kivy和串口问题

Question

这些方框代表什么？

从设备文件读取时获得此输出。

我用cutecom和putty检查过。它工作正常。

这是我的代码片段。

def button_on_pressed(self):
    ## try connecting to serial port
    try: 
        ## create an instance of serial port with user specified parameters
        self.port_connected = serial.Serial(port=self.ids.txtinp_1.text,baudrate=int(self.ids.txtinp_2.text),timeout=0)

        self.ids.text_3.text='[color=3333ff][b]successful connected to ' + self.ids.txtinp_1.text + ' ' + self.ids.txtinp_2.text+ '[/color][/b]'
        self.port_connected.write('\n\n\n\n\n\n\n') 
        self.ids.Main_txtinp_1.text = self.readlineCR()
    except serial.SerialException:
        self.ids.text_3.text= '[color=ff3333][size=18][b]Error: device not available[/b][/size][/color]'
    finally:
        pass

def on_enter_txt_input(self,value):
    try:
        self.ids.text_3.text = value
        print value
        self.txt_input_user = value + '\r'
        self.port_connected.write(self.txt_input_user)
        self.ids.Main_txtinp_1.text = ''.join(self.ids.Main_txtinp_1.text + '\r\n' + self.readlineCR())
        self.ids.sub_txtinp.focus = False
        self.ids.sub_txtinp.focus = True
    except :
        self.ids.text_3.text= '[color=ff3333][size=18][b]Error: open device 1st[/b][/size][/color]'
    finally:

        pass



def readlineCR(self):
    rv = ""
    while True:
        ch = self.port_connected.read(1)
        rv += ch
        if ch=='\r' or ch=='':
            return rv