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C Ping Protocol 1.0

Sample code

/*
* ping.c
*
*  Created on: 2016. 5. 16.
*      Author: Leon Ryu Woon Jung
*/

//
// *********     ping Example      *********
//
//
// Available Dynamixel model on this example : All models using Protocol 1.0
// This example is designed for using a Dynamixel MX-28, and an USB2DYNAMIXEL.
// To use another Dynamixel model, such as X series, see their details in E-Manual(support.robotis.com) and edit below "#define"d variables yourself.
// Be sure that Dynamixel MX properties are already set as %% ID : 1 / Baudnum : 1 (Baudrate : 1000000 [1M])
//

#ifdef __linux__
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
#elif defined(_WIN32) || defined(_WIN64)
#include <conio.h>
#endif

#include <stdio.h>
#include "dynamixel_sdk.h"                                   // Uses Dynamixel SDK library

// Protocol version
#define PROTOCOL_VERSION                1.0                 // See which protocol version is used in the Dynamixel

// Default setting
#define DXL_ID                          1                   // Dynamixel ID: 1
#define BAUDRATE                        1000000
#define DEVICENAME                      "/dev/ttyUSB0"      // Check which port is being used on your controller
                                                            // ex) Windows: "COM1"   Linux: "/dev/ttyUSB0"

int getch()
{
#ifdef __linux__
  struct termios oldt, newt;
  int ch;
  tcgetattr(STDIN_FILENO, &oldt);
  newt = oldt;
  newt.c_lflag &= ~(ICANON | ECHO);
  tcsetattr(STDIN_FILENO, TCSANOW, &newt);
  ch = getchar();
  tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
  return ch;
#elif defined(_WIN32) || defined(_WIN64)
  return _getch();
#endif
}

int kbhit(void)
{
#ifdef __linux__
  struct termios oldt, newt;
  int ch;
  int oldf;

  tcgetattr(STDIN_FILENO, &oldt);
  newt = oldt;
  newt.c_lflag &= ~(ICANON | ECHO);
  tcsetattr(STDIN_FILENO, TCSANOW, &newt);
  oldf = fcntl(STDIN_FILENO, F_GETFL, 0);
  fcntl(STDIN_FILENO, F_SETFL, oldf | O_NONBLOCK);

  ch = getchar();

  tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
  fcntl(STDIN_FILENO, F_SETFL, oldf);

  if (ch != EOF)
  {
    ungetc(ch, stdin);
    return 1;
  }

  return 0;
#elif defined(_WIN32) || defined(_WIN64)
  return _kbhit();
#endif
}

int main()
{
  // Initialize PortHandler Structs
  // Set the port path
  // Get methods and members of PortHandlerLinux or PortHandlerWindows
  int port_num = portHandler(DEVICENAME);

  // Initialize PacketHandler Structs
  packetHandler();

  int dxl_comm_result = COMM_TX_FAIL;             // Communication result

  uint8_t dxl_error = 0;                          // Dynamixel error
  uint16_t dxl_model_number;                      // Dynamixel model number

  // Open port
  if (openPort(port_num))
  {
    printf("Succeeded to open the port!\n");
  }
  else
  {
    printf("Failed to open the port!\n");
    printf("Press any key to terminate...\n");
    getch();
    return 0;
  }

  // Set port baudrate
  if (setBaudRate(port_num, BAUDRATE))
  {
    printf("Succeeded to change the baudrate!\n");
  }
  else
  {
    printf("Failed to change the baudrate!\n");
    printf("Press any key to terminate...\n");
    getch();
    return 0;
  }

  // Try to ping the Dynamixel
  // Get Dynamixel model number
  dxl_model_number = pingGetModelNum(port_num, PROTOCOL_VERSION, DXL_ID);
  if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
  {
    printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);
  }
  else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
  {
    printRxPacketError(PROTOCOL_VERSION, dxl_error);
  }

  printf("[ID:%03d] ping Succeeded. Dynamixel model number : %d\n", DXL_ID, dxl_model_number);

  // Close port
  closePort(port_num);

  return 0;
}

Details

#ifdef __linux__
#include <unistd.h>
#include <fcntl.h>
#include <termios.h>
#elif defined(_WIN32) || defined(_WIN64)
#include <conio.h>
#endif

This source includes above to get key input interruption while the example is running. Actual functions for getting the input is described in a little below.

#include <stdio.h>

The example shows Dynamixel status in sequence by the function printf(). So here stdio.h is needed.

#include "dynamixel_sdk.h"                                   // Uses Dynamixel SDK library

All libraries of Dynamixel SDK are linked with the header file dynamixel_sdk.h.

// Protocol version
#define PROTOCOL_VERSION                1.0                 // See which protocol version is used in the Dynamixel

Dynamixel uses either or both protocols: Protocol 1.0 and Protocol 2.0. Choose one of the Protocol which is appropriate in the Dynamixel.

// Default setting
#define DXL_ID                          1                   // Dynamixel ID: 1
#define BAUDRATE                        1000000
#define DEVICENAME                      "/dev/ttyUSB0"      // Check which port is being used on your controller
                                                            // ex) Windows: "COM1"   Linux: "/dev/ttyUSB0"

Here we set some variables to let you freely change them and use them to run the example code.

