CSickLaserSerial.cpp

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/* +------------------------------------------------------------------------+
   |                     Mobile Robot Programming Toolkit (MRPT)            |
   |                          http://www.mrpt.org/                          |
   |                                                                        |
   | Copyright (c) 2005-2018, Individual contributors, see AUTHORS file     |
   | See: http://www.mrpt.org/Authors - All rights reserved.                |
   | Released under BSD License. See details in http://www.mrpt.org/License |
   +------------------------------------------------------------------------+ */
 
// This file contains portions of code from sicklms200.cc from the Player/Stage
// project.
 
#include "hwdrivers-precomp.h"  // Precompiled headers
 
#include <mrpt/system/crc.h>
#include <mrpt/system/CTicTac.h>
#include <mrpt/system/os.h>
 
#include <mrpt/hwdrivers/CSickLaserSerial.h>
 
IMPLEMENTS_GENERIC_SENSOR(CSickLaserSerial, mrpt::hwdrivers)
 
#define RET_ERROR(msg)                                                   \
        {                                                                    \
                cout << "[" << __CURRENT_FUNCTION_NAME__ << "] " << msg << endl; \
                return false;                                                    \
        }
 
using namespace std;
using namespace mrpt;
using namespace mrpt::comms;
using namespace mrpt::obs;
using namespace mrpt::poses;
using namespace mrpt::math;
using namespace mrpt::hwdrivers;
using namespace mrpt::system;
 
int CSickLaserSerial::CRC16_GEN_POL = 0x8005;
 
/*-------------------------------------------------------------
                                                CSickLaserSerial
-------------------------------------------------------------*/
CSickLaserSerial::CSickLaserSerial()
        : m_mm_mode(false),
          m_scans_FOV(180),
          m_scans_res(50),
          m_com_port(),
          m_mySerialPort(nullptr),
          m_com_baudRate(38400),
          m_nTries_connect(1),
          m_nTries_current(0),
          m_skip_laser_config(false)
{
        m_sensorLabel = "SICKLMS";
        memset(m_received_frame_buffer, 0, sizeof(m_received_frame_buffer));
}
 
/*-------------------------------------------------------------
                                                ~CSickLaserSerial
-------------------------------------------------------------*/
CSickLaserSerial::~CSickLaserSerial()
{
        if (m_stream)
        {
                try
                {
                        if (!m_skip_laser_config)
                        {
                                LMS_endContinuousMode();
                        }
                }
                catch (...)
                {
                }
        }
 
        if (m_mySerialPort)
        {
                delete m_mySerialPort;
                m_mySerialPort = nullptr;
        }
}
 
/*-------------------------------------------------------------
                                                doProcessSimple
-------------------------------------------------------------*/
void CSickLaserSerial::doProcessSimple(
        bool& outThereIsObservation,
        mrpt::obs::CObservation2DRangeScan& outObservation, bool& hardwareError)
{
        outThereIsObservation = false;
        hardwareError = false;
 
        if (!tryToOpenComms())
        {
                hardwareError = true;
                return;
        }
 
        vector<float> ranges;
        unsigned char LMS_stat;
        bool is_mm_mode;
 
        m_state = ssWorking;
 
        // Wait for a scan:
        if (!waitContinuousSampleFrame(ranges, LMS_stat, is_mm_mode)) return;
 
        // Yes, we have a new scan:
 
        // -----------------------------------------------
        //   Extract the observation:
        // -----------------------------------------------
        outObservation.timestamp = mrpt::system::now();
 
        outObservation.sensorLabel = m_sensorLabel;  // Set label
 
        // Extract the timestamp of the sensor:
 
        // And the scan ranges:
        outObservation.rightToLeft = true;
        outObservation.aperture = M_PIf;
        outObservation.maxRange = is_mm_mode ? 32.7 : 81.0;
        outObservation.stdError = 0.003f;
        outObservation.sensorPose = mrpt::poses::CPose3D(m_sensorPose);
 
        outObservation.resizeScan(ranges.size());
 
        for (size_t i = 0; i < ranges.size(); i++)
        {
                outObservation.setScanRange(i, ranges[i]);
                outObservation.setScanRangeValidity(
                        i, (outObservation.scan[i] <= outObservation.maxRange));
        }
 
