zr-v4/libraries/AP_RangeFinder/AP_RangeFinder_MaxsonarSerialLV.cpp

/*
 * 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_SerialManager/AP_SerialManager.h>
#include <ctype.h>
#include "AP_RangeFinder_MaxsonarSerialLV.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::RangeFinder_State &_state,
                                                                 AP_RangeFinder_Params &_params,
                                                                 uint8_t serial_instance) :
    AP_RangeFinder_Backend(_state, _params)
{
    const AP_SerialManager &serial_manager = AP::serialmanager();
    uart = serial_manager.find_serial(AP_SerialManager::SerialProtocol_Rangefinder, serial_instance);
    if (uart != nullptr) {
        uart->begin(serial_manager.find_baudrate(AP_SerialManager::SerialProtocol_Rangefinder, serial_instance));
    }
}

/* 
   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(uint8_t serial_instance)
{
    return AP::serialmanager().find_serial(AP_SerialManager::SerialProtocol_Rangefinder, serial_instance) != nullptr;
}

// read - return last value measured by sensor
bool AP_RangeFinder_MaxsonarSerialLV::get_reading(uint16_t &reading_cm)
{
    if (uart == nullptr) {
        return false;
    }

#if 1
    float sum = 0;
    int16_t nbytes = uart->available();
    uint16_t count = 0;

    while (nbytes-- > 0) {
        char c = uart->read();
            // gcs().send_text(MAV_SEVERITY_INFO, "getc #%c",c);
            // gcs().send_text(MAV_SEVERITY_INFO, "getd #%d",(int)atoi(c);
            // gcs().send_text(MAV_SEVERITY_INFO, "getf #%f",(float)atof(c));

        if (c == '\r') {
            linebuf[linebuf_len] = 0;
            // sum += (int)atoi(linebuf);
            sum += (float)atof(linebuf);
            count++;
            linebuf_len = 0;
            // gcs().send_text(MAV_SEVERITY_INFO, "dist #%3.2f",sum);
        // } else if (isdigit() {
        } else {
            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 = 2.54f * sum / count;
    reading_cm = 100.0f * sum / count;

    return true;
#else 

    uint8_t frameOK = 0;   
    uint16_t Range  = 0;                                                //雷达实测距离
    int16_t  nbytes = uart->available(); 

    while ( nbytes-- > 0 ) {
        if( uart->read() == StartSequence ){                            //判断数据包帧头0xAA    
            string[0] = StartSequence;
            if( uart->read() == StartSequence ){                         //判断数据包帧头0xAA
                string[1] = StartSequence;
                for( int i = 2;i < 14;i++ ){                            //存储数据到数组      
                    string[i] = uart->read();
                }
                CheckSum = string[4]+string[5]+string[6]+string[7]+string[8]+string[9]+string[10];       
                if( string[11] == (CheckSum&0xFF)&&string[12] == EndSequence && string[13] == EndSequence ){         //按照协议对收到的数据进行校验  
                    frameOK = 1; 
                    Range = (string[6]*256+string[7]);                    //cm
                    // testdata = (string[8]*256+string[9]);    
                }
            }
        }
    }

    if (frameOK == 0) 
    {
       return false;
    }
    
    if(Range != 0)
    {
        reading_cm = Range;
    }
    return true;
#endif


}

/* 
   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
        state.last_reading_ms = AP_HAL::millis();
        update_status();
    } else if (AP_HAL::millis() - state.last_reading_ms > 500) {
        set_status(RangeFinder::RangeFinder_NoData);
    }
}