I am trying serial communication with my Arduino by C using win32api. I can write and read data but reading is very slowly (Actually after Characters Received message). After characters received the message it takes 7-8 seconds to show the result (this program send a number to Arduino and get square).
Initial/Setup codes:
#include <stdio.h>
#include <stdlib.h>
#include <Windows.h>
#include <conio.h>
#include <string.h>
int main(int argc, char *argv[]) {
HANDLE hComm; // Handle to the Serial port
char ComPortName[] = "\\.\COM4"; // Name of the Serial port(May Change) to be opened,
BOOL Status;
DWORD dwEventMask;
char TempChar;
DWORD NoBytesRead;
char SerialBuffer[256];
int i = 0;
/*----------------------------------- Opening the Serial Port --------------------------------------------*/
hComm = CreateFile(ComPortName, // Name of the Port to be Opened
GENERIC_READ | GENERIC_WRITE, // Read/Write Access
0, // No Sharing, ports cant be shared
NULL, // No Security
OPEN_EXISTING, // Open existing port only
0, // Non Overlapped I/O
NULL); // Null for Comm Devices
/*if (hComm == INVALID_HANDLE_VALUE)
printf("
Error! - Port %s can't be opened", ComPortName);
else
printf("
Port %s Opened
", ComPortName);*/
/*------------------------------- Setting the Parameters for the SerialPort -----------------------*/
DCB dcbSerialParams = {0}; // Initializing DCB structure
dcbSerialParams.DCBlength = sizeof(dcbSerialParams);
Status = GetCommState(hComm, &dcbSerialParams); //retreives the current settings
/*if (Status == FALSE)
printf("
Error! in GetCommState()");*/
dcbSerialParams.BaudRate = CBR_9600; // Setting BaudRate = 9600
dcbSerialParams.ByteSize = 8; // Setting ByteSize = 8
dcbSerialParams.StopBits = ONESTOPBIT; // Setting StopBits = 1
dcbSerialParams.Parity = NOPARITY; // Setting Parity = None
Status = SetCommState(hComm, &dcbSerialParams); //Configuring the port according to settings in DCB
/*if (Status == FALSE)
{
printf("
Error! in Setting DCB Structure");
}
else
{
printf("
Setting DCB Structure Successfull
");
printf("
Baudrate = %d", dcbSerialParams.BaudRate);
printf("
ByteSize = %d", dcbSerialParams.ByteSize);
printf("
StopBits = %d", dcbSerialParams.StopBits);
printf("
Parity = %d", dcbSerialParams.Parity);
}*/
/*------------------------------------ Setting Timeouts --------------------------------------------------*/
COMMTIMEOUTS timeouts;
timeouts.ReadIntervalTimeout = 0;
timeouts.ReadTotalTimeoutConstant = 0;
timeouts.ReadTotalTimeoutMultiplier = 1;
timeouts.WriteTotalTimeoutConstant = 0;
timeouts.WriteTotalTimeoutMultiplier = 0;
/*if (SetCommTimeouts(hComm, &timeouts) == FALSE)
printf("
Error! in Setting Time Outs");
else
printf("
Setting Serial Port Timeouts Successfull");*/
Body codes:
char squareNumber[10];
int clickedCount;
while(1){
printf("Enter number to find square : ");
scanf("%s",&squareNumber); // get number from user
int count = strlen(squareNumber);
writeData(squareNumber,Status,hComm,count); // send data func
getData(Status , hComm , dwEventMask, TempChar,NoBytesRead,SerialBuffer,I); // get data func
getch();
}
writeData func:
void writeData(char data[] , BOOL Status , HANDLE hComm , int count){
/*----------------------------- Writing a Character to Serial Port--------------------------------*/
char lpBuffer[count]; // lpBuffer should be char or byte array, otherwise write wil fail
memcpy(lpBuffer, data,count);
DWORD dNoOFBytestoWrite; // No of bytes to write into the port
DWORD dNoOfBytesWritten = 0; // No of bytes written to the port
dNoOFBytestoWrite = sizeof(lpBuffer); // Calculating the no of bytes to write into the port
Status = WriteFile(hComm, // Handle to the Serialport
lpBuffer, // Data to be written to the port
dNoOFBytestoWrite, // No of bytes to write into the port
&dNoOfBytesWritten, // No of bytes written to the port
NULL);
/*if (Status == TRUE)
printf("
%s - Written to %s", lpBuffer, ComPortName);
else
printf("
Error %d in Writing to Serial Port", GetLastError());*/
}
getData func:
void getData(BOOL Status , HANDLE hComm, DWORD dwEventMask , char TempChar, DWORD NoBytesRead, char
SerialBuffer[],int i){
/*------------------------------------ Setting Receive Mask --------------------------------------*/
Status = SetCommMask(hComm, EV_RXCHAR); //Configure Windows to Monitor the serial device for
Character Reception
if (Status == FALSE)
printf("
Error! in Setting CommMask");
else
printf("
Setting CommMask successfull");
/*------------------------------------ Setting WaitComm() Event --------------------------------*/
printf("
Waiting for Data Reception");
Status = WaitCommEvent(hComm, &dwEventMask, NULL); //Wait for the character to be received
/*-------------------------- Program will Wait here till a Character is received ------------------------*/
if (Status == FALSE)
{
printf("
Error! in Setting WaitCommEvent()");
}
else
//If WaitCommEvent()==True Read the RXed data using ReadFile();
{
printf("
Characters Received");
do
{
Status = ReadFile(hComm, &TempChar, sizeof(TempChar), &NoBytesRead, NULL);
SerialBuffer[i] = TempChar;
i++;
} while (NoBytesRead > 0); //!!!Probably bug is here
/*------------Printing the RXed String to Console----------------------*/
printf("
");
int j = 0;
for (j = 0; j < i - 1; j++) // j < i-1 to remove the dupliated last character
printf("%c", SerialBuffer[j]);
}
}
Arduino codes:
void setup() {
pinMode(13, OUTPUT);
pinMode(12, OUTPUT);
Serial.begin(9600);
Serial.setTimeout(1000);
}
void loop() {
if (Serial.available() > 0) {
incomingByte = Serial.read();
int variable = Serial.parseInt();
Serial.print("Square : ");
Serial.print(variable*variable);
}
}
question from:
https://stackoverflow.com/questions/65835829/serial-communication-read-serial-is-very-low-in-c 
