Tag: linux

(I) Programming serial port communications

This entry is part 1 of 2 in the series Serial communications

250px-Serial_portConnections and operating system symbolic names

A serial port is a communication physical interface through which information  transfers in or out one bit at a time (in contrast to a parallel port) being, more or less compliant, with the RS-232 standard.

But serial port communications aren’t only useful for wired DE-9 connectors. it also allows us to use it with USB (ftdi), Bluetooth (serial profile) and Zigbee using virtual serial ports.

·

Types-usbSerial and virtual serial ports appear as  COMx in Windows operating systems (COM1, COM2, …) andin UNIX/Linux as ttySx or ttyUSBx or even ttyACMx (ttyS0, ttyS1, ttyUSB0, ttyUSB1, ttyACM0, ttyACM1,…).

For programming purposes we usually want to communicate computers with others computers, microcontrollers or other devices like GPS, LED or LCD displays.

·

Serial port programming in C/C++, Windows and Linux

Using the serial port is a lot  easier, but sometimes tricky. The basic commands are to open a connection, read and write over this connection and, finally, tom close it, better if using the C++ RAII idiom.

winWindows commands:
Here you can find a complete C++ for Windows example.

With these next two definitions (among others needed):

HANDLE
serialPortHandle
wchar_t* device

serialPortHandle = CreateFile(device, GENERIC_READ | GENERIC_WRITE, 0, NULL, OPEN_EXISTING, NULL, NULL);
if (serialPortHandle!=INVALID_HANDLE_VALUE)
ReadFile(serialPortHandle, buffer, len, &read_nbr, NULL);

if (serialPortHandle!=INVALID_HANDLE_VALUE)
WriteFile(serialPortHandle, buffer, len, &result, NULL);
CloseHandle(serialPortHandle);

linuxUnix/Linux commands:
Here you can find a complete C++ for Linux example.

With these two definitions:

·
int fileDescriptor;
char *device;
·
·
  • Opening a connection, open
struct termios terminalAttributes;

fileDescriptor = open(device, O_RDWR | O_NOCTTY | O_NDELAY | O_FSYNC );

// clear terminalAttributes data
memset(&terminalAttributes, 0, sizeof(struct termios));

terminalAttributes.c_cflag = B57600 | CS8 | CLOCAL | CREAD; 
terminalAttributes.c_iflag = IGNPAR |  ONLCR;
terminalAttributes.c_oflag = OPOST;
terminalAttributes.c_cc[VTIME] = 0;
terminalAttributes.c_cc[VMIN] = 1;

tcsetattr(fileDescriptor, TCSANOW, &terminalAttributes);
int n=read(fileDescriptor, buffer, len);

int n=write(fileDescriptor, buffer, len);
  • Closing the connection, close
close(fileDescriptor);

More information:

https://en.wikipedia.org/wiki/Serial_communication
http://en.wikipedia.org/wiki/Serial_port

http://www.lvr.com/serport.htm
http://digilander.libero.it/robang/rubrica/serial.htm
http://en.wikibooks.org/wiki/Serial_Programming

http://msdn.microsoft.com/en-us/library/ff802693.aspx

[UPDATED] A simple but pretty complete Linux C++ example for Bioloid

This entry is part 5 of 6 in the series Bioloid Workshop

[Jun 12, 2013, Some source code typos fixed and code updated]:

.
.
.
.
.

bool nonValidOption(int option)
{
  return (optionMaxOption);
}

This is a very simple but pretty complete example, trying to use the least possible dependencies. I have tested in a just installed Ubuntu and you only needed the AXControl library (I created and use it because then there were no Robotis library and because it can use serial port, Dynamixel bus, Zigbee, BT (Robotis or other adaptors)

It use the terminal, no QT, to avoid library dependencies. But you should add the AXControl_v2 lib files to your /usr/lib folder as administrator (sudo). Click here if you want one unique executable for Linux (tested with Linux Mint 14) using these sources files