        // Do filter:
        C2DRangeFinderAbstract::filterByExclusionAreas(outObservation);
        C2DRangeFinderAbstract::filterByExclusionAngles(outObservation);
        // Do show preview:
        C2DRangeFinderAbstract::processPreview(outObservation);
 
        outThereIsObservation = true;
}
 
/*-------------------------------------------------------------
                                                loadConfig_sensorSpecific
-------------------------------------------------------------*/
void CSickLaserSerial::loadConfig_sensorSpecific(
        const mrpt::config::CConfigFileBase& configSource,
        const std::string& iniSection)
{
        m_sensorPose = TPose3D(
                configSource.read_float(iniSection, "pose_x", 0),
                configSource.read_float(iniSection, "pose_y", 0),
                configSource.read_float(iniSection, "pose_z", 0),
                DEG2RAD(configSource.read_float(iniSection, "pose_yaw", 0)),
                DEG2RAD(configSource.read_float(iniSection, "pose_pitch", 0)),
                DEG2RAD(configSource.read_float(iniSection, "pose_roll", 0)));
 
        m_mm_mode = configSource.read_bool(iniSection, "mm_mode", m_mm_mode);
 
#ifdef _WIN32
        m_com_port =
                configSource.read_string(iniSection, "COM_port_WIN", m_com_port, true);
#else
        m_com_port =
                configSource.read_string(iniSection, "COM_port_LIN", m_com_port, true);
#endif
 
        m_com_baudRate =
                configSource.read_int(iniSection, "COM_baudRate", m_com_baudRate);
        m_nTries_connect =
                configSource.read_int(iniSection, "nTries_connect", m_nTries_connect);
 
        m_scans_FOV = configSource.read_int(iniSection, "FOV", m_scans_FOV);
        m_scans_res = configSource.read_int(iniSection, "resolution", m_scans_res);
 
        m_skip_laser_config = configSource.read_bool(
                iniSection, "skip_laser_config", m_skip_laser_config);
 
        // Parent options:
        C2DRangeFinderAbstract::loadCommonParams(configSource, iniSection);
}
 
/*-------------------------------------------------------------
                                                turnOn
-------------------------------------------------------------*/
bool CSickLaserSerial::turnOn() { return true; }
/*-------------------------------------------------------------
                                                turnOff
-------------------------------------------------------------*/
bool CSickLaserSerial::turnOff() { return true; }
/*-------------------------------------------------------------
 Tries to open the com port and setup
 all the LMS protocol. Returns true if OK or already open.
-------------------------------------------------------------*/
bool CSickLaserSerial::tryToOpenComms(std::string* err_msg)
{
        if (err_msg) *err_msg = "";
        try
        {
                if (!m_stream)
                {
                        ASSERT_(m_mySerialPort == nullptr);
 
                        // There is no COMMS port open yet...
                        if (!m_com_port.empty())
                        {
                                // Create the port myself:
                                m_mySerialPort = new CSerialPort();
                                m_stream = m_mySerialPort;
                        }
                        else
                                throw std::logic_error(
                                        "ERROR: No serial port attached with bindIO, neither it "
                                        "set with 'setSerialPort'");
                }
 
                // We assure now we have a stream... try to open it, if it's not done
                // yet.
                bool just_open = false;
                CSerialPort* COM = dynamic_cast<CSerialPort*>(m_stream);
                if (COM != nullptr)
                {
                        if (!COM->isOpen())
                        {
                                // Try to open it now:
                                COM->setSerialPortName(m_com_port);
                                COM->open();  // will raise an exception on error.
 