As the document previously said in previous chapter, customize Dynamixel control table items, such as DXL_ID number, communication BAUDRATE, and the DEVICENAME, on your own terms of needs. In particular, BAUDRATE and DEVICENAME have systematical dependencies on your controller, so make clear what kind of communication method you will use.

int getch()
{
#ifdef __linux__
  struct termios oldt, newt;
  int ch;
  tcgetattr(STDIN_FILENO, &oldt);
  newt = oldt;
  newt.c_lflag &= ~(ICANON | ECHO);
  tcsetattr(STDIN_FILENO, TCSANOW, &newt);
  ch = getchar();
  tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
  return ch;
#elif defined(_WIN32) || defined(_WIN64)
  return _getch();
#endif
}

int kbhit(void)
{
#ifdef __linux__
  struct termios oldt, newt;
  int ch;
  int oldf;

  tcgetattr(STDIN_FILENO, &oldt);
  newt = oldt;
  newt.c_lflag &= ~(ICANON | ECHO);
  tcsetattr(STDIN_FILENO, TCSANOW, &newt);
  oldf = fcntl(STDIN_FILENO, F_GETFL, 0);
  fcntl(STDIN_FILENO, F_SETFL, oldf | O_NONBLOCK);

  ch = getchar();

  tcsetattr(STDIN_FILENO, TCSANOW, &oldt);
  fcntl(STDIN_FILENO, F_SETFL, oldf);

  if (ch != EOF)
  {
    ungetc(ch, stdin);
    return 1;
  }

  return 0;
#elif defined(_WIN32) || defined(_WIN64)
  return _kbhit();
#endif
}

These functions accept the key inputs in terms of example action. The example codes mainly apply the function getch() rather than the function kbhit() to get information which key has been pressed.

int main()
{
  // Initialize PortHandler Structs
  // Set the port path
  // Get methods and members of PortHandlerLinux or PortHandlerWindows
  int port_num = portHandler(DEVICENAME);

  // Initialize PacketHandler Structs
  packetHandler();

  int dxl_comm_result = COMM_TX_FAIL;             // Communication result

  uint8_t dxl_error = 0;                          // Dynamixel error
  uint16_t dxl_model_number;                      // Dynamixel model number

  // Open port
  if (openPort(port_num))
  {
    printf("Succeeded to open the port!\n");
  }
  else
  {
    printf("Failed to open the port!\n");
    printf("Press any key to terminate...\n");
    getch();
    return 0;
  }

  // Set port baudrate
  if (setBaudRate(port_num, BAUDRATE))
  {
    printf("Succeeded to change the baudrate!\n");
  }
  else
  {
    printf("Failed to change the baudrate!\n");
    printf("Press any key to terminate...\n");
    getch();
    return 0;
  }

  // Try to ping the Dynamixel
  // Get Dynamixel model number
  dxl_model_number = pingGetModelNum(port_num, PROTOCOL_VERSION, DXL_ID);
  if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
  {
    printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);
  }
  else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
  {
    printRxPacketError(PROTOCOL_VERSION, dxl_error);
  }

  printf("[ID:%03d] ping Succeeded. Dynamixel model number : %d\n", DXL_ID, dxl_model_number);

  // Close port
  closePort(port_num);

  return 0;
}

In main() function, the codes call actual functions for Dynamixel control.

  // Initialize PortHandler Structs
  // Set the port path
  // Get methods and members of PortHandlerLinux or PortHandlerWindows
  int port_num = portHandler(DEVICENAME);

portHandler() function sets port path as DEVICENAME and get port_num, and prepares an appropriate functions for port control in controller OS automatically. port_num would be used in many functions in the body of the code to specify the port for use.

  // Initialize PacketHandler Structs
  packetHandler();

packetHandler() function initializes parameters used for packet construction and packet storing.

  int dxl_comm_result = COMM_TX_FAIL;             // Communication result

  uint8_t dxl_error = 0;                          // Dynamixel error
  uint16_t dxl_model_number;                      // Dynamixel model number

dxl_comm_result indicates which error has been occurred during packet communication.

dxl_error shows the internal error in Dynamixel.

dxl_model_number keeps Dynamixel model number.

  // Open port
  if (openPort(port_num))
  {
      printf("Succeeded to open the port!\n");
  }
  else
  {
      printf("Failed to open the port!\n");
      printf("Press any key to terminate...\n");
      _getch();
      return 0;
  }

First, controller opens #port_num port to do serial communication with the Dynamixel. If it fails to open the port, the example will be terminated.

  // Set port baudrate
  if (setBaudRate(port_num, BAUDRATE))
  {
      printf("Succeeded to change the baudrate!\n");
  }
  else
  {
      printf("Failed to change the baudrate!\n");
      printf("Press any key to terminate...\n");
      _getch();
      return 0;
  }

Secondly, the controller sets the communication BAUDRATE at #port_num port opened previously.

  dxl_model_number = pingGetModelNum(port_num, PROTOCOL_VERSION, DXL_ID);
  if ((dxl_comm_result = getLastTxRxResult(port_num, PROTOCOL_VERSION)) != COMM_SUCCESS)
  {
    printTxRxResult(PROTOCOL_VERSION, dxl_comm_result);
  }
  else if ((dxl_error = getLastRxPacketError(port_num, PROTOCOL_VERSION)) != 0)
  {
    printRxPacketError(PROTOCOL_VERSION, dxl_error);
  }

pingGetModelNum() function orders to the #DXL_ID Dynamixel through #port_num port. Then, it receives the dxl_model_number. The function checks Tx/Rx result and receives Hardware error. getLastTxRxResult() function and getLastRxPacketError() function get either, and then printTxRxResult() function and printRxPacketError() function show results on the console window if any communication error or Hardware error has been occurred.

  // Close port
  closePort(port_num);

  return 0;

Finally, port becomes disposed.