add dtr control to serial::Serial constructor

typedef enum `dtrcontrol_t`  for specification in the constructor of `serial::Serial` and `serial::Serial::SerialImpl`.

add `dtrcontrol_t` parameter to `serial::Serial` and `serial::Serial::SerialImpl` constructors for both windows and unix. `serial::Serial` constructor parameter defaults to `dtr_disable`.

set dtr control in `serial::Serial::SerialImpl::reconfigurePort` with `ioctl`.

change parameter for `setDTR` to `dtrcontrol_t` in both `serial::Serial` and `serial::Serial::SerialImpl` for both windows and unix. Changed default in `serial::Serial::setDTR` to `dtr_enable`.

include/serial/impl/unix.h

@@ -70,7 +70,8 @@ public:
               bytesize_t bytesize,
               parity_t parity,
               stopbits_t stopbits,
-              flowcontrol_t flowcontrol);
+              flowcontrol_t flowcontrol,
+              dtrcontrol_t dtrcontrol);
 
   virtual ~SerialImpl ();
 
@@ -117,7 +118,7 @@ public:
   setRTS (bool level);
 
   void
-  setDTR (bool level);
+  setDTR (dtrcontrol_t dtrcontrol);
 
   bool
   waitForChange ();
@@ -207,6 +208,7 @@ private:
   bytesize_t bytesize_;       // Size of the bytes
   stopbits_t stopbits_;       // Stop Bits
   flowcontrol_t flowcontrol_; // Flow Control
+  dtrcontrol_t dtrcontrol_;   // Data Terminal Ready Control
 
   // Mutex used to lock the read functions
   pthread_mutex_t read_mutex;

include/serial/impl/win.h

@@ -59,7 +59,8 @@ public:
               bytesize_t bytesize,
               parity_t parity,
               stopbits_t stopbits,
-              flowcontrol_t flowcontrol);
+              flowcontrol_t flowcontrol,
+              dtrcontrol_t dtrcontrol);
 
   virtual ~SerialImpl ();
 
@@ -106,7 +107,7 @@ public:
   setRTS (bool level);
 
   void
-  setDTR (bool level);
+  setDTR (dtrcontrol_t dtrcontrol);
 
   bool
   waitForChange ();
@@ -193,6 +194,7 @@ private:
   bytesize_t bytesize_;       // Size of the bytes
   stopbits_t stopbits_;       // Stop Bits
   flowcontrol_t flowcontrol_; // Flow Control
+  dtrcontrol_t dtrcontrol_;   // Data Terminal Ready Control
 
   // Mutex used to lock the read functions
   HANDLE read_mutex;

include/serial/serial.h

@@ -89,6 +89,12 @@ typedef enum {
   flowcontrol_hardware
 } flowcontrol_t;
 
+typedef enum {
+    dtr_disable = 0,
+    dtr_enable = 1,
+    dtr_handshake = 2
+} dtrcontrol_t;
+
 /*!
  * Structure for setting the timeout of the serial port, times are
  * in milliseconds.
@@ -183,7 +189,8 @@ public:
           bytesize_t bytesize = eightbits,
           parity_t parity = parity_none,
           stopbits_t stopbits = stopbits_one,
-          flowcontrol_t flowcontrol = flowcontrol_none);
+          flowcontrol_t flowcontrol = flowcontrol_none,
+          dtrcontrol_t dtr = dtr_disable);
 
   /*! Destructor */
   virtual ~Serial ();
@@ -612,7 +619,7 @@ public:
 
   /*! Set the DTR handshaking line to the given level.  Defaults to true. */
   void
-  setDTR (bool level = true);
+  setDTR (dtrcontrol_t dtrcontrol = dtr_enable);
 
   /*!
    * Blocks until CTS, DSR, RI, CD changes or something interrupts it.

src/impl/unix.cc

@@ -108,10 +108,12 @@ timespec_from_ms (const uint32_t millis)
 Serial::SerialImpl::SerialImpl (const string &port, unsigned long baudrate,
                                 bytesize_t bytesize,
                                 parity_t parity, stopbits_t stopbits,
-                                flowcontrol_t flowcontrol)
+                                flowcontrol_t flowcontrol,
+                                dtrcontrol_t dtrcontrol)
   : port_ (port), fd_ (-1), is_open_ (false), xonxoff_ (false), rtscts_ (false),
     baudrate_ (baudrate), parity_ (parity),
-    bytesize_ (bytesize), stopbits_ (stopbits), flowcontrol_ (flowcontrol)
+    bytesize_ (bytesize), stopbits_ (stopbits),
+    flowcontrol_ (flowcontrol), dtrcontrol_ (dtrcontrol)
 {
   pthread_mutex_init(&this->read_mutex, NULL);
   pthread_mutex_init(&this->write_mutex, NULL);
@@ -376,6 +378,13 @@ Serial::SerialImpl::reconfigurePort ()
     xonxoff_ = false;
     rtscts_ = true;
   }
+  // setup dtr control
+  int dtr_flag = TIOCM_DTR;
+  if (dtrcontrol_ == dtr_enable) {
+    ioctl(fd_, TIOCMBIS, &dtr_flag);
+  } else if (dtrcontrol_ == dtr_disable) {
+    ioctl(fd_, TIOCMBIC, &dtr_flag);
+  }
   // xonxoff
 #ifdef IXANY
   if (xonxoff_)
@@ -893,7 +902,7 @@ Serial::SerialImpl::setRTS (bool level)
 }
 