When executed, it shows the values configured in the HexaWheels.conf file and any problem it founds, like SerialPort2Dynamixel.open(ss)=> [Serial port NOT opened]:


ubuntu@A3820 ~/projects/trunk/bioloid/Herramientas/CommandLine $ ./commandline
init to load configuration(ss)=> [./HexaWheels.conf]
Configuration file=> (ss)=> [./HexaWheels.conf]
Tiempo_Espera_ms(ss)=> [35]
Tiempo_Espera_Sensores_ms(ss)=> [60]
Nombre_Puerto_Serie(ss)=> [/dev/ttyUSB0]
Baudios_Puerto_Serie(ss)=> [1000000]
Motion_File_Name(ss)=> [HexaWheels_2.0.mtn]
UmbralContacto(ss)=> [550]
UmbralDeteccion(ss)=> [200]
loadConfigurationValues: (si)=> [134529476]
getIntValue: (ss)=> [Tiempo_Espera_ms]
getIntValue: (ss)=> [Tiempo_Espera_Sensores_ms]
getIntValue: (ss)=> [Baudios_Puerto_Serie]
getStringValue: (ss)=> [Nombre_Puerto_Serie]

Device /dev/ttyUSB0, Speed B1000000
SerialPort2Dynamixel.open(ss)=> [Serial port NOT opened]
SerialPort2Dynamixel.open, serialPortName(ss)=> [/dev/ttyUSB0]
SerialPort2Dynamixel.open, baudRate(si)=> [4104]
I can’t open DynamixelCommunication, name: (ss)=> [/dev/ttyUSB0]
terminate called after throwing an instance of ‘std::exception*’
Aborted

If it can connect an there are no problem you should see:


ubuntu@A3820 ~/projects/trunk/bioloid/Herramientas/CommandLine $ ./commandline
init to load configuration(ss)=> [./HexaWheels.conf]
Configuration file=> (ss)=> [./HexaWheels.conf]
Tiempo_Espera_ms(ss)=> [35]
Tiempo_Espera_Sensores_ms(ss)=> [60]
Nombre_Puerto_Serie(ss)=> [/dev/ttyUSB0]
Baudios_Puerto_Serie(ss)=> [1000000]
Motion_File_Name(ss)=> [HexaWheels_2.0.mtn]
UmbralContacto(ss)=> [550]
UmbralDeteccion(ss)=> [200]
loadConfigurationValues: (si)=> [134529476]
getIntValue: (ss)=> [Tiempo_Espera_ms]
getIntValue: (ss)=> [Tiempo_Espera_Sensores_ms]
getIntValue: (ss)=> [Baudios_Puerto_Serie]
getStringValue: (ss)=> [Nombre_Puerto_Serie]

Device /dev/ttyUSB0, Speed B1000000
SerialPort2Dynamixel.open, serialPortName(ss)=> [/dev/ttyUSB0]
SerialPort2Dynamixel.open, baudRate(si)=> [4104]
V01
2.- Toggle AX-12 LED
3.- Query AX-12
4.- Move AX-12
5.- Torque AX-12
6.- Query CM-510 sensor
7.- Show menu
8.- Beep
9.- Quit
Select option (2-9)


/*------------------------------------------------------------------------------*\
 * This source file is subject to the GPLv3 license that is bundled with this   *
 * package in the file COPYING.                                                 *
 * It is also available through the world-wide-web at this URL:                 *
 * http://www.gnu.org/licenses/gpl-3.0.txt                                      *
 * If you did not receive a copy of the license and are unable to obtain it     *
 * through the world-wide-web, please send an email to                          *
 * siempre.aprendiendo@gmail.com so we can send you a copy immediately.         *
 *                                                                              *
 * @category  Robotics                                                          *
 * @copyright Copyright (c) 2011 Jose Cortes (<a href="https://plus.google.com/105007891378677151287/about">https://plus.google.com/105007891378677151287/about</a>) *
 * @license   http://www.gnu.org/licenses/gpl-3.0.txt GNU v3 Licence            *
 *                                                                              *
\*------------------------------------------------------------------------------*/

