AP_RangeFinder: support MaxBotix Serial rangefinders

This has been tested with LV-MaxSonar®-EZ1 MB1010

libraries/AP_RangeFinder/AP_RangeFinder_MaxsonarSerialLV.cpp

@@ -0,0 +1,111 @@
+// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
+/*
+ * Copyright (C) 2016  Intel Corporation. All rights reserved.
+ *
+ * This file is free software: you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License as published by the
+ * Free Software Foundation, either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This file is distributed in the hope that it will be useful, but
+ * WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
+ * See the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with this program.  If not, see <http://www.gnu.org/licenses/>.
+ */
+
+#include <AP_HAL/AP_HAL.h>
+#include "AP_RangeFinder_MaxsonarSerialLV.h"
+#include <AP_SerialManager/AP_SerialManager.h>
+#include <ctype.h>
+
+#define MAXSONAR_SERIAL_LV_BAUD_RATE 9600
+
+extern const AP_HAL::HAL& hal;
+
+/* 
+   The constructor also initialises the rangefinder. Note that this
+   constructor is not called until detect() returns true, so we
+   already know that we should setup the rangefinder
+*/
+AP_RangeFinder_MaxsonarSerialLV::AP_RangeFinder_MaxsonarSerialLV(RangeFinder &_ranger, uint8_t instance,
+                                                                 RangeFinder::RangeFinder_State &_state,
+                                                                 AP_SerialManager &serial_manager) :
+    AP_RangeFinder_Backend(_ranger, instance, _state)
+{
+    uart = serial_manager.find_serial(AP_SerialManager::SerialProtocol_Lidar, 0);
+    if (uart != nullptr) {
+        uart->begin(serial_manager.find_baudrate(AP_SerialManager::SerialProtocol_Lidar, 0));
+    }
+}
+
+/* 
+   detect if a MaxSonar rangefinder is connected. We'll detect by
+   trying to take a reading on Serial. If we get a result the sensor is
+   there.
+*/
+bool AP_RangeFinder_MaxsonarSerialLV::detect(RangeFinder &_ranger, uint8_t instance, AP_SerialManager &serial_manager)
+{
+    return serial_manager.find_serial(AP_SerialManager::SerialProtocol_Lidar, 0) != nullptr;
+}
+
+// read - return last value measured by sensor
+bool AP_RangeFinder_MaxsonarSerialLV::get_reading(uint16_t &reading_cm)
+{
+    if (uart == nullptr) {
+        return false;
+    }
+
+    int32_t sum = 0;
+    int16_t nbytes = uart->available();
+    uint16_t count = 0;
+
+    /* MaxSonarSeriaLV might need a manual reconection */
+    if (nbytes == 0) {
+        uart->end();
+        uart->begin(MAXSONAR_SERIAL_LV_BAUD_RATE);
+        nbytes = uart->available();
+    }
+
+    while (nbytes-- > 0) {
+        char c = uart->read();
+        if (c == '\r') {
+            linebuf[linebuf_len] = 0;
+            sum += (int)atoi(linebuf);
+            count++;
+            linebuf_len = 0;
+        } else if (isdigit(c)) {
+            linebuf[linebuf_len++] = c;
+            if (linebuf_len == sizeof(linebuf)) {
+                // too long, discard the line
+                linebuf_len = 0;
+            }
+        }
+    }
+
+
+    if (count == 0) {
+        return false;
+    }
+
+    // This sonar gives the metrics in inches, so we have to transform this to centimeters
+    reading_cm = 2.54 * sum / count;
+
+    return true;
+}
+
+/* 
+   update the state of the sensor
+*/
+void AP_RangeFinder_MaxsonarSerialLV::update(void)
+{
+    if (get_reading(state.distance_cm)) {
+        // update range_valid state based on distance measured
+        last_reading_ms = AP_HAL::millis();
+        update_status();
+    } else if (AP_HAL::millis() - last_reading_ms > 500) {
+        set_status(RangeFinder::RangeFinder_NoData);
+    }
+}

libraries/AP_RangeFinder/AP_RangeFinder_MaxsonarSerialLV.h

@@ -0,0 +1,29 @@
+// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
+#pragma once
+
+#include "RangeFinder.h"
+#include "RangeFinder_Backend.h"
+
+class AP_RangeFinder_MaxsonarSerialLV : public AP_RangeFinder_Backend
+{
+
+public:
+    // constructor
+    AP_RangeFinder_MaxsonarSerialLV(RangeFinder &ranger, uint8_t instance, RangeFinder::RangeFinder_State &_state,
+                                   AP_SerialManager &serial_manager);
+
+    // static detection function
+    static bool detect(RangeFinder &ranger, uint8_t instance, AP_SerialManager &serial_manager);
+
+    // update state
+    void update(void);
+
+private:
+    // get a reading
+    bool get_reading(uint16_t &reading_cm);
+
+    AP_HAL::UARTDriver *uart = nullptr;
+    uint32_t last_reading_ms = 0;
+    char linebuf[10];
+    uint8_t linebuf_len = 0;
+};

