ha! uhd.tune_request (and others, like sensor_value) python objects have
a __nonzero__ method, which is inherently used for conversion to bool,
if present. And guess what: they return False.
Wondering where they come from.
Cheers,
Marcus
On 22.05.2016 18:02, Marcus Müller wrote:
> Well, the python semantics, at least as I understand them, dictate
> that "not objectname" is True if objectname is of NoneType, or if
> objectname is actually False, or evaluates to something that is False
> (i.e. 0).
>
> A valid object "should be".
>
> Checking it against the typical swigged GNU Radio objects:
>
> $from gnuradio import blocks, uhd
> $vs = blocks_vector_sink_b()
> $f = uhd.tune_request(10)
> $bool(vs)
> True
> $bool(f)
> False
>
> That's non-uniform behaviour, and it surprises me!
>
> I'll have to meditate about this.
>
> Best regards,
> Marcus
>
> On 22.05.2016 17:51, Marcus D. Leech via USRP-users wrote:
>> On 05/22/2016 11:46 AM, Marcus Müller via USRP-users wrote:
>>> Hm, interesting. I shouldn't have thought so, but: /something's/
>>> strange, and for some reason, perfectly valid uhd.tune_request
>>> objects evaluate to False in this case.
>>>
>>> So: since there's hardly any case that you can mis-construct a tune
>>> request (any frequency that is numerical should be fine, even
>>> negative numbers), I'd say: drop your "if not tx_center_freq" clause
>>> and just check whether the properties of the uhd.tune_result that
>>> tx.set_center_freq() return match your expectation.
>>>
>>> Best regards,
>>> Marcus
>> What are the boolean semantics of a structured data type like a
>> tune_request_t ? It's not immediately clear to me that there is a
>> mapping
>> in boolean for such structured data types.
>>
>>
>>>
>>> On 22.05.2016 17:32, Elvis Angelaccio via USRP-users wrote:
>>>> Hi, can someone explain me why `uhd.tune_request` always returns 0 in
>>>> the following Python code?
>>>> I'm running this on Linux with a USRP1 attached via USB.
>>>> The USRP has two 900 MHz daughterboards and two antennas attached to
>>>> TX/RX ports.
>>>>
>>>> Gnuradio version = 3.7.9.2
>>>> UHD version = 3.9.3
>>>>
>>>> ### CODE Snippet ####
>>>>
>>>> d = uhd.find_devices(uhd.device_addr(args.address_args))
>>>> if d:
>>>> print 'Available UHD devices: ' + str(d)
>>>>
>>>> try:
>>>> uhd_type = d[0].get('type')
>>>> except IndexError:
>>>> print 'Fatal error. Did you connect the USRP to an USB port?'
>>>> sys.exit(1)
>>>>
>>>> serial = d[0].get('serial')
>>>> tx = uhd.usrp_sink(
>>>> device_addr='serial=' + serial,
>>>> stream_args=uhd.stream_args(
>>>> 'fc32',
>>>> channels=range(1)
>>>> )
>>>> )
>>>>
>>>> tx_center_freq = uhd.tune_request(freq)
>>>>
>>>> if not tx_center_freq: # <===== Always happening.
>>>> print 'Could not set TX freq'
>>>> sys.exit(1)
>>>>
>>>> tx.set_center_freq(tx_center_freq)
>>>> ...
>>>>
>>>>
>>>> Best regards,
>>>> Elvis
>>>>
>>>> _______________________________________________
>>>> USRP-users mailing list
>>>> usrp-us...@lists.ettus.com
>>>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>>
>>>
>>>
>>> _______________________________________________
>>> USRP-users mailing list
>>> usrp-us...@lists.ettus.com
>>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>>
>>
>>
>> _______________________________________________
>> USRP-users mailing list
>> usrp-us...@lists.ettus.com
>> http://lists.ettus.com/mailman/listinfo/usrp-users_lists.ettus.com
>
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