#include "stdafx.h"
#include
#include "BasicSystem.h"
#include "Util.h"

using namespace std;

class UI
{
public:
  static const int OptionQuit=8;

  UI(MyBasicSystem::BasicSystem& aMySystem) : mySystem(aMySystem) {}

  void showMenu();
  int selectOption();
  bool executeSelectedOption(int selected);
  void doBeep();

private:
  MyBasicSystem::BasicSystem mySystem;

  static const int OptionSetLEDOnOff=1;
  static const int OptionQueryAX12=2;
  static const int OptionMoveAX12=3;
  static const int OptionTorqueAX12=4;
  static const int OptionQuerySensor=5;
  static const int OptionShowMenu=6;
  static const int OptionBeep=7;

  static const int MinOption=OptionSetLEDOnOff;
  static const int MaxOption=OptionQuit;

  bool validRange(int value, int MinValue, int MaxValue);
  bool nonValidOption(int option);
  int getPosition();
  int getId();
  int getSensorPort();
  void doGetPosition();
  void doSetPosition();
  void doQuerySensor();
  void doSetLEDOnOff();
  void doSetTorqueOnOff();

};

void UI::showMenu()
{
  cout << "V02" << endl;

  cout << OptionSetLEDOnOff << ".- Toggle AX-12 LED" << endl;
  cout << OptionQueryAX12 << ".- Query AX-12" << endl;
  cout << OptionMoveAX12 << ".- Move AX-12" << endl;
  cout << OptionTorqueAX12 << ".- Torque AX-12" << endl;
  cout << OptionQuerySensor << ".- Query CM-510 sensor" << endl;
  cout << OptionShowMenu << ".- Show menu" << endl;
  cout << OptionBeep << ".- Beep" << endl;
  cout << OptionQuit << ".- Quit" << endl;
}

bool UI::nonValidOption(int option)
{
  return (optionMaxOption);
}

int UI::selectOption()
{
  int option=-1;

  while (nonValidOption(option))
  {
    cout << "Select option (" << MinOption << "-" << MaxOption << ")" << endl;     cin >> option;
    if (nonValidOption(option))
    {
      cout << endl;
      cout << endl;
      cout << "(" << option << ") is NOT a valid option" << endl;     }   }   return option; } bool UI::validRange(int value, int MinValue, int MaxValue) {   return (value>=MinValue && value<=MaxValue);
}

int UI::getPosition()
{
  int position=0;

  do
  {
    cout << "Type a value between 0 and 1023 to set the AX-12 in that position" << endl;     cin>>position;

  }while(!validRange(position, 0, 1023));

  cout << "Position:" <<  position << endl;   return position; } int UI::getId() {   int ax12Id=1;   do   {     puts ("Type the ID of the AX-12 to use, a value between 1 and 18, ");     cin >> ax12Id;

  }while(!validRange(ax12Id, 1, 18));

  cout << "AX12 Id:" << ax12Id << endl;   return ax12Id; } int UI::getSensorPort() {   int sensorPort=1;   do   {     puts ("Type the sensor Port to read, a value between 1 and 6, ");     cin >> sensorPort;

  }while(!validRange(sensorPort, 1, 6));

  cout << "Sensor Port number:" << sensorPort << endl;

  return sensorPort;
}

void UI::doBeep()
{
  cout << "Beep" << endl;
  mySystem.dynamixelCommunication.sendOrder(100, AXS1_Buzzer, (byte) DO, (short) 500);
  Sleep (2);
  mySystem.dynamixelCommunication.sendOrder(200, MyCommunications::Beep, (byte) 5);
}

void UI::doGetPosition()
{
  int ax12Id=getId();

  int position = mySystem.dynamixelCommunication.readValue(ax12Id, MyCommunications::PresentPosition);
  cout << "the position is: [" << position << "] " << endl << endl << endl;
}

void UI::doSetPosition()
{
  int ax12Id=getId();
  int position=getPosition();

  mySystem.dynamixelCommunication.sendOrder(ax12Id, MyCommunications::GoalPosition,(short) position);