                                // Set basic params:
                                COM->setConfig(9600);
                                COM->setTimeouts(100, 0, 10, 0, 50);
 
                                just_open = true;
                        }
                }
 
                // It seems the port was open and working so we are done here.
                if (!just_open) return true;
 
                // ==================================================================
                // Otherwise, it was just opened now, we must send the
                //  ** initialization commands **
                // and put the laser in continuous measuring mode:
                // ==================================================================
                if (!m_skip_laser_config)
                {
                        if (!LMS_setupSerialComms()) RET_ERROR("error");
 
                        bool res;
                        for (int nTry = 0; nTry < 4; nTry++)
                                if (true == (res = LMS_sendMeasuringMode_cm_mm())) break;
 
                        if (!res) return false;
 
                        for (int nTry = 0; nTry < 4; nTry++)
                                if (true == (res = LMS_startContinuousMode())) break;
 
                        return res;
                }
                else
                {
                        // Skip setup:
                        return true;
                }
        }
        catch (std::exception& e)
        {
                std::string s = "[CSickLaserSerial] Error trying to open SICK at port ";
                s += e.what();
                if (err_msg) *err_msg = s;
                MRPT_LOG_ERROR(s);
                return false;
        }
}
 
/*-------------------------------------------------------------
                                        waitContinuousSampleFrame
-------------------------------------------------------------*/
bool CSickLaserSerial::waitContinuousSampleFrame(
        vector<float>& out_ranges_meters, unsigned char& LMS_status,
        bool& is_mm_mode)
{
        CSerialPort* COM = dynamic_cast<CSerialPort*>(m_stream);
        ASSERTMSG_(COM != nullptr, "No I/O channel bound to this object");
 
        size_t nRead, nBytesToRead;
        size_t nFrameBytes = 0;
        size_t lengthField;
        unsigned char buf[2000];
        buf[2] = buf[3] = buf[4] = 0;
 
        while (nFrameBytes < (lengthField = (6 + (buf[2] | (buf[3] << 8)))))
        {
                if (lengthField > 800)
                {
                        cout << "#";
                        nFrameBytes = 0;  // No es cabecera de trama correcta
                        buf[2] = buf[3] = 0;
                }
 
                if (nFrameBytes < 4)
                        nBytesToRead = 1;
                else
                        nBytesToRead = (lengthField)-nFrameBytes;
 
                try
                {
                        nRead = COM->Read(buf + nFrameBytes, nBytesToRead);
                }
                catch (std::exception& e)
                {
                        // Disconnected?
                        MRPT_LOG_ERROR_FMT(
                                "[CSickLaserSerial::waitContinuousSampleFrame] Disconnecting "
                                "due to comms error: %s\n",
                                e.what());
                        // m_usbConnection->Close();
                        return false;
                }
 
                if (!nRead && !nFrameBytes) return false;
 
                if (nRead < nBytesToRead) std::this_thread::sleep_for(1ms);
 
                // Lectura OK:
                // Era la primera?
                if (nFrameBytes > 1 || (!nFrameBytes && buf[0] == 0x02) ||
                        (nFrameBytes == 1 && buf[1] == 0x80))
                {
                        nFrameBytes += nRead;
                }
                else
                {
                        nFrameBytes = 0;  // No es cabecera de trama correcta
                        buf[2] = buf[3] = 0;
                        // cerr << "."; //"[CSickLaserSerial] Skipping non-header..." <<
                        // endl;
                }
        }
 
        // Frame received
        // --------------------------------------------------------------------------
        // | STX | ADDR | L1 | L2 | COM | INF1 | INF2 | DATA    | STA | CRC1 | CRC2
        // |
        // --------------------------------------------------------------------------
 
        // Trama completa:
        //  Checkear que el byte de comando es 0xB0:
        if (buf[4] != 0xB0) return false;
 
        // GET FRAME INFO
        int info = buf[5] | (buf[6] << 8);  // Little Endian
        int n_points = info & 0x01FF;
        is_mm_mode = 0 != ((info & 0xC000) >> 14);  // 0x00: cm 0x01: mm
 
        out_ranges_meters.resize(n_points);
 
        // Copiar rangos:
        short mask = is_mm_mode ? 0x7FFF : 0x1FFF;
        float meters_scale = is_mm_mode ? 0.001f : 0.01f;
 
        for (int i = 0; i < n_points; i++)
                out_ranges_meters[i] =
                        ((buf[7 + i * 2] | (buf[8 + i * 2] << 8)) & mask) * meters_scale;
 
