Thanks for your answers guys,
testing the Dennis answer, and after read the struct information,i reached
a solution:
if i use -> struct.pack('B',255)
now only use one byte on serial communication, instead of 3 bytes like i
was doing before(sending a string '255')
But after some tests, i confirmed if i use the hex string directly on
write. its works too.
Ex:: serial.write('\xFF')
Thanks again for the answers, and sorry for being newbie.
Best Regards,
David
2017-03-09 14:57 GMT+00:00 Dennis Lee Bieber <[email protected]>:
> On Thu, 9 Mar 2017 04:34:43 -0800 (PST),
> [email protected] declaimed the
> following:
>
> >
> >I want to know this because, PySerial only communicate with "string", and
> i
>
> It sends bytes (at least, in Python 2.x -- not sure if Python 3.x
> uses
> unicode or byte as the native component for PySerial), packaged in a Python
> string data type.
>
> There is no constraint on what those bytes contain, beyond that
> imposed
> by the console (console output -- print theString -- may try to convert
> non-ASCII values to something unusable).
>
> >
> >Saying this, i want to send data in int/hex or binary format instead of
> >string from the BeagleBone side, other solution can be change the PySerial
> >module to do this.
> >
>
> "hex" is, to most people, a character string representation of a
> binary
> value using a radix of 16 -- which means each byte of the raw data is
> represented by two characters, one for each four bits.
>
> >Any help will be aprecciated.
>
> Read the library reference manual section describing the struct
> module.
>
>
> >>> import struct
> >>> it = 202
> >>> bt = "6"
> >>> ft = 3.14159
> >>> pck = struct.pack("!hiqBBifd",
> ... it, it, it, it, ord(bt), ord(bt), ft, ft)
> >>>
> >>> repr(pck)
> "'\\x00\\xca\\x00\\x00\\x00\\xca\\x00\\x00\\x00\\x00\\x00\\
> x00\\x00\\xca\\xca6\\x00\\x00\\x006@I\\x0f\\xd0@\\t!\\xf9\\
> xf0\\x1b\\x86n'"
> >>>
>
>
> The format string is (repr() shows each byte, and if printable,
> does
> not show the xNN format):
>
> ! network byte order
> h (signed) short 202 => x00ca
> i (signed) integer 202 => x000000ca
> q (signed) long-long 202 => x00000000000000ca
> B unsigned char (integer data type -- "c" is 1-character string) 202
> =>
> xca
> B unsigned char (need ord() to get integer) ord("6")
> => 54 => '6'
> i (signed) integer ord("6") => 54 =>
> x00 and '6'
> f float 3.14159 => '@I'
> and x04d0
> d double 3.14159 =>
> '@' and <tab> and '!' and xf9f01b86 and 'n'
>
>
> --
> Wulfraed Dennis Lee Bieber AF6VN
> [email protected] HTTP://wlfraed.home.netcom.com/
>
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