}

void UI::doQuerySensor()
{
  int sensorPort=getSensorPort();

  int value=mySystem.dynamixelCommunication.readSensorValue (200, ReadCM510SensorRaw, sensorPort);
  cout << "the sensor reads: [" << value << "] " << endl << endl << endl;
}

void UI::doSetLEDOnOff()
{
  byte lByte=0, hByte=0;
  int ledValue;

  int ax12Id=getId();

  ledValue=mySystem.dynamixelCommunication.readValue(ax12Id, MyCommunications::LED);
  Hex::toHexHLConversion(ledValue, hByte, lByte);

  bool onOff=false;
  if (lByte!=0)
    onOff=true;

  cout << "The LED is: [" << (onOff?"on":"off") << "], putting it: [" << (onOff?"Off":"on") << "] " << endl << endl << endl;
  mySystem.dynamixelCommunication.sendOrder(ax12Id, MyCommunications::LED, byte(onOff?0:1));
}

void UI::doSetTorqueOnOff()
{
  byte lByte=0, hByte=0;
  int ax12Id=getId();

  int torque=mySystem.dynamixelCommunication.readValue(ax12Id, MyCommunications::Torque);
  Hex::toHexHLConversion(torque, hByte, lByte);
  bool onOff=(lByte!=0?true:false);

  cout << "The Torque is: [" << (onOff?"on":"off") << "], putting it: [" << (onOff?"Off":"on") << "] " << endl << endl << endl;

  mySystem.dynamixelCommunication.sendOrder(ax12Id, MyCommunications::Torque,(byte) (onOff?0:1));
}

bool UI::executeSelectedOption(int option)
{
  bool isOk=true;
  cout << endl;
  cout << endl;

  cout << "Selected option: [" << option << "] " << endl;

  switch(option)
  {
    case OptionSetLEDOnOff:
         doSetLEDOnOff();
         break;
    case OptionQueryAX12:
         doGetPosition();
         break;
    case OptionMoveAX12:
         doSetPosition();
         break;
    case OptionTorqueAX12:
         doSetTorqueOnOff();
         break;
    case OptionQuerySensor:
         doQuerySensor();
         break;
    case OptionShowMenu:
	 showMenu();
	 break;
    case OptionBeep:
         doBeep();
         break;
  }

  return isOk;
}

int _tmain(int argc, _TCHAR* argv[])
{
  cout << "AXControl_v2_VS_CPP test v0" << endl;

  bool quit=false;
  MyBasicSystem::BasicSystem mySystem;
  UI ui(mySystem);
  do
  {
    ui.showMenu();
    int selected=ui.selectOption();
    if (selected==ui.OptionQuit)
	quit=true;
    ui.executeSelectedOption(selected);
  }while (!quit);

  mySystem.dynamixelCommunication.close();

	return 0;
}

So… let’s the Bioloid, C++ and QT games start!

This entry is part 4 of 6 in the series Bioloid Workshop

To cretate this workshop I’m using Ubuntu 12.04, GNU g++ (Ubuntu/Linaro 4.6.3-1ubuntu5) 4.6.3 (see Synaptic installer capture),

Synaptic G++

Synaptic G++

QT 5.0.1 and QT creator 2.6.2,

QT creator is a very easy, and good, free IDE with a great design tool for creating user interfaces:

Be careful with this bug: Qt Creator 2.0: UI layout is not updated before launching the application http://qt-project.org/forums/viewthread/292 Is very annoying and time consuming, the solution is in the last comment (setting the UI_DIR in the .pro file)

QTCreator Bioloid QTWorkshop

QTCreator Bioloid QTWorkshop

I also will use it with Windows 7.