        // Status
        LMS_status = buf[lengthField - 3];
 
        // CRC:
        uint16_t CRC =
                mrpt::system::compute_CRC16(buf, lengthField - 2, CRC16_GEN_POL);
        uint16_t CRC_packet = buf[lengthField - 2] | (buf[lengthField - 1] << 8);
        if (CRC_packet != CRC)
        {
                cerr << format(
                                        "[CSickLaserSerial::waitContinuousSampleFrame] bad CRC "
                                        "len=%u nptns=%u: %i != %i",
                                        unsigned(lengthField), unsigned(n_points), CRC_packet, CRC)
                         << endl;
                return false;  // Bad CRC
        }
 
        // All OK
        return true;
}
 
/*-------------------------------------------------------------
                                                initialize
-------------------------------------------------------------*/
void CSickLaserSerial::initialize()
{
        string err_str;
        memset(m_received_frame_buffer, 0, sizeof(m_received_frame_buffer));
        if (!tryToOpenComms(&err_str))
        {
                cerr << err_str << endl;
                throw std::logic_error(err_str);
        }
}
 
/*-----------------------------------------------------------------
        Assures laser is connected and operating at 38400, in
         its case returns true.
  -----------------------------------------------------------------*/
bool CSickLaserSerial::LMS_setupSerialComms()
{
        ASSERT_(
                m_com_baudRate == 9600 || m_com_baudRate == 38400 ||
                m_com_baudRate == 500000);
 
        CSerialPort* COM = dynamic_cast<CSerialPort*>(m_stream);
        if (COM == nullptr) return true;
 
        int detected_rate = 0;
        for (size_t reps = 0; !detected_rate && reps < m_nTries_connect; reps++)
        {
                m_nTries_current = reps;
 
                int rates[] = {0, 9600, 38400, 500000};
 
                // Try first the desired rate to speed up the process, just in case
                //  the laser is already setup from a previous run:
                rates[0] = m_com_baudRate;
 
                detected_rate = 0;
 
                for (size_t i = 0;
                         !detected_rate && i < sizeof(rates) / sizeof(rates[0]); i++)
                {
                        // Are we already receiving at 500k?
                        // ------------------------------------------------
                        COM->setConfig(rates[i]);
                        if (m_verbose)
                                printf(
                                        "[CSickLaserSerial] Testing if the scanner is "
                                        "set to %i bauds...\n",
                                        rates[i]);
 
                        LMS_endContinuousMode();  // Stop continuous mode.
                        std::this_thread::sleep_for(100ms);
                        COM->purgeBuffers();
 
                        for (int nTry = 0; nTry < 4 && !detected_rate; nTry++)
                        {
                                COM->purgeBuffers();
                                // Ask for the laser status at the current rate:
                                if (LMS_statusQuery())
                                {
                                        detected_rate = rates[i];
                                        break;
                                }
                                std::this_thread::sleep_for(20ms);
                        }  // for tries
                        // There is no link, or the baudrate is wrong...
                }
 
                // Try again in a while:
                if (!detected_rate && reps != (m_nTries_connect - 1))
                        std::this_thread::sleep_for(5000ms);
        }
 
        // Are we connected at the right rate?
        if (detected_rate == m_com_baudRate) return true;
 
        // Switch to the desired rate now
        if (!this->LMS_setupBaudrate(m_com_baudRate)) RET_ERROR("error");
 
        // Check response is OK:
        if (!(m_received_frame_buffer[2] == 0x03 &&
                  m_received_frame_buffer[4] == 0xA0 &&
                  m_received_frame_buffer[6] == 0x10))
                return false;
 
        COM->setConfig(m_com_baudRate);
        COM->purgeBuffers();
 
        // Wait...
        std::this_thread::sleep_for(500ms);
 
