Boost Asio Serial Port Flush

18.08.2019

Note that boost::asio::buffercopy is implemented in terms of memcpy, and consequently it cannot be used to copy between overlapping memory regions. Buffer Invalidation. A buffer object does not have any ownership of the memory it refers to. It is the responsibility of the application to ensure the memory region remains valid until it is no longer required for an I/O operation. Construct a basicserialport without opening it. Construct and open a basicserialport. Construct a basicserialport on an existing native serial port. Move-construct a basicserialport from another. Cancel all asynchronous operations associated with the serial port. Close the serial port.

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Active2 years, 1 month ago

I've made a small interface using the asio C++ library to open serial ports and do I/O from/to them. It works with my Arduino Uno and other hardware as well (industrial weighing machines), but I only specify the port and baud rate.

The following code is run in the client application, which runs both on my Windows 10 Student Edition x86_64 machine, and on old 32 bit Win XP machines that communicate with the weighing machines:

Boost Asio Socket

Gta 4 xbox 360 torrent iso converter. The Arduino is programmed to do a serial echo of whatever is sent to it, for testing purposes. This is the echo code:

It works fine with my Arduino until I unplug it and plug it back in. After replugging it all the values returned are garbage, specifically some sort of '?' character inside a black box, don't know the bit value though, but it's constant. The problem gets fixed when I open an arduino IDE Serial Port monitor.If I close it, and once again use my own software to open up the serial port, all the values are fine.

From this I concluded that the Arduino IDE Serial Port monitor is doing something when it opens up the port that I'm not doing.

Any clues? Flow control? Handshake?Thanks

Turambar

TurambarTurambar

1 Answer

Can you include all the other calls you make related to setting up the serial port along with asio::serial_port_base::baud_rate(baudios)? Ideally, split that out into a separate function (that takes parameters such as baud rate) that you know is the only thing doing this setup.

As I mentioned in the comment, getting back the right number of chararacters but incorrect characters looks as if the baud rate is correct but something else is wrong. The first thing that comes to mind is the bits/parity/stop bits settings. Typically you want to be using 8 bits, no parity, often referred to as '8N1'.

Curt J. SampsonCurt J. Sampson

Not the answer you're looking for? Browse other questions tagged serialc++rs232boost or ask your own question.

Replace boost:asio lib with simplest one. Add enable/disable DTR function to..

Boost Asio Pdf

parentf1c286d1

Showingwith819 additionsand61 deletions

..	..	@@ -2,10 +2,16 @@ cmake_minimum_required (VERSION 2.6)
file(GLOB_RECURSE DEVICE_SOURCE_FILES *.cpp)
set(DEVICE_SOURCE_FILES
agoMySensors.cpp
MySensors.cpp
serialib.cpp
)
set(DEVICE_EXTRA_LIBRARIES
agoclient
pthread
${Boost_SYSTEM_LIBRARY}
${Boost_SYSTEM_LIBRARY}
)
set(DEVICE 'agoMySensors')
..	..

