Problem on Raspberry PI 2B serial port /dev/ttyAMA0 write timeout

joaopagotto

Hello guys.

I have a problem taking the hair.

I do not know have gone for it, but what happens is that I made an application that works correctly in Windows , but when port this application in Qt 5.7.1 for Linux using a Raspberry PI 2B and its UART GPIO port.

It is called /dev/ttyAMA0

bool NetMaster485::open(const QString &port, qint32 baudRate)
{
   serialPort.setBaudRate(baudRate);
   serialPort.setDataBits(QSerialPort::Data8);
   serialPort.setParity(QSerialPort::NoParity);
   serialPort.setStopBits(QSerialPort::OneStop);
   serialPort.setFlowControl(QSerialPort::NoFlowControl);
   serialPort.setPortName(port);

   return serialPort.open(QIODevice::ReadWrite);
}

   QByteArray tx;
   
   ...
   
   serialPort.write(tx);
   serialPort.flush();
   if ( serialPort.waitForBytesWritten(timeoutTX) ) {
      return true;
   }
   return false; <<<

This aways emit error signal QSerialPort::SerialPortError(TimeoutError)

joaopagotto

Solved removed flush();

After:

 serialPort.flush();
   if ( serialPort.waitForBytesWritten(timeoutTX) ) {

Before:

   if ( serialPort.waitForBytesWritten(timeoutTX) ) {

SGaist

Hi,

Out of curiosity, why are you not using the asynchronous mechanism ?

joaopagotto

Hello friend , I am developing a RS485 communication protocol , and the communication would be the master layer. Ie it need to write on the bus and wait for the slave answer below , if not reply consider timeout . Ie is in a half duplex connection. This will be a free API compatible with Qt , Arduino , Microchip PIC .

Follow the project on this link:

https://github.com/JoaoPagotto/Net485