        // And check comms at the new baud rate:
        return LMS_statusQuery();
}
 
/*-----------------------------------------------------------------
 Query to LMS a baudrate change command.
   Returns true if response is read ok.
  -----------------------------------------------------------------*/
bool CSickLaserSerial::LMS_setupBaudrate(int baud)
{
        ASSERT_(m_stream);
        if (m_verbose)
                printf("[CSickLaserSerial::LMS_setupBaudrate] rate=%i\n", baud);
 
        uint8_t cmd[4];
        cmd[0] = 0x20;
        switch (baud)
        {
                case 9600:
                        cmd[1] = 0x42;
                        break;
                case 19200:
                        cmd[1] = 0x41;
                        break;
                case 38400:
                        cmd[1] = 0x40;
                        break;
                case 500000:
                        cmd[1] = 0x48;
                        break;
                default:
                        THROW_EXCEPTION("Invalid baud rate value");
        }
 
        uint16_t cmd_len = 2;
 
        if (!SendCommandToSICK(cmd, cmd_len)) return false;
        return LMS_waitIncomingFrame(500);
}
 
/*-----------------------------------------------------------------
  Query to LMS a status query.
   Returns true if response is read ok.
  -----------------------------------------------------------------*/
bool CSickLaserSerial::LMS_statusQuery()
{
        ASSERT_(m_stream);
 
        uint8_t cmd[1];
        cmd[0] = 0x31;
        uint16_t cmd_len = 1;
 
        if (!SendCommandToSICK(cmd, cmd_len)) return false;
        return LMS_waitIncomingFrame(500);
}
 
// Returns false if timeout
bool CSickLaserSerial::LMS_waitACK(uint16_t timeout_ms)
{
        CSerialPort* COM = dynamic_cast<CSerialPort*>(m_stream);
        ASSERT_(COM);
 
        uint8_t b = 0;
        CTicTac tictac;
        tictac.Tic();
 
        do
        {
                if (COM->Read(&b, 1))
                {  // Byte rx:
                        if (b == 0x06) return true;
                }
        } while (tictac.Tac() < timeout_ms * 1e-3);
 
        if (b == 0x15)
                RET_ERROR(format("NACK received."))
        else if (b != 0)
                RET_ERROR(format("Unexpected code received: 0x%02X", b))
        else
                return false;  // RET_ERROR("Timeout")
}
 
// Returns false if timeout
bool CSickLaserSerial::LMS_waitIncomingFrame(uint16_t timeout)
{
        CSerialPort* COM = dynamic_cast<CSerialPort*>(m_stream);
        ASSERT_(COM);
 
        uint8_t b;
        unsigned int nBytes = 0;
 
        CTicTac tictac;
        tictac.Tic();
        const double maxTime = timeout * 1e-3;
 
        while (nBytes < 6 ||
                   (nBytes < (6U + m_received_frame_buffer[2] +
                                          (uint16_t)(m_received_frame_buffer[3] << 8))))
        {
                if (COM->Read(&b, 1))
                {
                        // First byte must be STX:
                        if (nBytes > 1 || (!nBytes && b == 0x02) ||
                                (nBytes == 1 && b == 0x80))
                        {
                                // Store in frame:
                                m_received_frame_buffer[nBytes] = b;
                                nBytes++;
                                if (m_verbose)
                                {
                                        printf("[CSickLaserSerial::Receive] RX: %02X\n", b);
                                }
                        }
                }
                if (tictac.Tac() >= maxTime) return false;  // Timeout
        }
 
        const uint16_t lengthField =
                m_received_frame_buffer[2] + (m_received_frame_buffer[3] << 8);
        // Check len:
        if (4U + lengthField + 2U != nBytes)
        {
                printf(
                        "[CSickLaserSerial::LMS_waitIncomingFrame] Error: expected %u "
                        "bytes, received %u\n",
                        4U + lengthField + 2U, nBytes);
                return false;
        }
 
        // Check CRC
        uint16_t CRC = mrpt::system::compute_CRC16(
                m_received_frame_buffer, 4 + lengthField, CRC16_GEN_POL);
        uint16_t CRC_packet = m_received_frame_buffer[4 + lengthField + 0] |
                                                  (m_received_frame_buffer[4 + lengthField + 1] << 8);
        if (CRC_packet != CRC)
        {
                printf(
                        "[CSickLaserSerial::LMS_waitIncomingFrame] Error in CRC: rx: "
                        "0x%04X, computed: 0x%04X\n",
                        CRC_packet, CRC);
                return false;
        }
 