I also use Boost to get some C++11 features for threading. For example:

pWorkThread = new thread(&Activity::doWork, this, parameter);

std::lock_guard < std::mutex > guard(myMutex);

Don’t bother if you don’t understand it right now, it’s in the guts of the AXControl_v2 library we will use it in a very easy way, as you will see below. Here you will find a lot of resources to learn basic and advanced C++

Example context fot std::lock_guard < std::mutex > guard(myMutex);


short DynamixelCommunication::readSensorValue(int id, AX12Address address,
int port) {
std::lock_guard < std::mutex > guard(myMutex);
short value = -1;
try {
int size = getReadSensorWordCommand(buffer, (byte) (id), address,
(byte) (port));
memset(&result, 0, MaxBufferSize);
serialPort.query(buffer, result, size, WaitTimeReadSensor);
value = getQueryResult(result, size);
if (value <= 0)
Debug::show("DynamixelCommunication.readSensorValue", value);

} catch (exception e) {
Debug::show("DynamixelCommunication.readSensorValue", e.what());
}
return value;
}

And context for pWorkThread = new thread(&Activity::doWork, this, parameter);:


class Activity {
private:

protected:
std::thread *pWorkThread;

...

}

void Activity::start(int parameter) {
working = true;
pWorkThread = new thread(&Activity::doWork, this, parameter);
Util::sleepMS(10);
}
Let's see how to open the connection

Let’s see how to open the connection to the CM-510:

void MainWindow::on_B_Open_clicked()
{
//QString output="Open it";
//QMessageBox::information(this, "Output", output, QMessageBox::Ok);

//dynComm.open("/dev/ttyUSB0",57600); //open with these parameters
if (pDynComm->open()) //open getting the parameter from the configuration fiel
{
//Connection opened
setConnectionButtons(true); //User interface update
updateAX12Parameters(ui->SB_AX12_1_ID->text().toInt()); //User interface update
}
else
{
//Show problem opening the connection
string cantOpenPortName="I can't open port: ";
cantOpenPortName+=pConf->getStringValue(DynamixelCommunication::ParameterSerialPortName);

QMessageBox::information(this, "Error", QString::fromStdString(cantOpenPortName), QMessageBox::Ok);
}
}

and get a beep from the Robotis CM-510 (using this alternative firmware):

pDynComm->sendOrder(200, MyCommunications::BeepCM510, 0); //200 is the Dynamixel device ID used for the CM-510, 0 because beep doesn't need any additional value

Getting the AX12 position and showing it:

void MainWindow::on_B_AX12_1_GET_POS_clicked()
{
    QString qStr;

    int id = getAX12_1_Id();

    int position = pDynComm->readValue(id, MyCommunications::PresentPosition);

    ui->SB_AX12_1_POS->setValue(position);

Setting the AX12 position:

void MainWindow::on_B_AX12_1_SET_POS_clicked()
{
    int id = getAX12_1_Id();

    int position= ui->SB_AX12_1_POS->text().toInt();
    pDynComm->sendOrder(id, MyCommunications::GoalPosition,position);
}

Putting the selected AX12 LED on and off

void MainWindow::on_CH_AX12_1_LED_clicked(bool checked)
{
    int id = getAX12_1_Id();

    pDynComm->sendOrder(id, MyCommunications::LED, (checked?1:0));// if checked 1, else 0
}

And an auxiliary UI method to get the id from the selected AX-12

{
int MainWindow::getAX12_1_Id()
{
    QString qStr=ui->SB_AX12_1_ID->text();
    int id=Util::convertToInt(qStr.toStdString());

    return id;
}

You can download sources and Linux binaries here

A diagram with all the AXControl_v2 lib classes and their methods:

c++ signatura

c++ signatura

[Update]

QT5 Bioloid Workbench

QT5 Bioloid Workbench

Linux C++ Dynamixel reading and writing example

This entry is part 4 of 5 in the series Bioloid C++ tutorial

If you will like to use some boards like Raspberry or Beagleboard C++ is a great choice. So here you have a working Linux C++ Dynamixel reading and writing example. The main difference is the serial port access:

Here you can download the Eclipse project zipped. and here a simple but pretty complete Linux C++ example for Bioloid

Here you can find several combinations of hardware, firmware and programming tools.

