HAL_SITL: added --rtscts option to SITL

useful for radio testing

libraries/AP_HAL_SITL/SITL_State.h

@@ -51,6 +51,10 @@ public:
         return _base_port;
     }
 
+    bool use_rtscts(void) const {
+        return _use_rtscts;
+    }
+    
     // simulated airspeed, sonar and battery monitor
     uint16_t sonar_pin_value;    // pin 0
     uint16_t airspeed_pin_value; // pin 1
@@ -157,6 +161,8 @@ private:
 
     bool _synthetic_clock_mode;
 
+    bool _use_rtscts;
+    
     const char *_fdm_address;
 
     // delay buffer variables

libraries/AP_HAL_SITL/SITL_cmdline.cpp

@@ -129,6 +129,7 @@ void SITL_State::_parse_command_line(int argc, char * const argv[])
         CMDLINE_UARTE,
         CMDLINE_UARTF,
         CMDLINE_ADSB,
+        CMDLINE_RTSCTS,
         CMDLINE_DEFAULTS
     };
 
@@ -153,6 +154,7 @@ void SITL_State::_parse_command_line(int argc, char * const argv[])
         {"adsb",            false,  0, CMDLINE_ADSB},
         {"autotest-dir",    true,   0, CMDLINE_AUTOTESTDIR},
         {"defaults",        true,   0, CMDLINE_DEFAULTS},
+        {"rtscts",          false,  0, CMDLINE_RTSCTS},
         {0, false, 0, 0}
     };
 
@@ -205,6 +207,9 @@ void SITL_State::_parse_command_line(int argc, char * const argv[])
         case CMDLINE_ADSB:
             enable_ADSB = true;
             break;
+        case CMDLINE_RTSCTS:
+            _use_rtscts = true;
+            break;
         case CMDLINE_AUTOTESTDIR:
             autotest_dir = strdup(gopt.optarg);
             break;

libraries/AP_HAL_SITL/UARTDriver.cpp

@@ -324,6 +324,9 @@ void UARTDriver::_uart_start_connection(const char *path, uint32_t baudrate)
     t.c_oflag &= ~(OPOST | ONLCR);
     t.c_lflag &= ~(ISIG | ICANON | IEXTEN | ECHO | ECHOE | ECHOK | ECHOCTL | ECHOKE);
     t.c_cc[VMIN] = 0;
+    if (_sitlState->use_rtscts()) {
+        t.c_cflag |= CRTSCTS;
+    }
     tcsetattr(_fd, TCSANOW, &t);
 
     // set baudrate