#if 0
    printf("RX: ");
    for (unsigned int i=0;i<nBytes;i++)
        printf("%02X ",m_received_frame_buffer[i]);
    printf("\n");
#endif
 
        // OK
        return true;
}
 
bool CSickLaserSerial::LMS_sendMeasuringMode_cm_mm()
{
        CSerialPort* COM = dynamic_cast<CSerialPort*>(m_stream);
        ASSERT_(COM);
 
        // **************************
        // Send command: Switch to Installation mode
        // **************************
        uint8_t cmd[128];  // =
        // {0x02,0x00,0x0A,0x00,0x20,0x00,0x53,0x49,0x43,0x4B,0x5F,0x4C,0x4D,0x53,0xBE,0xC5};
        cmd[0] = 0x20; /* mode change command */
        cmd[1] = 0x00; /* configuration mode */
        cmd[2] = 0x53;  // S - the password
        cmd[3] = 0x49;  // I
        cmd[4] = 0x43;  // C
        cmd[5] = 0x4B;  // K
        cmd[6] = 0x5F;  // _
        cmd[7] = 0x4C;  // L
        cmd[8] = 0x4D;  // M
        cmd[9] = 0x53;  // S
 
        uint16_t cmd_len = 10;
        if (!SendCommandToSICK(cmd, cmd_len))
                RET_ERROR("Error waiting ACK to installation mode");
        if (!LMS_waitIncomingFrame(500))
                RET_ERROR("Error in response to installation mode");
 
        // Check response
        if (!(m_received_frame_buffer[4] == 0xA0 &&
                  m_received_frame_buffer[5] == 0x00))
                RET_ERROR("Wrong response to installation mode");
 
        // **************************
        // Request LMS Configuration
        // **************************
        cmd[0] = 0x74;
        cmd_len = 1;
 
        if (!SendCommandToSICK(cmd, cmd_len))
                RET_ERROR("No ACK to 0x74 (req. config)");
        if (!LMS_waitIncomingFrame(500))
                RET_ERROR("No answer to 0x74 (req. config)");
 
        // 2. Check response
        if (m_received_frame_buffer[4] != 0xF4)
                RET_ERROR("No expected 0xF4 in response to 0x74 (req. config)");
 
        // ***********************************************************************
        // Configure 1/2: Measuremente Range, Measurement Unit, Master/Slave Role
        // ***********************************************************************
        // 4.a Modify some values...
 
        // Measuring mode: Measurement range 32m in mm mode, or 80m+reflectance info
        // in cm mode.
        // See page 98 in LMS2xx_list_datagrams.pdf.
        m_received_frame_buffer[10] = this->m_mm_mode ? 0x06 : 0x00;
        m_received_frame_buffer[11] = this->m_mm_mode ? 0x01 : 0x00;
 
        // 4.2 Build the output command
        m_received_frame_buffer[1] = 0x00;  // Address
        m_received_frame_buffer[2] = 0x23;  // Length (low byte)
        m_received_frame_buffer[3] = 0x00;  // Length (high byte)
        m_received_frame_buffer[4] = 0x77;  // Configure command
 
        memcpy(cmd, m_received_frame_buffer + 4, 0x23);
        cmd_len = 0x23;
 
        // 4.4 Send to the LMS
        if (!SendCommandToSICK(cmd, cmd_len))
                RET_ERROR("No ACK for config command (0x77)");
        if (!LMS_waitIncomingFrame(600))
                RET_ERROR("No answer for config command (0x77)");
 
        if (!(m_received_frame_buffer[4] == 0xF7 &&
                  m_received_frame_buffer[5] == 0x01))
                RET_ERROR("Wrong answer for config command (0x77)");
 
        // **************************
        // Switch to Monitoring mode
        // **************************
        cmd[0] = 0x20;
        cmd[1] = 0x25;
        cmd_len = 2;
        if (!SendCommandToSICK(cmd, cmd_len))
                RET_ERROR("No ACK for set monitoring mode");
        if (!LMS_waitIncomingFrame(500))
                RET_ERROR("No answer for set monitoring mode");
 
        if (!(m_received_frame_buffer[4] == 0xA0 &&
                  m_received_frame_buffer[5] == 0x00))
                RET_ERROR("Wrong answer for set monitoring mode");
 
