esptool.py 文件源码

def command(self, op=None, data=None, chk=0):
        if op is not None:
            pkt = struct.pack('<BBHI', 0x00, op, len(data), chk) + data
            self.write(pkt)

        # tries to get a response until that response has the
        # same operation as the request or a retries limit has
        # exceeded. This is needed for some esp8266s that
        # reply with more sync responses than expected.
        for retry in xrange(100):
            p = self.read()
            if len(p) < 8:
                continue
            (resp, op_ret, len_ret, val) = struct.unpack('<BBHI', p[:8])
            if resp != 1:
                continue
            body = p[8:]
            if op is None or op_ret == op:
                return val, body  # valid response received

        raise FatalError("Response doesn't match request")