libraries/AP_RangeFinder/RangeFinder.cpp

@@ -17,6 +17,7 @@
 #include "AP_RangeFinder_analog.h"
 #include "AP_RangeFinder_PulsedLightLRF.h"
 #include "AP_RangeFinder_MaxsonarI2CXL.h"
+#include "AP_RangeFinder_MaxsonarSerialLV.h"
 #include "AP_RangeFinder_PX4.h"
 #include "AP_RangeFinder_PX4_PWM.h"
 #include "AP_RangeFinder_BBB_PRU.h"
@@ -35,7 +36,7 @@ const AP_Param::GroupInfo RangeFinder::var_info[] = {
     // @Param: _TYPE
     // @DisplayName: Rangefinder type
     // @Description: What type of rangefinder device that is connected
-    // @Values: 0:None,1:Analog,2:MaxbotixI2C,3:PulsedLightI2C,4:PX4-I2C,5:PX4-PWM,6:BBB-PRU,7:LightWareI2C,8:LightWareSerial,9:Bebop,10:MAVLink,12:LeddarOne
+    // @Values: 0:None,1:Analog,2:MaxbotixI2C,3:PulsedLightI2C,4:PX4-I2C,5:PX4-PWM,6:BBB-PRU,7:LightWareI2C,8:LightWareSerial,9:Bebop,10:MAVLink,12:LeddarOne,13:MaxbotixSerial
     // @User: Standard
     AP_GROUPINFO("_TYPE",    0, RangeFinder, _type[0], 0),
 
@@ -155,7 +156,7 @@ const AP_Param::GroupInfo RangeFinder::var_info[] = {
     // @Param: 2_TYPE
     // @DisplayName: Second Rangefinder type
     // @Description: What type of rangefinder device that is connected
-    // @Values: 0:None,1:Analog,2:MaxbotixI2C,3:PulsedLightI2C,4:PX4-I2C,5:PX4-PWM,6:BBB-PRU,7:LightWareI2C,8:LightWareSerial,9:Bebop,10:MAVLink,12:LeddarOne
+    // @Values: 0:None,1:Analog,2:MaxbotixI2C,3:PulsedLightI2C,4:PX4-I2C,5:PX4-PWM,6:BBB-PRU,7:LightWareI2C,8:LightWareSerial,9:Bebop,10:MAVLink,12:LeddarOne,13:MaxbotixSerial
     // @User: Advanced
     AP_GROUPINFO("2_TYPE",    12, RangeFinder, _type[1], 0),
 
@@ -270,7 +271,7 @@ const AP_Param::GroupInfo RangeFinder::var_info[] = {
     // @Param: 3_TYPE
     // @DisplayName: Third Rangefinder type
     // @Description: What type of rangefinder device that is connected
-    // @Values: 0:None,1:Analog,2:APM2-MaxbotixI2C,3:APM2-PulsedLightI2C,4:PX4-I2C,5:PX4-PWM,6:BBB-PRU,7:LightWareI2C,8:LightWareSerial,9:Bebop,10:MAVLink,12:LeddarOne
+    // @Values: 0:None,1:Analog,2:APM2-MaxbotixI2C,3:APM2-PulsedLightI2C,4:PX4-I2C,5:PX4-PWM,6:BBB-PRU,7:LightWareI2C,8:LightWareSerial,9:Bebop,10:MAVLink,12:LeddarOne,13:MaxbotixSerial
     // @User: Advanced
     AP_GROUPINFO("3_TYPE",    25, RangeFinder, _type[2], 0),
 
@@ -385,7 +386,7 @@ const AP_Param::GroupInfo RangeFinder::var_info[] = {
     // @Param: 4_TYPE
     // @DisplayName: Fourth Rangefinder type
     // @Description: What type of rangefinder device that is connected
-    // @Values: 0:None,1:Analog,2:APM2-MaxbotixI2C,3:APM2-PulsedLightI2C,4:PX4-I2C,5:PX4-PWM,6:BBB-PRU,7:LightWareI2C,8:LightWareSerial,9:Bebop,10:MAVLink,12:LeddarOne
+    // @Values: 0:None,1:Analog,2:APM2-MaxbotixI2C,3:APM2-PulsedLightI2C,4:PX4-I2C,5:PX4-PWM,6:BBB-PRU,7:LightWareI2C,8:LightWareSerial,9:Bebop,10:MAVLink,12:LeddarOne,13:MaxbotixSerial
     // @User: Advanced
     AP_GROUPINFO("4_TYPE",    37, RangeFinder, _type[3], 0),
 
@@ -662,6 +663,13 @@ void RangeFinder::detect_instance(uint8_t instance)
             return;
         }
     }
+    if (type == RangeFinder_TYPE_MBSER) {
+        if (AP_RangeFinder_MaxsonarSerialLV::detect(*this, instance, serial_manager)) {
+            state[instance].instance = instance;
+            drivers[instance] = new AP_RangeFinder_MaxsonarSerialLV(*this, instance, state[instance], serial_manager);
+            return;
+        }
+    } 
     if (type == RangeFinder_TYPE_ANALOG) {
         // note that analog must be the last to be checked, as it will
         // always come back as present if the pin is valid

libraries/AP_RangeFinder/RangeFinder.h

@@ -49,7 +49,8 @@ public:
         RangeFinder_TYPE_BEBOP  = 9,
         RangeFinder_TYPE_MAVLink = 10,
         RangeFinder_TYPE_ULANDING= 11,
-        RangeFinder_TYPE_LEDDARONE = 12
+        RangeFinder_TYPE_LEDDARONE = 12,
+        RangeFinder_TYPE_MBSER  = 13
     };
 
     enum RangeFinder_Function {