Debian を実行しているシングル ボード コンピュータに接続された Windows マシンがあり、シリアル ポートを使用してそれらの間でバイトを送受信しようとしています。Windows 側では、私のコードは次のようになります。
// open serial port
HANDLE hSerial;
hSerial = CreateFile ("COM1", GENERIC_READ | GENERIC_WRITE, 0, 0, OPEN_EXISTING, FILE_ATTRIBUTE_NORMAL, 0);
// get serial parameters
DCB dcbSerialParams = {0};
dcbSerialParams.DCBlength = sizeof (dcbSerialParams);
if (!GetCommState(hSerial, &dcbSerialParams)) {
cout << "error getting state\n";
exit(0);
}
// set serial params
dcbSerialParams.BaudRate = CBR_115200;
dcbSerialParams.ByteSize = 8;
dcbSerialParams.StopBits = ONESTOPBIT;
dcbSerialParams.Parity = NOPARITY;
if (!SetCommState (hSerial, &dcbSerialParams)) {
cout << "error setting parameters\n";
exit(0);
}
// set time outs
COMMTIMEOUTS timeouts = {0};
timeouts.ReadIntervalTimeout = 50;
timeouts.ReadTotalTimeoutConstant = 10;
timeouts.ReadTotalTimeoutMultiplier = 10;
timeouts.WriteTotalTimeoutConstant = 10;
timeouts.WriteTotalTimeoutMultiplier = 10;
if (!SetCommTimeouts (hSerial, &timeouts)) {
cout << "problem setting timeout values\n";
exit(0);
} else cout << "timeouts set\n";
unsigned char temp = 0;
bool keepReading = true;
while (keepReading) {
DWORD dwBytesRead = 0;
ReadFile (hSerial, &temp, 1, &dwBytesRead, NULL);
if (1 == dwBytesRead) cout << (unsigned int) temp << " ";
if (255 == temp) keepReading = false;
}
cout << endl;
bool keepWriting = true;
unsigned char send = 0;
while (keepWriting) {
DWORD dwBytesWritten = 0;
WriteFile (hSerial, &send, 1, &dwBytesWritten, NULL);
if (255 == send) keepWriting = false;
send++;
}
Linux側では、次のものがあります。
int fd = open("/dev/ttymxc0", O_RDWR | O_NOCTTY);
struct termios options;
bzero (options, sizeof(options));
options.c_cflag = B115200 | CS8 | CLOCAL | CREAD;
options.c_iflat = IGNPAR;
options.c_oflag = 0;
options.c_lflag = ICANON;
options.c_cc[VMIN] = 1;
options.c_CC[VTIME] = 0;
tcflush (fd, TCIFLUSH);
tcsetattr (fd, ICSANOW, &options);
bool keepWriting = true;
unsigned char send = 0;
while (keepWriting) {
write (fd, &send, 1);
if (255 == send) keepWriting = false;
send++;
}
bool keepReading = true;
while (keepReading) {
unsigned char temp = 0;
int n = read (fd, &temp, 1);
if (-1 == n) {
perror ("Read error");
keepReading = false;
} else if (1 == n) {
cout << temp << " ";
}
if (255 == temp) keepReading = false;
}
cout << endl;
両端でコードを実行すると、while ループの最初のセットは正常に動作し、Windows マシンは 0 から 255 を表示しますread
。要求されたすべてのバイトを書き込んだことを報告します。何が起きてる?