serial.py 文件源码

def __init__(self, device="/dev/ttyAMA0", baudrate=9600):
        if not device.startswith("/dev/"):
            device = "/dev/%s" % device

        if isinstance(baudrate, str):
            baudrate = int(baudrate)

        aname = "B%d" % baudrate
        if not hasattr(termios, aname):
            raise Exception("Unsupported baudrate")
        self.baudrate = baudrate

        Bus.__init__(self, "UART", device, os.O_RDWR | os.O_NOCTTY)
        fcntl.fcntl(self.fd, fcntl.F_SETFL, os.O_NDELAY)

        #backup  = termios.tcgetattr(self.fd)
        options = termios.tcgetattr(self.fd)
        # iflag
        options[0] = 0

        # oflag
        options[1] = 0

        # cflag
        options[2] |= (termios.CLOCAL | termios.CREAD)
        options[2] &= ~termios.PARENB
        options[2] &= ~termios.CSTOPB
        options[2] &= ~termios.CSIZE
        options[2] |= termios.CS8

        # lflag
        options[3] = 0

        speed = getattr(termios, aname)
        # input speed
        options[4] = speed
        # output speed
        options[5] = speed

        termios.tcsetattr(self.fd, termios.TCSADRAIN, options)