AP_RangeFinder: Added a new PX4 range finder and modified the RangeFinder parent class to support having multiple devices simultaneously

libraries/AP_RangeFinder/AP_RangeFinder.h

@@ -8,3 +8,4 @@
 #include "AP_RangeFinder_MaxsonarI2CXL.h"
 #include "AP_RangeFinder_PulsedLightLRF.h"
 #include "AP_RangeFinder_analog.h"
+#include "AP_RangeFinder_PX4.h"

libraries/AP_RangeFinder/AP_RangeFinder_PX4.cpp

@@ -0,0 +1,132 @@
+// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
+/*
+   This program 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 program 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.h>
+
+#if CONFIG_HAL_BOARD == HAL_BOARD_PX4
+#include "AP_RangeFinder_PX4.h"
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <unistd.h>
+
+#include <drivers/drv_range_finder.h>
+#include <drivers/drv_hrt.h>
+#include <stdio.h>
+#include <errno.h>
+
+extern const AP_HAL::HAL& hal;
+
+// Constructor ////////////////////////////////////////////////////////
+AP_RangeFinder_PX4::AP_RangeFinder_PX4(FilterInt16 *filter) :
+    RangeFinder(NULL, filter),
+    _num_instances(0){ }
+
+bool AP_RangeFinder_PX4::init(void)
+{
+	_range_fd[0] = open(RANGE_FINDER_DEVICE_PATH, O_RDONLY);
+	if (_range_fd[0] < 0) {
+        hal.console->printf("Unable to open " RANGE_FINDER_DEVICE_PATH "\n");
+        return false;
+	}
+
+	_range_fd[1] = open(RANGE_FINDER_DEVICE_PATH "1", O_RDONLY);
+	if (_range_fd[1] >= 0) {
+        _num_instances = 2;
+	} else {
+        _num_instances = 1;
+    }
+
+    for (uint8_t i=0; i<_num_instances; i++) {
+        // average over up to 20 samples
+        if (ioctl(_range_fd[i], SENSORIOCSQUEUEDEPTH, 20) != 0) {
+            hal.console->printf("Failed to setup range finder queue\n");
+            return false;                
+        }
+
+        _count[0] = 0;
+        _sum[i] = 0;
+        _healthy[i] = false;
+    }
+
+    // give the driver a chance to run, and gather one sample
+    hal.scheduler->delay(40);
+    accumulate();
+    if (_count[0] == 0) {
+        hal.console->printf("Failed initial range finder accumulate\n");        
+    }
+    return true;
+}
+
+bool AP_RangeFinder_PX4::take_reading(void)
+{
+    // try to accumulate one more sample, so we have the latest data
+    accumulate();
+
+    // consider the compass healthy if we got a reading in the last 0.2s
+    for (uint8_t i=0; i<_num_instances; i++) {
+        _healthy[i] = (hrt_absolute_time() - _last_timestamp[i] < 200000);
+    }
+
+    for (uint8_t i=0; i<_num_instances; i++) {
+        // avoid division by zero if we haven't received any range reports
+        if (_count[i] == 0) continue;
+
+        _sum[i] /= _count[i];
+        _sum[i] *= 100.00f;
+    
+        _distance[i] = _mode_filter->apply(_sum[i]);
+    
+        _sum[i] = 0;
+        _count[i] = 0;
+    }
+    
+    return _healthy[_get_primary()];
+}
+
+void AP_RangeFinder_PX4::accumulate(void)
+{
+    struct range_finder_report range_report;
+    for (uint8_t i=0; i<_num_instances; i++) {
+        while (::read(_range_fd[i], &range_report, sizeof(range_report)) == sizeof(range_report) &&
+               range_report.timestamp != _last_timestamp[i]) {
+            
+            // Only take valid readings
+            if (range_report.valid == 1) {
+               _sum[i] += range_report.distance;
+               _count[i]++;
+               _last_timestamp[i] = range_report.timestamp;
+            }
+        }
+    }
+}
+
+uint8_t AP_RangeFinder_PX4::_get_primary(void) const
+{
+    for (uint8_t i=0; i<_num_instances; i++) {
+        if (_healthy[i]) return i;
+    }    
+    return 0;
+}
+
+int16_t AP_RangeFinder_PX4::read()
+{
+    take_reading();
+    return _distance[_get_primary()];
+}
+
+#endif // CONFIG_HAL_BOARD

libraries/AP_RangeFinder/AP_RangeFinder_PX4.h

@@ -0,0 +1,49 @@
+// -*- tab-width: 4; Mode: C++; c-basic-offset: 4; indent-tabs-mode: nil -*-
+/*
+   This program 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 program 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/>.
+ */
+ 
+#ifndef AP_RangeFinder_PX4_H
+#define AP_RangeFinder_PX4_H
+
+#include "RangeFinder.h"
+
+class AP_RangeFinder_PX4 : public RangeFinder
+{
+public:
+    // constructor
+    AP_RangeFinder_PX4(FilterInt16 *filter);
+    
+    // initialize all the range finder devices
+    bool init(void);
+    
+    bool take_reading(void);
+    
+    void accumulate(void);
+    
+    // read value from primary sensor and return distance in cm
+    int16_t read();
+    
+    // return the number of compass instances
+    uint8_t get_count(void) const { return _num_instances; }
+private:
+    uint8_t _get_primary(void) const;
+    uint8_t _num_instances;
+    int _range_fd[RANGEFINDER_MAX_INSTANCES];
+    float _sum[RANGEFINDER_MAX_INSTANCES];
+    uint32_t _count[RANGEFINDER_MAX_INSTANCES];
+    uint64_t _last_timestamp[RANGEFINDER_MAX_INSTANCES];
+};
+
+#endif // AP_RangeFinder_PX4_H

libraries/AP_RangeFinder/RangeFinder.h

@@ -18,6 +18,16 @@
  * #define AP_RANGEFINDER_ORIENTATION_FRONT_LEFT      5,  5,  0
  */
 
+ /**
+   maximum number of range finder instances available on this platform. If more
+   than 1 then redundant sensors may be available
+ */
+#if CONFIG_HAL_BOARD == HAL_BOARD_PX4
+#define RANGEFINDER_MAX_INSTANCES 2
+#else
+#define RANGEFINDER_MAX_INSTANCES 1
+#endif
+ 
 class RangeFinder
 {
 protected:
@@ -25,6 +35,10 @@ protected:
         _analog_source(source),
         _mode_filter(filter) {
     }
+    
+    virtual uint8_t _get_primary(void) const { return 0; }
+    bool _healthy[RANGEFINDER_MAX_INSTANCES];
+    int16_t _distance[RANGEFINDER_MAX_INSTANCES];  // distance: in cm
 public:
     // distance: in cm
     int16_t  distance;
@@ -49,5 +63,16 @@ public:
 
     AP_HAL::AnalogSource*   _analog_source;
     FilterInt16 *           _mode_filter;
+    
+    /// Return the number of range finder instances
+    virtual uint8_t get_count(void) const { return 1; }
+
+    /// Return the current distance as a int16_t
+    int16_t get_distance(uint8_t i) const { return _distance[i]; }
+    int16_t get_distance(void) const { return get_distance(_get_primary()); }
+    
+    /// Return the health of a range finder
+    bool healthy(uint8_t i) const { return _healthy[i]; }
+    bool healthy(void) const { return healthy(_get_primary()); }
 };
 #endif // __RANGEFINDER_H__