OK, I'll try to explain everything.
I want to design block responsible for decoding messages, calculating crc,
etc ... In order to do that I investigated packet_demod_base block from
main gnuradio branch,
and also packet_deframer from gr_extras group of blocks. I realized that
such kind of blocks consists of correlator, framer sink which acts like
message sink, and finally of some kind of message source. Framer sink sends
messages to message
source and message source then does packet checking and everything.
I also wanted to design my block in that fashion, so I used correlator and
framer sink and I wanted to design my own block which is able to receive
messages from packet framer and to check it. The code I provided in the
last post is my own, and not the part of gnuradio. Here is complete source
file of my block:
import numpy
from math import pi
from gnuradio import gr
from gruel import pmt
from gnuradio.digital import packet_utils
import gnuradio.digital as gr_digital
class packet_tst(gr.hier_block2):
def __init__(self, access_code=None, threshold=-1):
gr.hier_block2.__init__(
self,
"packet_tst",
gr.io_signature(1, 1, 1), # Input signature
gr.io_signature(0, 0, 0) # Output signature
)
if not access_code:
access_code = packet_utils.default_access_code
if not packet_utils.is_1_0_string(access_code):
raise ValueError, "Invalid access_code %r. Must be string of
1's and 0's" % (access_code,)
if threshold == -1:
threshold = 12 # FIXME raise exception
msgq = gr.msg_queue(4) # holds packets from the PHY
self.correlator = gr_digital.correlate_access_code_bb(access_code,
threshold)
self.framer_sink = gr.framer_sink_1(msgq)
self.connect(self, self.correlator, self.framer_sink)
self.hlp_blk = helper_block(msgq)
class helper_block(gr.basic_block):
def __init__(self, msgq):
gr.basic_block.__init__(
self, name = "helper_block",
in_sig = None, out_sig = None
# num_msg_outputs = 1
)
self._msgq = msgq
def work(self, input_items, output_items):
while True:
try: msg = self._msgq.delete_head()
except: return -1
print "Message received"
At the moment the block is designed only to write something to standard
output if it receives a message. The problem is gr.basic_block as I
described in previous post. Python interpreter doesn't complain about
gr.hier_block2, but only about gr.basic_block.
The tutorial for writing blocks in python is from gnuradio.org:
http://gnuradio.org/redmine/projects/gnuradio/wiki/OutOfTreeModules#Tutorial-3-Writing-a-signal-processing-block-in-Python
Hope this helps.
Thanks
On Tue, Jan 29, 2013 at 2:16 PM, Tom Rondeau <t...@trondeau.com> wrote:
> On Tue, Jan 29, 2013 at 7:40 AM, Nemanja Savic <vlasi...@gmail.com> wrote:
>
>> I'm not sure what you mean by "load gr.basic_block." Do you mean inherit
>>> from?
>>
>>
>> I want to make my block which very similar to packet deframer. Here is th
>> code:
>>
>> class packet_tst(gr.hier_block2):
>>> def __init__(self, access_code=None, threshold=-1):
>>>
>>> gr.hier_block2.__init__(
>>> self,
>>> "packet_tst",
>>> gr.io_signature(1, 1, 1), # Input signature
>>> gr.io_signature(0, 0, 0) # Output signature
>>> )
>>>
>>> if not access_code:
>>> access_code = packet_utils.default_access_code
>>> if not packet_utils.is_1_0_string(access_code):
>>> raise ValueError, "Invalid access_code %r. Must be string of
>>> 1's and 0's" % (access_code,)
>>>
>>> if threshold == -1:
>>> threshold = 12 # FIXME raise exception
>>>
>>> msgq = gr.msg_queue(4) # holds packets from the PHY
>>> self.correlator =
>>> gr_digital.correlate_access_code_bb(access_code, threshold)
>>>
>>> self.framer_sink = gr.framer_sink_1(msgq)
>>> self.connect(self, self.correlator, self.framer_sink)
>>>
>>> self.hlp_blk = helper_block(msgq)
>>>
>>
>> in the same file is also defined class helper_block in this way:
>>
>> class helper_block(gr.basic_block):
>>> def __init__(self, msgq):
>>> gr.basic_block.__init__(
>>> self, name = "helper_block",
>>> in_sig = None, out_sig = None
>>> # num_msg_outputs = 1
>>> )
>>>
>>> self._msgq = msgq
>>>
>>> def work(self, input_items, output_items):
>>> while True:
>>> try: msg = self._msgq.delete_head()
>>> except: return -1
>>> print "Message received"
>>
>>
> I have no idea what files these are from. Are they part of the GNU Radio
> source code? I can't find references to them.
>
>
>
>> when I try to run test or flowgraph, I get this error:
>>
>> in <module>
>>> class helper_block(gr.basic_block):
>>>
>>> AttributeError: 'module' object has no attribute 'basic_block'
>>> -- Process completed
>>> ***Failed
>>>
>>> 0% tests passed, 1 tests failed out of 1
>>
>>
> Sounds like you don't have something installed correctly. You wouldn't
> normally be inheriting straight from gr_basic_block, but you should be able
> to.
>
>
>> And in tutorial on how to write signal processing block, it is stated to
>> use gr.basic_block.
>>
>
> Which tutorial? Again, I don't think this is in the main GNU Radio source,
> so please point out where you are getting this from.
>
> Tom
>
>
--
Nemanja Savić
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