 void
-Serial::SerialImpl::setDTR (bool level)
+Serial::SerialImpl::setDTR (dtrcontrol_t dtrcontrol)
 {
   if (is_open_ == false) {
     throw PortNotOpenedException ("Serial::setDTR");
@@ -901,14 +910,14 @@ Serial::SerialImpl::setDTR (bool level)
 
   int command = TIOCM_DTR;
 
-  if (level) {
+  if (dtrcontrol == dtr_enable) {
     if (-1 == ioctl (fd_, TIOCMBIS, &command))
     {
       stringstream ss;
       ss << "setDTR failed on a call to ioctl(TIOCMBIS): " << errno << " " << strerror(errno);
       throw(SerialException(ss.str().c_str()));
     }
-  } else {
+  } else if (dtrcontrol == dtr_disable) {
     if (-1 == ioctl (fd_, TIOCMBIC, &command))
     {
       stringstream ss;

src/impl/win.cc

@@ -34,10 +34,12 @@ _prefix_port_if_needed(const wstring &input)
 Serial::SerialImpl::SerialImpl (const string &port, unsigned long baudrate,
                                 bytesize_t bytesize,
                                 parity_t parity, stopbits_t stopbits,
-                                flowcontrol_t flowcontrol)
+                                flowcontrol_t flowcontrol,
+                                dtrcontrol_t dtrcontrol)
   : port_ (port.begin(), port.end()), fd_ (INVALID_HANDLE_VALUE), is_open_ (false),
     baudrate_ (baudrate), parity_ (parity),
-    bytesize_ (bytesize), stopbits_ (stopbits), flowcontrol_ (flowcontrol)
+    bytesize_ (bytesize), stopbits_ (stopbits),
+    flowcontrol_ (flowcontrol), dtrcontrol_ (dtrcontrol)
 {
   if (port_.empty () == false)
     open ();
@@ -256,6 +258,13 @@ Serial::SerialImpl::reconfigurePort ()
     dcbSerialParams.fInX = false;
   }
 
+  // setup dtr control
+  if (dtrcontrol_ == dtr_enable) {
+    dcbSerialParams.fDtrControl = DTR_CONTROL_ENABLE;
+  } else if (dtrcontrol_ == dtr_disable) {
+    dcbSerialParams.fDtrControl = DTR_CONTROL_DISABLE;
+  }
+
   // activate settings
   if (!SetCommState(fd_, &dcbSerialParams)){
     CloseHandle(fd_);
@@ -519,14 +528,14 @@ Serial::SerialImpl::setRTS (bool level)
 }
 
 void
-Serial::SerialImpl::setDTR (bool level)
+Serial::SerialImpl::setDTR (dtrcontrol_t dtrcontrol)
 {
   if (is_open_ == false) {
     throw PortNotOpenedException ("Serial::setDTR");
   }
-  if (level) {
+  if (dtrcontrol == dtr_enable) {
     EscapeCommFunction (fd_, SETDTR);
-  } else {
+  } else if (dtrcontrol == dtr_disable) {
     EscapeCommFunction (fd_, CLRDTR);
   }
 }

src/serial.cc

@@ -65,9 +65,9 @@ private:
 
 Serial::Serial (const string &port, uint32_t baudrate, serial::Timeout timeout,
                 bytesize_t bytesize, parity_t parity, stopbits_t stopbits,
-                flowcontrol_t flowcontrol)
+                flowcontrol_t flowcontrol, dtrcontrol_t dtrcontrol)
  : pimpl_(new SerialImpl (port, baudrate, bytesize, parity,
-                                           stopbits, flowcontrol))
+                                           stopbits, flowcontrol, dtrcontrol))
 {
   pimpl_->setTimeout(timeout);
 }
@@ -401,9 +401,9 @@ void Serial::setRTS (bool level)
   pimpl_->setRTS (level);
 }
 
-void Serial::setDTR (bool level)
+void Serial::setDTR (dtrcontrol_t dtrcontrol)
 {
-  pimpl_->setDTR (level);
+  pimpl_->setDTR (dtrcontrol);
 }
 
 bool Serial::waitForChange()