        // All ok.
        return true;
}
 
/*-----------------------------------------------------------------
  Start continuous mode measurements.
   Returns true if response is read ok.
  -----------------------------------------------------------------*/
bool CSickLaserSerial::LMS_startContinuousMode()
{
        ASSERT_(m_scans_FOV == 100 || m_scans_FOV == 180);
        ASSERT_(m_scans_res == 25 || m_scans_res == 50 || m_scans_res == 100);
 
        CSerialPort* COM = dynamic_cast<CSerialPort*>(m_stream);
        ASSERT_(COM);
 
        uint8_t cmd[40];
 
        // Config angle/resolution
        cmd[0] = 0x3B;
        cmd[1] = m_scans_FOV;
        cmd[2] = 0x00;
        cmd[3] = m_scans_res;  // 25,50 or 100 -  1/100th of deg
        cmd[4] = 0x00;
        uint16_t cmd_len = 5;
        if (!SendCommandToSICK(cmd, cmd_len))
                RET_ERROR("Error waiting ack for change angle/resolution");
        if (!LMS_waitIncomingFrame(500))
                RET_ERROR("Error waiting answer for change angle/resolution");
 
        // Start continuous mode:
        cmd[0] = 0x20;
        cmd[1] = 0x24;
        cmd_len = 2;
        if (!SendCommandToSICK(cmd, cmd_len))
                RET_ERROR("Error waiting ack for start scanning");
        if (!LMS_waitIncomingFrame(500))
                RET_ERROR("Error waiting answer for start scanning");
 
        return true;
}
 
bool CSickLaserSerial::LMS_endContinuousMode()
{
        CSerialPort* COM = dynamic_cast<CSerialPort*>(m_stream);
        ASSERT_(COM);
 
        uint8_t cmd[40];
 
        // End continuous mode:
        cmd[0] = 0x20;
        cmd[1] = 0x25;
        uint16_t cmd_len = 2;
        if (!SendCommandToSICK(cmd, cmd_len)) return false;
        return LMS_waitIncomingFrame(50);
}
 
bool CSickLaserSerial::SendCommandToSICK(
        const uint8_t* cmd, const uint16_t cmd_len)
{
        uint8_t cmd_full[1024];
        ASSERT_(sizeof(cmd_full) > cmd_len + 4U + 2U);
 
        CSerialPort* COM = dynamic_cast<CSerialPort*>(m_stream);
        ASSERT_(COM);
 
        // Create header
        cmd_full[0] = 0x02;  // STX
        cmd_full[1] = 0;  // ADDR
        cmd_full[2] = cmd_len & 0xFF;
        cmd_full[3] = cmd_len >> 8;
 
        memcpy(cmd_full + 4, cmd, cmd_len);
 
        const uint16_t crc =
                mrpt::system::compute_CRC16(cmd_full, 4 + cmd_len, CRC16_GEN_POL);
        cmd_full[4 + cmd_len + 0] = crc & 0xFF;
        cmd_full[4 + cmd_len + 1] = crc >> 8;
 
        const size_t toWrite = 4 + cmd_len + 2;
 
        if (m_verbose)
        {
                printf("[CSickLaserSerial::SendCommandToSICK] TX: ");
                for (unsigned int i = 0; i < toWrite; i++) printf("%02X ", cmd_full[i]);
                printf("\n");
        }
 
        const int NTRIES = 3;
 
        for (int k = 0; k < NTRIES; k++)
        {
                if (toWrite != COM->Write(cmd_full, toWrite))
                {
                        cout << "[CSickLaserSerial::SendCommandToSICK] Error writing data "
                                        "to serial port."
                                 << endl;
                        return false;
                }
                std::this_thread::sleep_for(15ms);
                if (LMS_waitACK(50)) return true;
                std::this_thread::sleep_for(10ms);
        }
 
        return false;
}