Driver CH341 USB Adapter Serial Port or QSerialPort not Works in Linux

linux qt linux-kernel qtserialport
Kijam picture Kijam · Apr 13, 2014 · Viewed 9.9k times · Source

The following code works for me correctly in Windows, but Linux does not work. I am using the same PC, both operating systems are installed native. I do not use virtual machine. I need to work on Linux. I have tried in different linux distributions and does not work anywhere.

// In the main class:
QSerialPortInfo info = XXXX; // Generally in Linux: /dev/ttyUSB0, in win: COM1
QSerialPort serial;
QObject::connect(&serial, SIGNAL(readyRead()), this, SLOT(onReadyRead()), Qt::DirectConnection);
QObject::connect(&serial, SIGNAL(bytesWritten(qint64)), this, SLOT(onBytesWritten(qint64)), Qt::DirectConnection);
QObject::connect(&serial, SIGNAL(error(QSerialPort::SerialPortError)), this, SLOT(onError(QSerialPort::SerialPortError)), Qt::DirectConnection);

// Slot
void MyClass::onReadyRead()
{
    qDebug()<<"Signal onReadyRead";
    buffer_mutex.lock();
    buffer += serial.readAll();
    qDebug()<<"Read: "<<qstr_to_hexstr(buffer);
    bufferNotEmpty.wakeAll();
    buffer_mutex.unlock();
}

void MyClass::onError(QSerialPort::SerialPortError error) {
    qCritical()<<"Serial Port Error: "<<(int)error;
}

void MyClass::onBytesWritten(qint64 size){
    qDebug()<<"onBytesWritten: "<<size;
}


// In another place I did:
serial.setPort(info); 
if(!serial.open(QIODevice::ReadWrite))
    return false;

qDebug()<<"Init Setting!...";

if(!serial.setBaudRate(QSerialPort::Baud9600))
    qCritical()<<"Error in setBaudRate";
if(!serial.setDataBits(QSerialPort::Data8))
    qCritical()<<"Error in setDataBits";
if(!serial.setParity(QSerialPort::EvenParity))
    qCritical()<<"Error in setParity";
if(!serial.setStopBits(QSerialPort::OneStop))
    qCritical()<<"Error in setStopBits";
if(!serial.setFlowControl(QSerialPort::SoftwareControl))
    qCritical()<<"Error in setFlowControl";
if(!serial.setDataTerminalReady(true))
    qCritical()<<"Error in setDataTerminalReady";

qDebug()<<"Setting ready!...";

If sending 1 byte the device responds and sends the data correctly.

Example:

// In the main class:
const char enq[2] = {0x05, '\0'};
serial.write (enq);

// In onReadyRead:
serial.readAll(); // Works on Win / Linux

If sent a more than 1 byte device does not respond the request in linux.

Example:

// In the main class:
const char command[6] = {0x02, 'S', '1', 0x03, 'a', '\0'};
serial.write(command);

// In onReadyRead
serial.readAll(); // Works only in Win

This event is triggered only in windows. In linux it never works, not received or arrives in bad format and never recognized the remote device.

My log in Windows:

{Debug}         Init Setting!... 
{Debug}         Setting ready!...
{Debug}         Write:  " 0x05 "
{Debug}         onBytesWritten:  1 
{Debug}         buffer wait!... 
{Debug}         Signal onReadyRead 
{Debug}         Read:  " 0x02 `@ 0x03 #" 
{Debug}         buffer size:  5 
{Critical}      Serial Port Error:  0 
{Debug}         Write:  " 0x02 S1 0x03 a" 
{Debug}         onBytesWritten:  5 
{Debug}         buffer wait!... 
{Debug}         Signal onReadyRead 
{Debug}         Read:  " 0x02 S100 0x0A 00000000000000000 0x0A 00000479" 
{Debug}         buffer size:  32 
{Debug}         buffer wait!... 
{Debug}         Signal onReadyRead 
{Debug}         Read:  " 0x02 S100 0x0A 00000000000000000 0x0A 00000479 0x0A 00000 0x0A 00000330 0x0A 00000 0x0A 0061 0x0A 0000 0x0A " 
{Debug}         buffer size:  64 
{Debug}         Signal onReadyRead 
{Debug}         buffer wait!... 
{Debug}         Read:  " 0x02 S100 0x0A 00000000000000000 0x0A 00000479 0x0A 00000 0x0A 00000330 0x0A 00000 0x0A 0061 0x0A 0000 0x0A X-XXXXXXXX 0x0A XXXXXXXXX 0x0A 221715 0x0A 120414 0x0A  0x03  0x1B " 
{Debug}         buffer size:  103 
{Critical}      Serial Port Error:  0

