Typeerror: Unicode strings are not supported, please encode to bytes: 'ÿ'

Question

我发现这段代码 (https://drive.google.com/open?id=1TGuTPjfiV4r7ra_5eLMkbXBnesYlvTyT) 由 Adafruit 编写（并由我修改以添加一些在 python 2.7 中工作的额外功能，当我尝试运行 python 3 中的代码使其更易于开发（因为我之前没有看过太多 python 2）它给了我错误：

Traceback (most recent call last):
  File "/home/pi/Forecast-Printer/forecast.py", line 55, in <module>
    printer = Adafruit_Thermal("/dev/serial0", 19200, timeout=5)
  File "/home/pi/Forecast-Printer/Adafruit_Thermal.py", line 95, in __init__
    self.wake()
  File "/home/pi/Forecast-Printer/Adafruit_Thermal.py", line 605, in wake
    self.writeBytes(255)
  File "/home/pi/Forecast-Printer/Adafruit_Thermal.py", line 189, in writeBytes
    super(Adafruit_Thermal, self).write(chr(arg))
  File "/usr/lib/python3/dist-packages/serial/serialposix.py", line 518, in write
    d = to_bytes(data)
  File "/usr/lib/python3/dist-packages/serial/serialutil.py", line 63, in to_bytes
    raise TypeError('unicode strings are not supported, please encode to bytes: {!r}'.format(seq))
TypeError: unicode strings are not supported, please encode to bytes: 'ÿ'

代码是运行 on a raspberry pi 运行ning raspbian (GUI version) 需要运行 with sudo 因为它通过串口与迷你热敏打印机通信。

提前感谢您的帮助:)

编辑：下面是一些代码，当运行 in python 3:

时会触发相同的错误

from Adafruit_Thermal import *

printer = Adafruit_Thermal("/dev/serial0", 19200, timeout=5)

Answer 1

从堆栈跟踪来看，打印机初始化时，Adafruit 库通过串行写入整数 255 来唤醒打印机。它通过在第 189 行调用 Serial class 的 write() 方法（在它自己的 write_bytes() 方法中）来实现：

super(Adafruit_Thermal, self).write(chr(arg))

它能够做到这一点，因为 Adafruit_Thermal class 继承自 Serial，如您在 class 定义中所见。

正如@abarnert 指出的那样，chr() returns 是一个字符串，但听起来 write() 需要二进制数据。因此，我会尝试对您的问题发表评论中的建议。首先尝试将第 189 行更改为：

super(Adafruit_Thermal, self).write(arg)

如果不行试试：

super(Adafruit_Thermal, self).write(bytes([arg]))

Typeerror: Unicode strings are not supported, please encode to bytes: 'ÿ'

Typeerror: Unicode strings are not supported, please encode to bytes: 'ÿ'

python

python-2.7

python-3.x

raspberry-pi

raspbian