Hello guys,
Recently I'm trying to send binary data to arduino with C++, and find that sometimes it works, and sometimes it doesn't. And when I run the exe multiple times, there is a pattern: working ---> not working ---> working .....
I guess this has something to do the buffer, but after trying different methods, I'm still confused by this weird behavior. So I decided to post the code and seek help from you. Thanks!
Enviroment: MingW, Arduino Uno R3
C++ code:
Serial.cpp
#include "Serial.h"
Serial::Serial(void)
{
}
void Serial::ConnectSerial(LPCSTR portName)
{
//We're not yet connected
this->connected = false;
//Try to connect to the given port throuh CreateFile
this->hSerial = CreateFile(portName,
GENERIC_READ | GENERIC_WRITE,
0,
NULL,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
NULL);
//Check if the connection was successfull
if(this->hSerial==INVALID_HANDLE_VALUE)
{
//If not success full display an Error
if(GetLastError()==ERROR_FILE_NOT_FOUND){
//Print Error if neccessary
printf("ERROR: Handle was not attached. Reason: %s not available.\n", portName);
}
else
{
printf("ERROR!!!");
}
}
else
{
//If connected we try to set the comm parameters
DCB dcbSerialParams = {0};
//Try to get the current
if (!GetCommState(this->hSerial, &dcbSerialParams))
{
//If impossible, show an error
printf("failed to get current serial parameters!");
}
else
{
//Define serial connection parameters for the arduino board
dcbSerialParams.BaudRate=CBR_115200;
dcbSerialParams.ByteSize=8;
dcbSerialParams.StopBits=ONESTOPBIT;
dcbSerialParams.Parity=NOPARITY;
//Set the parameters and check for their proper application
if(!SetCommState(hSerial, &dcbSerialParams))
{
printf("ALERT: Could not set Serial Port parameters");
}
else
{
//If everything went fine we're connected
this->connected = true;
//We wait 2s as the arduino board will be reseting
Sleep(ARDUINO_WAIT_TIME);
}
}
}
flush();
}
Serial::~Serial()
{
//Check if we are connected before trying to disconnect
if(this->connected)
{
//We're no longer connected
this->connected = false;
//Close the serial handler
CloseHandle(this->hSerial);
}
}
int Serial::ReadData(char *buffer, unsigned int nbChar)
{
//Number of bytes we'll have read
DWORD bytesRead;
//Number of bytes we'll really ask to read
unsigned int toRead;
//Use the ClearCommError function to get status info on the Serial port
ClearCommError(this->hSerial, &this->errors, &this->status);
//Check if there is something to read
if(this->status.cbInQue>0)
{
//If there is we check if there is enough data to read the required number
//of characters, if not we'll read only the available characters to prevent
//locking of the application.
if(this->status.cbInQue>nbChar)
{
toRead = nbChar;
}
else
{
toRead = this->status.cbInQue;
}
//Try to read the require number of chars, and return the number of read bytes on success
if(ReadFile(this->hSerial, buffer, toRead, &bytesRead, NULL) && bytesRead != 0)
{
return bytesRead;
}
}
//If nothing has been read, or that an error was detected return -1
return -1;
}
bool Serial::WriteData(char *buffer, unsigned int nbChar)
{
DWORD bytesSend;
//Try to write the buffer on the Serial port
if(!WriteFile(this->hSerial, (void *)buffer, nbChar, &bytesSend, 0))
{
//In case it don't work get comm error and return false
ClearCommError(this->hSerial, &this->errors, &this->status);
return false;
}
else
return true;
}
bool Serial::IsConnected()
{
//Simply return the connection status
return this->connected;
}
void Serial::WriteIntData(unsigned int val)
{
union serial_super_data {
unsigned int int_4_bytes;
unsigned char send_byte[4];}
super_data;
super_data.int_4_bytes = val;
for (int i=0; i!=4; ++i){
WriteData((char *)(&(super_data.send_byte[i])), 1);
}
}
void Serial::WriteIntDataArray(int *val, int sz)
{
for (int i=0; i!=sz; ++i) {
WriteIntData(val[i]);
}
}
void Serial::flush()
{
FlushFileBuffers(hSerial);
}
Serial.h
#ifndef SERIAL_H
#define SERIAL_H
#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 about the connection
COMSTAT status;
//Keep track of last error
DWORD errors;
public:
//Initialize Serial communication with the given COM port
Serial(void);
void ConnectSerial(LPCSTR portName);
//Close the connection
//NOTA: for some reason you can't connect again before exiting
//the program and running it again
~Serial();
//Read data in a buffer, if nbChar is greater than the
//maximum number of bytes available, it will return only the
//bytes available. The function return -1 when nothing could
//be read, the number of bytes actually read.
int ReadData(char *buffer, unsigned int nbChar);
//Writes data from a buffer through the Serial connection
//return true on success.
bool WriteData(char *buffer, unsigned int nbChar);
void WriteIntData(unsigned int val);
void WriteIntDataArray(int *val, int sz);
//Check if we are actually connected
bool IsConnected();
void flush(void);
};
#endif // SERIALCLASS_H_INCLUDED
testlibserial.cpp
#include <windows.h>
#include <ctime>
#include "Serial.h"
#include <iostream>
using namespace std;
Serial myserial;
int main(int argc, char* argv[])
{
myserial.ConnectSerial("com5");
Sleep(2);
std::cout << "ready for output" << std::endl;
char dd = getchar();
// ========================
for (int j=0; j!=8; j++) {
myserial.WriteIntData(10);
myserial.flush();
Sleep(1000);
}
return 0;
}
Arduino side:
#include <math.h>
int ledPin = 13;//pin 13 has a LED connected on most arduino boards
unsigned long duration = 0;
/* ====================== */
void setup()
{
pinMode(ledPin, OUTPUT);
/* for (int i=2; i <= 11; i++) { */
/* pinMode(i, OUTPUT); */
/* } */
Serial.begin(115200);
/* while (Serial.available()) */
/* Serial.read(); */
}
void loop()
{
while (Serial.available() >= 4) {
receiveBinary(&duration);
if (duration==10)
{
digitalWrite(ledPin, HIGH);
delay(100);
digitalWrite(ledPin, LOW);
}
else {
digitalWrite(ledPin, HIGH);
delay(1000);
digitalWrite(ledPin, LOW);
}
}
}
void receiveBinary(unsigned long *val)
{
union {
unsigned char b[4];
unsigned long longdata;
} foo;
foo.b[0] = Serial.read();
foo.b[1] = Serial.read();
foo.b[2] = Serial.read();
foo.b[3] = Serial.read();
*val = foo.longdata;
}