我正在编写一个应用程序，可以从Mac Mini的桌面控制投影机。我正在使用Xcode和termios.h在Objective-C中编写应用程序来与串口通信。我从USB转串口适配器连接，我知道驱动程序安装正确，因为我可以向投影机发送HEX命令来控制其功能。
我写的代码我认为应该打开串口，连接到投影仪，发送代码并断开连接：
@implementation Projector
@synthesize helpUrl = _helpUrl;
@synthesize projectorConnected;
- (id)init {
//[self connectProjector];
if (TRUE == projectorConnected) {
// Success!
}
else {
// Error!
}
return self;
}
- (id)initWithHelpUrl:(NSString *)helpUrlString {
[self setHelpUrl:helpUrlString];
return [self init];
}
- (void)connectProjector {
[self setProjectorConnected:FALSE];
NSString *deviceNameString = @"/dev/tty.usbserial";
speed_t baudRate = B19200;
serialFileDescriptor = [self openSerialPort:[deviceNameString cStringUsingEncoding:NSASCIIStringEncoding] baud:baudRate];
if (serialFileDescriptor == -1) {
NSLog(@"Error opening serial port file!");
}
_fileHandle = [[NSFileHandle alloc] initWithFileDescriptor: serialFileDescriptor];
//[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(receiveSerialMessage:) name:NSFileHandleReadCompletionNotification object:_fileHandle];
//[_fileHandle readInBackgroundAndNotify];
// [self closeSerialPort];
}
- (int)openSerialPort:(const char *)serialPortFile baud:(speed_t)baudRate {
struct termios toptions;
int fd;
fd = open(serialPortFile, O_RDWR | O_NOCTTY | O_NDELAY);
if (fd == -1) {
perror("init_serialport: Unable to open port ");
return -1;
}
if (tcgetattr(fd, &gOriginalTTYAttrs) < 0) {
perror("init_serialport: Couldn't get term attributes");
return -1;
}
toptions = gOriginalTTYAttrs;
cfsetispeed(&toptions, baudRate);
cfsetospeed(&toptions, baudRate);
toptions.c_cflag &= PARENB;
toptions.c_cflag &= CSTOPB;
toptions.c_cflag &= CSIZE;
toptions.c_cflag |= CS8;
toptions.c_cflag &= CRTSCTS;
toptions.c_cflag |= CREAD | CLOCAL;
toptions.c_iflag &= (IXON | IXOFF | IXANY);
toptions.c_lflag &= (ICANON | ECHO | ECHOE | ISIG);
toptions.c_oflag &= OPOST;
// see: http://unixwiz.net/techtips/termios-vmin-vtime.html
toptions.c_cc[VMIN] = 0;
toptions.c_cc[VTIME] = 20;
if( tcsetattr(fd, TCSANOW, &toptions) < 0) {
perror("init_serialport: Couldn't set term attributes");
return -1;
}
return fd;
}
- (void)sendSerialMessage:(NSString *)message {
NSString *deviceNameString = @"/dev/tty.usbserial";
speed_t baudRate = B19200;
serialFileDescriptor = [self openSerialPort:[deviceNameString cStringUsingEncoding:NSASCIIStringEncoding] baud:baudRate];
if (serialFileDescriptor == -1) {
NSLog(@"Error opening serial port file!");
}
_fileHandle = [[NSFileHandle alloc] initWithFileDescriptor: serialFileDescriptor];
//[[NSNotificationCenter defaultCenter] addObserver:self selector:@selector(receiveSerialMessage:) name:NSFileHandleReadCompletionNotification object:_fileHandle];
//[_fileHandle readInBackgroundAndNotify];
// convert message string into NSData
NSString *dataString = [message stringByReplacingOccurrencesOfString:@" " withString:@""];
NSMutableData *dataToSend = [[NSMutableData alloc] init];
unsigned char whole_byte;
char byte_chars[3] = {'\0','\0','\0'};
int i;
for (i=0; i < 6; i++) {
byte_chars[0] = [dataString characterAtIndex:i*2];
byte_chars[1] = [dataString characterAtIndex:i*2+1];
whole_byte = strtol(byte_chars, NULL, 16);
[dataToSend appendBytes:&whole_byte length:1];
}
// write to the serial port file
[_fileHandle writeData:dataToSend];
sleep(10);
[self closeSerialPort];
}
- (void)receiveSerialMessage:(NSNotification *)notification {
NSData* messageData = [[notification userInfo] objectForKey:NSFileHandleNotificationDataItem];
if ( [messageData length] == 0 ) {
[_fileHandle readInBackgroundAndNotify];
return;
}
NSString* receivedMessage = [[NSString alloc] initWithData:messageData encoding:NSASCIIStringEncoding];
[[NSNotificationCenter defaultCenter] postNotificationName:@"serialMessageReceived" object:receivedMessage];
[_fileHandle readInBackgroundAndNotify];
}
// Given the file descriptor for a serial device, close that device.
