コード例 #1
0
ファイル: rchost.py プロジェクト: amlinux/rcrobot
 def __init__(self, dispatcher, devname):
     "Constructor. devname - serial port devname"
     self.dispatcher = dispatcher
     self.stream = RCSerialStream(devname)
     self._next_pkt_id = 0
コード例 #2
0
ファイル: rchost.py プロジェクト: amlinux/rcrobot
class Host(object):
    "Interface to the hardware"
    def __init__(self, dispatcher, devname):
        "Constructor. devname - serial port devname"
        self.dispatcher = dispatcher
        self.stream = RCSerialStream(devname)
        self._next_pkt_id = 0

    def send_raw(self, buf):
        "Send raw data without any checksuming and headers"
        #print "Sending: %s" % (", ".join(["0x%02x" % a for a in buf]))
        buf = ''.join([chr(a) for a in buf])
        with self.stream.get_writer() as writer:
            writer.write_bytes(buf)
            writer.flush()

    def flush(self):
        self.stream.flush()

    def send(self, pkt):
        "Immediately pushes packet to the serial port"
        buf = [0x5a]
        _crc = 0
        for data in [len(pkt)] + list(pkt):
            if type(data) == str and len(data) == 1:
                data = ord(data)
            _crc = crc(_crc, data)
            buf.append(data)
        buf.append(_crc)
        self.send_raw(buf)

    def loop(self):
        "Infinitely reads serial input and parses packets"
        with self.stream.get_reader() as reader:
            while True:
                # waiting for preamble
                while True:
                    data = ord(reader.read_bytes(1))
                    if data == 0x5a:
                        break
                # reading packet length
                _crc = 0
                pktlen = ord(reader.read_bytes(1))
                _crc = crc(_crc, pktlen)
                # reading packet data
                if pktlen > 0:
                    data = []
                    for d in reader.read_bytes(pktlen):
                        d = ord(d)
                        data.append(d)
                        _crc = crc(_crc, d)
                    # reading CRC
                    _crc = crc(_crc, ord(reader.read_bytes(1)))
                    # checking CRC
                    if _crc == 0:
                        #print "Packet received successfully: %s" % (", ".join(["0x%02x" % d for d in data]))
                        self.dispatcher.receive(data)

    def available(self):
        "Check whether host is available"
        req = HostEchoRequest()
        try:
            return self.dispatcher.request(req, timeout=3)
        except TimeoutError:
            return False

    def calibrate_baudrate(self):
        "Perform baud rate calibration"
        req = BaudRateCalibrationRequest()
        try:
            return self.dispatcher.request(req, timeout=3)
        except TimeoutError:
            raise BaudRateCalibrationError()

    def next_pkt_id(self):
        self._next_pkt_id = (self._next_pkt_id + 1) % 256
        return self._next_pkt_id