[Tutor] More confusion on conversion

[Lloyd Kvam]

for each in [ hex(ord(x)) for x in '%02X' % length ]:

I used that line in my earlier email.  BUT it can be simplified:

length = 10
for x in '%02X' % length:
     port.write(x)
     time.sleep(.01)
     print '%02X' % ord(x)


Note that '\x30' has the same value as '0'

 >>> print '\x30' == '0'
1

They are just alternate means of writing the same thing.  The '\x30'
emphasizes the bit value.  The '0' is for people to read.

Stanfield, Vicki {D167~Indianapolis} wrote:

> Probably I am the one being dense, but I know that the device on the other end expects what it calls a "hex value represented as ASCII." This means that if I want to send a decimal 10, I first have to convert decimal 10 to hex 'A' and then I have to take the hex of the letter 'A' as if it were ASCII and send that. In this example, I need to send 0x30 0x41 (as two bytes of data). In this example, doing this:
> 
> port.write('\x30')
> port.write('\x41')
> 
> is the equivalent of what I want. Of course, I have to make it handle lengths other than 10 too.
> 
> Is that any clearer?
> 
> --vicki
> 
> -----Original Message-----
> From: Reggie Dugard [mailto:reggie at merfinllc.com]
> Sent: Thursday, October 30, 2003 3:47 PM
> To: Stanfield, Vicki {D167~Indianapolis}
> Cc: tutor at python.org
> Subject: RE: [Tutor] More confusion on conversion
> 
> 
> Vicki,
> 
> Forgive me if I'm being dense, but how many bytes do you want to write
> out on the port for each length?  If the answer is 2, then writing '0'
> and 'A' is equivalent to writing 0 and 65 which is equivalent to writing
> 0x00 and 0x41 - they all have the same bit pattern: 00000000 01000001.
> 
> Sorry if I'm misunderstanding you.
> 
> Reggie
> 
> On Thu, 2003-10-30 at 12:24, Stanfield, Vicki {D167~Indianapolis} wrote:
> 
>>Nope, this write '0A' out one the port. I need to write the hex value of the 0 and then the hex value of the 'A'. WHen I tried this:
>>
>>for each in [ hex(ord(x)) for x in '%02X' % length ]:
>>                    port.write('%02X' %each)
>>                    time.sleep(.01)
>>                    print '%02X' %each
>>
>>It was close, but it wants an integer instead of the hex values.
>>
>>port.write('%02X' %each)
>>TypeError: an integer is required
>>
>>--vicki
>>
>>-----Original Message-----
>>From: Reggie Dugard [mailto:reggie at merfinllc.com]
>>Sent: Thursday, October 30, 2003 3:09 PM
>>To: Stanfield, Vicki {D167~Indianapolis}
>>Cc: tutor at python.org
>>Subject: RE: [Tutor] More confusion on conversion
>>
>>
>>Vicki,
>>
>>If I understand you correctly you simply want something like:
>>
>>	port.write('%02X' % length)
>>
>>This should write 2 bytes on the port, one for each hex digit.  If I'm
>>misunderstanding what you want, maybe you can clarify it a bit more.
>>
>>Also, I'm sending this back to the list so that people more
>>knowledgeable than me can help you out as well.
>>
>>Good luck with your problem.
>>
>>Reggie
> 
> 
> 
> 
> 
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-- 
Lloyd Kvam
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