(I replace the actual response of the device by the 'X' characters)

My log in Linux:

{Debug}         Init Setting!... 
{Debug}         Setting ready!...
{Debug}         Write:  " 0x05 "
{Debug}         onBytesWritten:  1 
{Debug}         buffer wait!... 
{Debug}         Signal onReadyRead 
{Debug}         Read:  " 0x02 `@ 0x03 #" 
{Debug}         buffer size:  5 
{Critical}      Serial Port Error:  0 
{Debug}         Write:  " 0x02 S1 0x03 a" 
{Debug}         onBytesWritten:  5 
{Debug}         buffer wait!... 
{Debug}         buffer wait!... 
{Debug}         buffer wait!... 
{Debug}         buffer wait!... 
{Debug}         buffer wait!... 
{Debug}         buffer wait!... 
{Debug}         buffer wait!... 
{Debug}         buffer wait!... 
{Debug}         buffer wait!... 
{Debug}         buffer wait!... 
{Debug}         timeout!... (15 sec for timeout)

USB Serial Adapter: CH340

In Windows: USB\VID_1A86&PID_7523&REV_0254
In Linux:
    Apr 13 01:16:58 kali kernel: [47844.260136] usb 2-1: new full-speed USB device number 16 using uhci_hcd
    Apr 13 01:16:58 kali kernel: [47844.428098] usb 2-1: New USB device found, idVendor=1a86, idProduct=7523
    Apr 13 01:16:58 kali kernel: [47844.428115] usb 2-1: New USB device strings: Mfr=0, Product=2, SerialNumber=0
    Apr 13 01:16:58 kali kernel: [47844.428126] usb 2-1: Product: USB2.0-Ser!
    Apr 13 01:16:58 kali kernel: [47844.431268] ch341 2-1:1.0: ch341-uart converter detected
    Apr 13 01:16:58 kali kernel: [47844.445398] usb 2-1: ch341-uart converter now attached to ttyUSB0
    Apr 13 01:16:58 kali mtp-probe: checking bus 2, device 16: "/sys/devices/pci0000:00/0000:00:1d.0/usb2/2-1"
    Apr 13 01:16:58 kali mtp-probe: bus: 2, device: 16 was not an MTP device

PD: Sorry for my English, try to do my best with Google Translator :(...

More information 1:

Apr 13 04:10:55 kali kernel: [ 4872.627980] tty ttyUSB0: serial_write - 1 byte(s)
Apr 13 04:10:55 kali kernel: [ 4872.629763] tty ttyUSB0: serial_chars_in_buffer
Apr 13 04:10:55 kali kernel: [ 4872.629778] tty ttyUSB0: serial_wait_until_sent
Apr 13 04:10:55 kali kernel: [ 4872.638252] tty ttyUSB0: serial_chars_in_buffer
Apr 13 04:10:55 kali kernel: [ 4872.638267] tty ttyUSB0: serial_write_room
Apr 13 04:10:55 kali kernel: [ 4872.638278] tty ttyUSB0: serial_chars_in_buffer
Apr 13 04:10:55 kali kernel: [ 4872.638287] tty ttyUSB0: serial_write_room
Apr 13 04:10:55 kali kernel: [ 4872.639438] tty ttyUSB0: serial_chars_in_buffer
Apr 13 04:10:55 kali kernel: [ 4872.639458] tty ttyUSB0: serial_write_room
Apr 13 04:10:55 kali kernel: [ 4872.639475] tty ttyUSB0: serial_chars_in_buffer
Apr 13 04:10:55 kali kernel: [ 4872.639488] tty ttyUSB0: serial_write_room
Apr 13 04:10:56 kali kernel: [ 4873.641799] tty ttyUSB0: serial_ioctl - cmd 0x540b
Apr 13 04:10:56 kali kernel: [ 4873.646884] tty ttyUSB0: serial_write - 5 byte(s)
Apr 13 04:10:56 kali kernel: [ 4873.647152] ch341-uart ttyUSB0: ch341_update_line_status - multiple status change
Apr 13 04:10:56 kali kernel: [ 4873.647176] ch341-uart ttyUSB0: ch341_update_line_status - delta=0x01
Apr 13 04:10:56 kali kernel: [ 4873.647384] tty ttyUSB0: serial_chars_in_buffer
Apr 13 04:10:56 kali kernel: [ 4873.647401] tty ttyUSB0: serial_wait_until_sent
Apr 13 04:10:56 kali kernel: [ 4873.649144] ch341-uart ttyUSB0: ch341_update_line_status - multiple status change
Apr 13 04:10:56 kali kernel: [ 4873.649166] ch341-uart ttyUSB0: ch341_update_line_status - delta=0x01
Apr 13 04:10:56 kali kernel: [ 4873.692152] ch341-uart ttyUSB0: ch341_update_line_status - multiple status change
Apr 13 04:10:56 kali kernel: [ 4873.692170] ch341-uart ttyUSB0: ch341_update_line_status - delta=0x01
Apr 13 04:10:56 kali kernel: [ 4873.694133] ch341-uart ttyUSB0: ch341_update_line_status - multiple status change
Apr 13 04:10:56 kali kernel: [ 4873.694148] ch341-uart ttyUSB0: ch341_update_line_status - delta=0x01

I rebuild ch341.c and add:

if (!delta)
    return;

dev_info(&port->dev, "%s - delta=0x%02X\n", __func__, delta); // <---- New Line

if (delta & CH341_BIT_CTS)
    port->icount.cts++;
if (delta & CH341_BIT_DSR)
    port->icount.dsr++;
if (delta & CH341_BIT_RI)
    port->icount.rng++;
if (delta & CH341_BIT_DCD) {
    port->icount.dcd++;
    tty = tty_port_tty_get(&port->port);
    if (tty) {
        usb_serial_handle_dcd_change(port, tty,
                    status & CH341_BIT_DCD);
        tty_kref_put(tty);
    }
}

delta=0x01 in the log is flag: 

#define CH341_BIT_CTS 0x01

More information 2:

In the thread of write / read I hope for wakeAll, running on onReadyRead. If you pass a second make a readAll before checking if the buffer is empty. example:

// In the main class:
QWaitCondition bufferNotEmpty;

// In my function write/read:
serial.write(data, size);
buffer_mutex.lock();
while(time(NULL)-timeStart<timeoutWait && serial.isOpen()) {
    buffer += serial.readAll();
    if(buffer.count()>0){
        qDebug()<<"buffer size: "<<buffer.count();
        //Interprete the buffer here...

        if(bufferComplete) 
            break;
    }
    qDebug()<<"buffer wait!...";
    bufferNotEmpty.wait(&buffer_mutex, 1000);
}
buffer.clear();
buffer_mutex.unlock();

More information 3:

My Kernel is 3.12.6, but i updated from GitHub this file an rebuild this drivers:

https://github.com/torvalds/linux/blob/master/drivers/usb/serial/ch341.c https://github.com/torvalds/linux/blob/master/drivers/usb/serial/usb-serial.c (commit d9a38a8741fdffabc32e6d0943b1cdcf22712bec)

Answer

Kijam picture Kijam · Apr 14, 2014

Thanks to the developers of Linux, solved my problem, the CH34x driver not implemented parity in the maillist is the link PATCH for those who have this problem in the future, not whether they apply to the official kernel, for now only way is rebuild the driver.

http://marc.info/?l=linux-serial&m=139749273432052&w=2

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