c++ - Reading Serial Data from Arduino, Corrupted Data -
i using arduino due , visual studio 2010. programming in c/c++. below see programs , after explanations of going wrong.
this simple code thats on arduino. sending lot of a's pc.
void setup() { // initialize serial communication @ 9600 bits per second: serial.begin(9600); } void loop() { serial.println('a'); delay(1); // delay in between reads stability } the further code reading serial port found on here: http://playground.arduino.cc/interfacing/cppwindows
and modified version of code @ moment:
header:
#ifndef serialclass_h_included #define serialclass_h_included #define arduino_wait_time 2000 #include <windows.h> #include <stdio.h> #include <stdlib.h> class serial { private: //serial comm handler handle hserial; //connection status bool connected; //get various information connection comstat status; //keep track of last error dword errors; public: //initialize serial communication given com port serial(char *portname); //close connection //nota: reason can't connect again before exiting //the program , running again ~serial(); //read data in buffer, if nbchar greater //maximum number of bytes available, return //bytes available. function return -1 when nothing //be read, number of bytes read. int readdata(char *buffer, unsigned int nbchar); //writes data buffer through serial connection //return true on success. bool writedata(char *buffer, unsigned int nbchar); //check if connected bool isconnected(); }; #endif // serialclass_h_included cpp:
#include "stdafx.h" #include <stdio.h> #include <tchar.h> #include "serialclass.h" #include <string> #include <windows.h> #include <assert.h> #include <stdlib.h> #include <iostream> #include <fstream> #include <conio.h> using namespace system; using namespace std; // serial::serial looks, if serial connection pc device proper , working. sets few parameters , waits serial::serial(char *portname) { //we're not yet connected this->connected = false; //try connect given port throuh createfile this->hserial = createfilea(portname, generic_read | generic_write, 0, null, open_existing, file_attribute_normal, null); //check if connection successfull //if not...show error if(this->hserial==invalid_handle_value) { //if not success full display error if(getlasterror()==error_file_not_found){ //print error if neccessary printf("error: handle not attached. reason: %s not available.\n", portname); sleep(2000); } else {printf("error!!!");} } // else = connection working, -> continue else { //if connected try set comm parameters dcb dcbserialparams = {0}; //try current parameters if (!getcommstate(this->hserial, &dcbserialparams)) { //if impossible, show error printf("failed current serial parameters!"); } else { //define serial connection parameters arduino board dcbserialparams.baudrate=cbr_9600; dcbserialparams.bytesize=8; dcbserialparams.stopbits=onestopbit; dcbserialparams.parity=noparity; //set parameters , check proper application if(!setcommstate(hserial, &dcbserialparams)) { printf("alert: not set serial port parameters"); } else { //if went fine we're connected this->connected = true; //we wait 2s arduino board reseting sleep(arduino_wait_time); } } } } //has if serialport still connected. //if yes, disconnects , closes serial handler. serial::~serial() { //check if connected before trying disconnect if(this->connected) { //we're no longer connected this->connected = false; //close serial handler closehandle(this->hserial); } } // reads data out of serial port int serial::readdata(char *buffer, unsigned int nbchar) { //number of bytes we'll have read dword bytesread; //number of bytes we'll ask read unsigned int toread; //use clearcommerror function status info on serial port clearcommerror( this->hserial, // handle communications device, createfile function returns value &this->errors, // pointer variable receives mask indicating type of rror &this->status);// pointer comstat structure in devices status information returned. if parameter null, no status information returned //check if there read if(this->status.cbinque>0) // cbinque: number of bytes received serial provider, not yet read readfile operation { //if there check if there enough data read required number //of characters, if not we'll read available characters prevent //locking of application. if(this->status.cbinque>nbchar) {toread = nbchar;} else {toread = this->status.cbinque;} //try read require number of chars, , return number of read bytes on success if(readfile( this->hserial, // handle device buffer, // pointer buffer receives data read file or device toread, // numberofbytestoread: maximum number of bytes read &bytesread, // numberofbytesread: pointer variable receives number of bytes read when using synchronours hfile parameter. null) // overlapped && bytesread // value of bytesread after readfile function != 0) {return bytesread; sleep(1000);} // returns value of bytesread } //if nothing has been read, or error detected return -1 return -1; } bool serial::isconnected() // returns connection status { //simply return connection status return this->connected; } main:
// application reads specified serial port , reports collected data int _tmain(int argc, _tchar* argv[]) { printf("welcome serial test app!\n\n"); serial* sp = new serial("\\\\.\\com3"); // adjust needed if (sp->isconnected()) printf("we're connected"); // defines how data catched // don't forget pre-allocate memory char incomingdata[1025] = ""; incomingdata[1024]='\0'; int datalength = 1024; // maximum length of 1 databit/word int readresult = 0; // gives out number! of databits collected/catched readresult = sp->readdata(incomingdata,datalength); printf("bytes read: (-1 means no data available) %i\n",readresult); // transforms char incomingdata string , prints std::string test(incomingdata); printf("%s \n", incomingdata); printf("bytes read: (-1 means no data available) %i\n",readresult); sleep(10000); } so here problem:
the programm works fine, long amount of bits sending arduino less datalength. (here = 1024) got less bits through setting delay arduino programm quite high (~100ms). have console window output similar this:
a a a ... goes on but if arduino sends more 1024 bits (delay ~ 1ms)/ pc receices more bits value of datalength, in serial::readdata loop seems wrong. console output little bit corrupted , bits this:
a ßa a ... goes on similar this. what wrong program? thought be, 1 parameter of readfile() function not right, not know change , not 100% sure this.
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