(buffer, "%04d-%02d-%02dT%02d:%02d:%02d%+03d:%02d%s\n",
	  	  	  year, month, date, hour, minute, second, zone_hr, zone_min, DAYS_OF_WEEK[dow]);

HAL_UART_Transmit(&huart3, buffer, strlen(buffer), 1000);

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The data is read by qt code

Qt Code:

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QStringList bufferSplit = serialBuffer.split("\n"); 
    if(bufferSplit.length() < 3)
    {
        serialData = serialPort.readAll();
        serialBuffer += QString::fromStdString(serialData.toStdString());
    }
 
    else //bufferSplit[0] is a good value
    {
        qDebug() << bufferSplit;
        serialBuffer = "";
    }
 
    ui->display_line->append(bufferSplit[0]);
 
}

QStringList bufferSplit = serialBuffer.split("\n"); 
    if(bufferSplit.length() < 3)
    {
        serialData = serialPort.readAll();
        serialBuffer += QString::fromStdString(serialData.toStdString());
    }

    else //bufferSplit[0] is a good value
    {
        qDebug() << bufferSplit;
        serialBuffer = "";
    }

    ui->display_line->append(bufferSplit[0]);

}

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The data is splitted (according to \n) and stored in the buffer to be read.

The bufferlist is below and ? have taken 0. index

QList("2024-03-11T17:01:24+08:00Monday", "2024-03-11T17:01:25+08:00Monday", "")