..	..	@@ -2,7 +2,6 @@
#include <stdint.h>
#include <unistd.h>
#include <iostream>
#include <boost/asio.hpp>
#include <boost/system/system_error.hpp>
#include <boost/algorithm/string/predicate.hpp>
#include <boost/algorithm/string.hpp>
..	..	@@ -11,6 +10,7 @@
#include <time.h>
#include <cstdlib>
#include <stdexcept>
#include 'serialib.h'
#include 'MySensors.h'
#include 'agoclient.h'
..	..	@@ -23,7 +23,6 @@
usingnamespacestd;
usingnamespaceagocontrol;
usingnamespaceboost::system;
usingnamespaceboost::asio;
usingnamespaceqpid::types;
namespacefs=::boost::filesystem;
..	..	@@ -54,8 +53,7 @@ qpid::types::Variant::Map devicemap;
std::map<std::string,T_COMMAND>commandsmap;
std::stringgateway_protocol_version='1.4';
io_serviceioService;
serial_portserialPort(ioService);
serialibserialPort;
stringdevice=';
intstaleThreshold=86400;
..	..	@@ -89,25 +87,6 @@ std::string timestampToStr(const time_t* timestamp)
returnstd::string(hr);
}
/**
* @brief Flush a serial port's buffers.
* @param serial_port Port to flush.
* @param what Determines the buffers to flush.
* @param error Set to indicate what error occurred, if any.
* @info http://stackoverflow.com/questions/22581315/how-to-discard-data-as-it-is-sent-with-boostasio
*/
voidflush_serial_port(boost::asio::serial_port&serial_port,flush_typewhat,boost::system::error_code&error)
{
if(0::tcflush(serial_port.lowest_layer().native_handle(),what))
{
error=boost::system::error_code();
}
else
{
error=boost::system::error_code(errno,boost::asio::error::get_system_category());
}
}
/**
* Make readable device infos
*/
..	..	@@ -352,17 +331,21 @@ bool openSerialPort(string device)
boolresult=true;
try
{
serialPort.open(device);
serialPort.set_option(serial_port::baud_rate(115200));
serialPort.set_option(serial_port::parity(serial_port::parity::none));
serialPort.set_option(serial_port::character_size(serial_port::character_size(8)));
serialPort.set_option(serial_port::stop_bits(serial_port::stop_bits::one));
serialPort.set_option(serial_port::flow_control(serial_port::flow_control::none));
//flush serial content
//boost::system::error_code error;
//flush_serial_port(serialPort, flush_both, error);
//if( DEBUG )
// cout << 'Flushing serial port: ' << error.message() << endl;
intres=serialPort.Open(device.c_str(),115200);
if(res!=1)
{
cerr<<'Can't open serial port: '<<res<<endl;
result=false;
}
else
{
//reset arduino
serialPort.EnableDTR(false);
//TODO flush
sleep(1);
serialPort.EnableDTR(true);
}
}
catch(std::exceptionconst&ex)
{
..	..	@@ -377,7 +360,7 @@ bool openSerialPort(string device)
*/
voidcloseSerialPort(){
try{
serialPort.close();
serialPort.Close();
}
catch(std::exceptionconst&ex){
//cerr << 'Can't close serial port: ' << ex.what() << endl;
..	..	@@ -434,7 +417,7 @@ void sendcommand(std::string command)
time_tt=time(NULL);
cout<<' => '<<timestampToStr(&t)<<' RE-SENDING: '<<command;
}
serialPort.write_some(buffer(command));
serialPort.WriteString(command.c_str());
}
voidsendcommandV14(std::stringinternalid,intmessageType,intack,intsubType,std::stringpayload)
{
..	..	@@ -468,7 +451,7 @@ void sendcommandV14(std::string internalid, int messageType, int ack, int subTyp
time_tt=time(NULL);
cout<<' => '<<timestampToStr(&t)<<' SENDING: '<<command.str();
}
serialPort.write_some(buffer(command.str()));
serialPort.WriteString(command.str().c_str());
}
voidsendcommandV13(std::stringinternalid,intmessageType,intsubType,std::stringpayload)
{
..	..	@@ -502,7 +485,7 @@ void sendcommandV13(std::string internalid, int messageType, int subType, std::s
time_tt=time(NULL);
cout<<' => '<<timestampToStr(&t)<<' SENDING: '<<command.str();
}
serialPort.write_some(buffer(command.str()));
serialPort.WriteString(command.str().c_str());
}
/**
..	..	@@ -516,7 +499,8 @@ qpid::types::Variant::Map commandHandler(qpid::types::Variant::Map command) {
std::stringinternalid=';
if(DEBUG)
cout<<'CommandHandler'<<command<<endl;
if(command.count('internalid')1&&command.count('command')1){
if(command.count('internalid')1&&command.count('command')1)
{
//get values
cmd=command['command'].asString();
internalid=command['internalid'].asString();
..	..	@@ -536,15 +520,18 @@ qpid::types::Variant::Map commandHandler(qpid::types::Variant::Map command) {
std::stringstreamdeviceNameType;
deviceNameType<<it->first.c_str()<<' (';
infos=getDeviceInfos(it->first);
if(infos.size()>0&&!infos['type'].isVoid()){
if(infos.size()>0&&!infos['type'].isVoid())
{
deviceNameType<<infos['type'];
}
else{
else
{
deviceNameType<<'unknown';
}
deviceNameType<<')';
content['device']=deviceNameType.str().c_str();
if(!content['last_timestamp'].isVoid()){
if(!content['last_timestamp'].isVoid())
{
int32_ttimestamp=content['last_timestamp'].asInt32();
content['datetime']=timestampToStr((time_t*)&timestamp);
}
..	..	@@ -559,9 +546,11 @@ qpid::types::Variant::Map commandHandler(qpid::types::Variant::Map command) {
{
//reset all counters
qpid::types::Variant::Mapdevices=devicemap['devices'].asMap();
for(qpid::types::Variant::Map::iteratorit=devices.begin();it!=devices.end();it++){
for(qpid::types::Variant::Map::iteratorit=devices.begin();it!=devices.end();it++)
{
infos=getDeviceInfos(it->first);
if(infos.size()>0){
if(infos.size()>0)
{
infos['counter_received']=0;
infos['counter_sent']=0;
infos['counter_retries']=0;
..	..	@@ -754,7 +743,7 @@ std::string readLine(bool* error) {
(*error)=false;
try{
for(;;){
boost::asio::read(serialPort,boost::asio::buffer(&c,1));
serialPort.ReadChar(&c,0);
switch(c){
case'r':
break;
..	..	@@ -1729,14 +1718,6 @@ int main(int argc, char **argv)
// determine reply for INTERNAL;I_UNIT message - defaults to 'M'etric
if(getConfigSectionOption('system','units','SI')!='SI')units='I';
//open serial port
if(DEBUG)
cout<<'Opening serial port '<<device<<'..'<<endl;
if(!openSerialPort(device))
{
exit(1);
}
// load map, create sections if empty
fs::pathdmf=getConfigPath(DEVICEMAPFILE);
devicemap=jsonFileToVariantMap(dmf);
..	..	@@ -1752,18 +1733,34 @@ int main(int argc, char **argv)
variantMapToJSONFile(devicemap,dmf);
}
boolerror;
cout<<'Requesting gateway version..'<<flush;
std::stringgetVersion='0;0;3;0;2n';
//open serial port
if(DEBUG)
cout<<'Opening serial port '<<device<<'..'<<endl;
if(!openSerialPort(device))
{
exit(1);
}
//connect to gateway
boolerror=false;
std::stringline=';
cout<<'Waiting for gateway started..'<<endl<<flush;
while(!error&&line.find('Gateway startup complete')string::npos)
{
line=readLine(&error);
if(DEBUG)
cout<<'Read: '<<line<<endl<<flush;
}
cout<<'Done.'<<endl<<flush;
cout<<'Requesting gateway version..'<<endl<<flush;
std::stringgetVersion='0;0;3;0;2n';
serialPort.WriteString(getVersion.c_str());
while(!error&&!boost::algorithm::starts_with(line,'0;0;3;0;2;'))
{
line=readLine(&error);
if(DEBUG)
{
cout<<'Read: '<<line<<endl;
}
serialPort.write_some(buffer(getVersion));
cout<<'Read: '<<line<<endl<<flush;
}
if(!error)
{
..	..

