Converting python2 byte/string encoding to python3

Question

I'm communicating over a serial port, and currently using python2 code which I want to convert to python3. I want to make sure the bytes I send over the wire are the same, but I'm having trouble verifying that that's the case.

In the original code the commands are sent like this:

serial.Serial().write("\xaa\xb4" + chr(2))

If I print "\xaa\xb4" in python2 I get this: ��.
If I print("\xaa\xb4") in python3 I get this: ª´

Encoding and decoding seem opposite too:

Python2: print "\xaa".decode('latin-1') -> ª
Python3: print("\xaa".encode('latin-1')) -> b'\xaa'

To be crude, what do I need to send in serial.write() in python3 to make sure exactly the same sequence of 1s and 0s are sent down the wire?

Ignacio Vazquez-Abrams · Accepted Answer · 2017-10-14 09:08:24Z

1

Use a bytes sequence.

ser.write(b'\xaa\xb4')

answered Oct 14, 2017 at 9:08

Ignacio Vazquez-Abrams

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3 Comments

thosphor Over a year ago

But if I construct the command like this: a = '\xaa', how would I pass that to write()? print(bytes(a, 'utf8')) -> b'\xc2\xaa'

Ignacio Vazquez-Abrams Over a year ago

Normally you wouldn't; you'd use bytes in the first place. If for some reason you have text and you need to convert the first 256 characters to bytes then you can use the latin-1 codec.

thosphor Over a year ago

Yea thanks. Constructing with b'\xaa' and so on has made everything easier. I've realised my problem is with chr() and ord().

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