The main body

#include
using namespace std;

#include "SerialPort.h"
#include "Dynamixel.h"

int main() {
cout << "AX Control starts" << endl; // prints AX Control int error=0; int idAX12=18; SerialPort serialPort; Dynamixel dynamixel; if (serialPort.connect("//dev//ttyS0")!=0) { dynamixel.sendTossModeCommand(&serialPort); int pos=dynamixel.getPosition(&serialPort, idAX12); if (pos>250 && pos <1023)
dynamixel.setPosition(&serialPort, idAX12, pos-100);
else
printf ("nPosition <%i> under 250 or over 1023n", pos);

serialPort.disconnect();
}
else {
printf ("nCan't open serial port");
error=-1;
}

cout << endl << "AX Control ends" << endl; // prints AX Control
return error;
}

Header

#ifndef SERIALPORT_H_
#define SERIALPORT_H_

#include
#include
#include
#include

class SerialPort {
private:
int fileDescriptor;

public:
int connect ();
int connect (char * device);
void disconnect(void);

int sendArray(unsigned char *buffer, int len);
int getArray (unsigned char *buffer, int len);

int bytesToRead();
void clear();
};

#endif /* SERIALPORT_H_ */

Body:

#include
#include <sys/ioctl.h>

#include "SerialPort.h"

int SerialPort::connect() {
return connect("//dev//ttyS0");
}

int SerialPort::connect(char *device) {
struct termios terminalAttributes;

/*
* http://linux.die.net/man/2/open
*
* Open the serial port
* read/write
* not become the process's controlling terminal
* When possible, the file is opened in nonblocking mode
*
*/
fileDescriptor = open(device, O_RDWR | O_NOCTTY | O_NDELAY | O_FSYNC );

// clear terminalAttributes data
memset(&terminalAttributes, 0, sizeof(struct termios));

/*    http://linux.die.net/man/3/termios
*
*  control modes: c_cflag flag constants:
*
* 57600 bauds
* 8 bits per word
* Ignore modem control lines.
* Enable receiver.
*/

terminalAttributes.c_cflag = B57600 | CS8 | CLOCAL | CREAD;

/*
* input modes: c_iflag flag constants:
*
* Ignore framing errors and parity errors.
* (XSI) Map NL to CR-NL on output.
*/
terminalAttributes.c_iflag = IGNPAR |  ONLCR;

/*
* output modes: flag constants defined in POSIX.1
*
* Enable implementation-defined output processing.
*/

terminalAttributes.c_oflag = OPOST;

/*
* Canonical and noncanonical mode
*
* min time
* min bytes to read
*/

//terminalAttributes.c_lflag = ICANON;
terminalAttributes.c_cc[VTIME] = 0;
terminalAttributes.c_cc[VMIN] = 1;

/*
* http://linux.die.net/man/3/tcsetattr
* Set the port to our state
*
* the change occurs immediately
*/

tcsetattr(fileDescriptor, TCSANOW, &terminalAttributes);

/*
* http://linux.die.net/man/3/tcflush
*
* flushes data written but not transmitted.
* flushes data received but not read.
*/

tcflush(fileDescriptor, TCOFLUSH);
tcflush(fileDescriptor, TCIFLUSH);

return fileDescriptor;
}

void SerialPort::disconnect(void)
{
close(fileDescriptor);
printf("nPort 1 has been CLOSED and %d is the file descriptionn", fileDescriptor);
}

int SerialPort::sendArray(unsigned char *buffer, int len) {
int n=write(fileDescriptor, buffer, len);
return n;
}

int SerialPort::getArray (unsigned char *buffer, int len)
{
int n1=bytesToRead();
int n=read(fileDescriptor, buffer, len);
return n;
}

void SerialPort::clear()
{
tcflush(fileDescriptor, TCIFLUSH);
tcflush(fileDescriptor, TCOFLUSH);
}

int SerialPort::bytesToRead()
{
int bytes=0;
ioctl(fileDescriptor, FIONREAD, &bytes);

return bytes;
}
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