Implementation of Windows CE Serial Communication

Serial Communication is currently the most basic communication mode in the computer, communication and control fields. But what kind of serial communication is used? Generally, we provide you with an SDK example program for the Pocket PC 2002. But in the end, the SDK program and the structure of the MFC are very different. It is not very convenient for people who want to use the MFC to write communication programs.

On the other hand, because Windows CE is a Unicode-based operating system, and Windows CE does not support the commonly used serial communication overlapped I/O mode in windows ), therefore, the serial communication classes under Windows CE are different from those on Windows.

The following is the MFC class I have adapted from the SDK program. I hope to have a lot of exchanges with my friends who are dedicated to developing the SDK program. Due to my lack of learning skills, there are many imperfections in the program. please correct me. My program is based on the assumption of "actively sending requests and passively receiving responses", so I only set a thread to receive data. I would be very grateful if a friend can provide classes that independently send data and receive data threads.

Header file serial. h

// Serial. h: interface for the cserial class. // //////////////////////////////////////// ////////////////////////////// # If! Defined (afx_serial_hsf-59575586_aaa9_4fef_b2a7_e089554178ef1_included _) # Define afx_serial_hsf-59575586_aaa9_4fef_b2a7_e089554178ef1_encoded _ # If _ msc_ver> 1000 # Pragma once # Endif // _ msc_ver> 1000 DWORD winapi readportthread (lpvoid); // read data thread Class cserial { Public: Bool initcommtimeouts (); // you can specify the timeout parameter. Bool initdcb (); // configure the serial port Bool m_bconnected; Bool closeport (handle hcommp ORT); // close the serial port DWORD writeport (tchar * Buf, DWORD dwbytestowrite); // write data Bool openport (lptstr lpszportname); // open the serial port Cserial (); Handle hreadthread; Virtual ~ Cserial (); }; # Endif //! Defined (afx_serial_hsf-59575586_aaa9_4fef_b2a7_e089554178ef1_included _) Source File: Serial. cpp // Serial. cpp: Implementation of the cserial class. // //////////////////////////////////////// ////////////////////////////// # Include "stdafx. H" # Include "Serial. H" # Ifdef _ debug # UNDEF this_file Static char this_file [] =__ file __; # Define new debug_new # Endif Handle hport; Cstring strinchar; //////////////////////////////////////// ////////////////////////////// // Construction/destruction //////////////////////////////////////// ////////////////////////////// Cserial: cserial () { } Cserial ::~ Cserial () { If (hport! = Invalid_handle_value) Closeport (hport ); } Bool cserial: openport (lptstr lpszportname) { DWORD dwerror, Dwthreadid; If (hport) { Return false; } // Open the serial port Hport = createfile (lpszportname, generic_read | generic_write, 0, null, open_existing, 0, null ); // If an error occurs while enabling the port, false is returned. If (hport = invalid_handle_value) { // The port cannot be opened Cstring strerror; Strerror. Format (_ T ("unable to open % s, error no. = % d "), Lpszportname, getlasterror ()); MessageBox (null, strerror, text ("error"), mb_ OK ); Return false; } // Event set monitored by the specified port Setcommmask (hport, ev_rxchar ); // Allocate the device Buffer 　 Setupcomm (hport 512,512 ); // Initialize the information in the buffer. Purgecomm (hport, purge_txclear | purge_rxclear ); // Configure the serial port If (! Initdcb ()) Return false; // Set the port timeout value If (! Initcommtimeouts ()) Return false; // Set the status of the specified signal on the port // Setdtr: Send DTR (data-terminal-ready) signals // Setrts: send the request-to-Send signal. Escapecommfunction (hport, setdtr ); Escapecommfunction (hport, setrts ); // Create a thread for reading data from the serial port If (hreadthread = createthread (null, 0, readportthread, 0, 0, & dwthreadid )) { } Else { // The thread cannot be created. MessageBox (null, text ("unable to create the read thread "), Text ("error"), mb_ OK ); Dwerror = getlasterror (); Return false; } M_bconnected = true; Return true; } DWORD cserial: writeport (tchar * Buf, DWORD dwchartowrite) { Bool fwritestate; DWORD dwbyteswritten; // Write data Fwritestate = writefile (hport, Buf, dwchartowrite * sizeof (tchar), & dwbyteswritten, null ); If (! Fwritestate) { // Data cannot be written. MessageBox (null, text ("can't write string to comm"), text ("error"), mb_ OK ); Dwbyteswritten = 0; } Return dwbyteswritten; } DWORD winapi readportthread (lpvoid) { Bool freadstate; DWORD dwcommmodemstatus; DWORD dwlength; COMSTAT; DWORD dwerrorflags; While (hport! = Invalid_handle_value) { // Wait for the serial port event to occur Waitcommevent (hport, & dwcommmodemstatus, 0 ); If (dwcommmodemstatus & ev_rxchar) { Clearcommerror (hport, & dwerrorflags, & COMSTAT ); // Cbinque returns the number of characters in the serial driver input queue Dwlength = COMSTAT. cbinque; If (dwlength> 0) { // Read data from the serial port Tchar * Buf = new tchar [256]; Freadstate = readfile (hport, Buf, dwlength, & dwlength, null ); If (! Freadstate) { // Data cannot be read from the serial port MessageBox (null, text ("error in read from serial port"), text ("read error"), mb_ OK ); } Else { // Assign a value to the global variable Strinchar = Buf; } Delete [] Buf; } } Getcommmodemstatus (hport, & dwcommmodemstatus ); } Return 0; } 　 Bool cserial: closeport (handle hcommp ORT) { If (hcommp ORT! = Invalid_handle_value) { // Set the connection property to false M_bconnected = false; // Waitcommevent waiting in the queue Setcommmask (hport, 0 ); // The thread stops. If (hreadthread) { Terminatethread (hreadthread, 0 ); Closehandle (hreadthread ); } // Clear the status of the specified signal on the port Escapecommfunction (hport, clrdtr ); Escapecommfunction (hport, clrrts ); // Clear the internal sending and receiving queues of the driver Purgecomm (hport, purge_txclear | purge_rxclear ); // Close the serial port Closehandle (hcommp ORT ); Hcommp ORT = invalid_handle_value; Return true; } Else { Return true; } } Bool cserial: initdcb () { DCB portdcb; DWORD dwerror; 　　 Portdcb. dcblength = sizeof (DCB ); // Obtain the default port settings. Getcommstate (hport, & portdcb ); // Change the DCB structure settings Portdcb. baudrate = 19200; // baud rate Portdcb. fbinary = true; // Win32 does not support non-binary serial transmission mode, which must be true Portdcb. fparity = true; // enable parity Portdcb. foutxctsflow = true; // the output of the serial port is controlled by the CTS line. Portdcb. foutxdsrflow = false; // disable the DSR Flow Control of the serial port. Portdcb. fdtrcontrol = dtr_control_enable; // enables the DTr line. Portdcb. fdsrsensitivity = false; // If set to true, any input bytes are ignored unless the DSR line is enabled. // Portdcb. ftxcontinueonxoff = true; // if the value is true, if the receiving buffer is full and the driver has transferred xoff characters, the driver stops transmitting characters. Portdcb. ftxcontinueonxoff = false; Portdcb. foutx = false; // set to true specify that the Xon/xoff control is used to control the serial output. Portdcb. finx = false; // set to true specify that the Xon/xoff control is used to control serial input. Portdcb. ferrorchar = false; // The default execution of the wince serial driver ignores this field. Portdcb. fnull = false; // if it is set to true, the serial driver ignores the NULL bytes received. Portdcb. frtscontrol = rts_control_enable; // enables the RTS line. Portdcb. fabortonerror = false; // The default execution of the wince serial driver ignores this field. Portdcb. bytesize = 8; // The number of digits per byte Portdcb. Parity = noparity; // No parity Portdcb. stopbits = onestopbit; // One Stop bit per byte // Configure the port according to the DCB Structure If (! Setcommstate (hport, & portdcb )) { // The serial port cannot be configured. MessageBox (null, text ("unable to configure the serial port"), text ("error"), mb_ OK ); Dwerror = getlasterror (); Return false; } Return true; } Bool cserial: initcommtimeouts () { Commtimeouts; DWORD dwerror; // Get the timeout Parameter Getcommtimeouts (hport, & commtimeouts ); // Change the commtimeouts structure settings Commtimeouts. readintervaltimeout = maxdword; Commtimeouts. readtotaltimeoutmultiplier = 0; Commtimeouts. readtotaltimeoutconstant = 0; Commtimeouts. writetotaltimeoutmultiplier = 10; Commtimeouts. writetotaltimeoutconstant = 1000; // Set the port timeout value If (! Setcommtimeouts (hport, & commtimeouts )) { // The timeout value cannot be set. MessageBox (null, text ("unable to set the time-out parameters"), text ("error"), mb_ OK ); Dwerror = getlasterror (); Return false; } Return true; }

The above code was tested and passed on Embedded Visual C ++ 4.0 and Samsung S3C2410 Development Board (running Windows CE. Net 4.1) based on ARM9.