/*!

file serialib.h

brief Serial library to communicate throught serial port, or any device emulating a serial port.

author Philippe Lucidarme (University of Angers) <serialib@googlegroups.com>

version 1.2

date 28 avril 2011

This Serial library is used to communicate through serial port.

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,

INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR

PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE X CONSORTIUM BE LIABLE FOR ANY CLAIM,

DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

This is a licence-free software, it can be used by anyone who try to build a better world.

#ifndef SERIALIB_H

#define SERIALIB_H

// Used for TimeOut operations

#include <sys/time.h>

// Include for windows

#if defined (_WIN32) defined( _WIN64)

// Accessing to the serial port under Windows

#include <windows.h>

#endif

// Include for Linux

#ifdef __linux__

#include <stdlib.h>

#include <sys/types.h>

#include <sys/shm.h>

#include <termios.h>

#include <string.h>

#include <iostream>

// File control definitions

#include <fcntl.h>

#include <unistd.h>

#include <sys/ioctl.h>

#endif

/*! class serialib

brief This class can manage a serial port. The class allows basic operations (opening the connection, reading, writing data and closing the connection).

example Example1.cpp

classserialib

{

public:

// Constructor of the class

serialib();

// Destructor

~serialib();

//_________________________________________

// ::: Configuration and initialization :::

// Open a device

charOpen(constchar*Device,constunsignedintBauds);

// Close the current device

voidClose();

//___________________________________________

// ::: Read/Write operation on characters :::

// Write a char

charWriteChar(char);

// Read a char (with timeout)

charReadChar(char*pByte,constunsignedintTimeOut_ms=0);

//________________________________________

// ::: Read/Write operation on strings :::

// Write a string

charWriteString(constchar*String);

// Read a string (with timeout)

intReadString(char*String,

charFinalChar,

unsignedintMaxNbBytes,

constunsignedintTimeOut_ms=0);

// _____________________________________

// ::: Read/Write operation on bytes :::

// Write an array of bytes

charWrite(constvoid*Buffer,constunsignedintNbBytes);

// Read an array of byte (with timeout)

intRead(void*Buffer,unsignedintMaxNbBytes,constunsignedintTimeOut_ms=0);

// _________________________

// ::: Special operation :::

//enable/disable DTR

intEnableDTR(boolenable);

// Empty the received buffer

voidFlushReceiver();

// Return the number of bytes in the received buffer

intPeek();

private:

// Read a string (no timeout)

intReadStringNoTimeOut(char*String,charFinalChar,unsignedintMaxNbBytes);

#if defined (_WIN32) defined( _WIN64)

HANDLEhSerial;

COMMTIMEOUTStimeouts;

#endif

#ifdef __linux__

intfd;

#endif

};

/*! class TimeOut

brief This class can manage a timer which is used as a timeout.

// Class TimeOut

classTimeOut

{

public:

// Constructor

TimeOut();

// Init the timer

voidInitTimer();

// Return the elapsed time since initialization

unsignedlongintElapsedTime_ms();

private:

structtimevalPreviousTime;

};

/*!

mainpage serialib class

brief

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The class serialib offers simple access to the serial port devices for windows and linux. It can be used for any serial device (Built-in serial port, USB to RS232 converter, arduino board or any hardware using or emulating a serial port)

image html serialib.png

The class can be used under Windows and Linux.

The class allows basic operations like :

- opening and closing connection

- reading data (characters, array of bytes or strings)

- writing data (characters, array of bytes or strings)

- non-blocking functions (based on timeout).

author Philippe Lucidarme (University of Angers) <serialib@googlegroups.com>

date 1th may 2011 (Last update: 25th september 2012)

version 1.2

THE SOFTWARE IS PROVIDED 'AS IS', WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED,

INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR

PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE X CONSORTIUM BE LIABLE FOR ANY CLAIM,

DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING

FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

This is a licence-free software, it can be used by anyone who try to build a better world.

#endif // SERIALIB_H

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