- (void)closeSerialPort {
///*
// Block until all written output has been sent from the device.
// Note that this call is simply passed on to the serial device driver.
// See tcsendbreak(3) ("man 3 tcsendbreak") for details.
if (tcdrain(serialFileDescriptor) == -1) {
NSLog(@"Error waiting for drain - %s(%d).", strerror(errno), errno);
}
// Traditionally it is good practice to reset a serial port back to
// the state in which you found it. This is why the original termios struct
// was saved.
if (tcsetattr(serialFileDescriptor, TCSANOW, &gOriginalTTYAttrs) == -1) {
NSLog(@"Error resetting tty attributes - %s(%d).\n", strerror(errno), errno);
}
//*/
close(serialFileDescriptor);
serialFileDescriptor = -1;
_fileHandle = nil;
}
- (BOOL)powerOn {
[self sendSerialMessage:@"02 00 00 00 00 02"];
// TODO: change to success/failure
return TRUE;
}
- (BOOL)powerOff {
[self sendSerialMessage:@"02 01 00 00 00 03"];
// TODO: change to success/failure
return TRUE;
}
- (BOOL)blankScreen {
[self sendSerialMessage:@"02 10 00 00 00 12"];
// TODO: change to success/failure
return TRUE;
}
- (BOOL)showScreen {
[self sendSerialMessage:@"02 11 00 00 00 13"];
// TODO: change to success/failure
return TRUE;
}
- (BOOL)requestHelp {
NSURLRequest *request = [NSURLRequest requestWithURL:[NSURL URLWithString:_helpUrl]];
// Perform request and get data back
NSData *responseData = [NSURLConnection sendSynchronousRequest:request returningResponse:nil error:nil];
if (nil != responseData) {
// TODO change this to check for response code is 200?
return TRUE;
/*
// get String value of response
NSString *returnString = [[NSString alloc] initWithData:responseData encoding:NSUTF8StringEncoding];
// DEBUG
NSLog(@"Return string: %@", returnString);
// TODO: better way to do this?
NSString *successString = @"{\"status\":true}";
if ([returnString isEqualToString:successString]) {
// success
NSLog(@"Success!");
return TRUE;
}
else {
NSLog(@"Error bad response");
}
*/
}
else {
NSLog(@"Error: no response");
}
// return faliure!
return FALSE;
}
@end
我想知道我哪里出错了，因为当我运行该程序时，它会挂起。
答案 0 :(得分：1)
我看到了Prolific的USB转串口适配器驱动程序的严重问题，特别是在Mac OS X Lion下。您可以尝试此alternative driver它基于osx-pl2303开源驱动程序代码。
就个人而言，我建议使用不同的USB转串口适配器。我喜欢Keyspan的USA-19HS适配器，并且在任何版本的Mac OS X上都没有遇到过驱动程序的问题。我也听说过有关FTDI的好消息，但没有基于该芯片组的适配器的个人经验。
有关此问题的详情，请参阅我的earlier question。