Fixing escaped characters python-xbee

[pabloblo85]

I am using a XBee to receive data from an arduino network.

But they have AP=2 which means escaped characters are used when a 11 or 13 
appears (and some more...)

When this occurs, XBee sends 7D and inmediatly XOR operation with char and 0x20.

I am trying to recover the original character in python but I don't know ho to 
do it.

I tried something like this:

read = ser.read(4) #Read 4 chars from serial port
for x in range (0,4):
if(toHex(read[x]) != '7d'): #toHex converts it to hexadecimal 
just for checking purposes
if(x < 3):
read[x] = logical_xor(read[x+1], 20) #XOR
for y in range (x+1,3):
read[y] = read[y+1] 

read[3] = ser.read()
else:
read[x] = logical_xor(ser.read(), 20) #XOR

data = struct.unpack('http://mail.python.org/mailman/listinfo/python-list

Re: Fixing escaped characters python-xbee

[pabloblo85]

> 
> the following in gmane.comp.python.general:
> 
> 
> 
> > I am using a XBee to receive data from an arduino network.
> 
> > 
> 
> > But they have AP=2 which means escaped characters are used when a 11 or 13 
> > appears (and some more...)
> 
> > 
> 
> > When this occurs, XBee sends 7D and inmediatly XOR operation with char and 
> > 0x20.
> 
> > 
> 
> > I am trying to recover the original character in python but I don't know ho 
> > to do it.
> 
> > 
> 
> > I tried something like this:
> 
> > 
> 
> > read = ser.read(4) #Read 4 chars from serial port
> 
> 
> 
>   Why read 4 at a time if you need to detect the escape marker...
> 
> 
> 
> PSEUDO_CODE -- UNTESTED:
> 
> 
> 
>   for c in ser.read():#presumes it will function as an iterator
> 
>   if ord(c) == 0x7D:
> 
>   c =chr(ord(ser.read(1)) ^ 0x20)
> 
>   #do something with c (save to a list for later joining as a
> 
> string?)
> 
>   #probably need some condition to exit the read loop too
> 
> > def logical_xor(str1, str2):
> 
> > return bool(str1) ^ bool(str2)
> 
> >
> 
>   bool() returns True or False based on the argument... Any non-empty
> 
> string will be True. Instead what you want is to x-or the bits of the
> 
> character itself.
> 
> -- 

It works! Thank you so much. Now I can go ahead with my work!
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