Error with ctrl+z

Hi,

I am implementing a stop-and-wait ARQ system using RFX2400 boards.
Sometimes
the transmitter suddenly stops working , and if I do ctrl+c the programs
stops but does not work wheras if I do ctrl +z, I recieve following
error
after sometime:

        ICE default IO error handler doing an exit(), pid = 3793, 

errno
= 0

And, if I try to run the program again, it stops communicating with USRP
with following error messages:

File “./mcl_snwARQ_tx.py”, line 118, in ?
main()
File “./mcl_snwARQ_tx.py”, line 100, in main
fg_rx = my_rx_graph(demods[options.modulation], rx_callback,
options)
File “./mcl_snwARQ_tx.py”, line 30, in init
self.rxpath = receive_path(self, demod_class, rx_callback, options)
File “/root/gnuradio-3.0.2/gr-mcl/receive_path.py”, line 59, in
init
self._setup_usrp_source()
File “/root/gnuradio-3.0.2/gr-mcl/receive_path.py”, line 119, in
_setup_usrp_source
fusb_nblocks=self._fusb_nblocks)
File “/usr/local/lib/python2.4/site-packages/gnuradio/usrp.py”, line
248,
in init
fpga_filename, firmware_filename)
File “/usr/local/lib/python2.4/site-packages/gnuradio/usrp1.py”, line
1229, in source_c
return _usrp1.source_c(*args)
RuntimeError: std::runtime_error

After that I need to unplug & plug the USB cable to start working with
it.
Ultimately I need to do ctrl+z and then unplug-plug the USB cable to
start
woking.

Can somebody help me out to resolve the problem which I am facing? I am
using following settings for transmitter side:
–tx-freq 2.4G --rx-freq 2.48G -r 500k -v -m gmsk --tx-amplitude 550
–rx-gain 60

and following settings for receiver side:
–rx-freq 2.40G --tx-freq 2.48G -r 500k -v -m gmsk --tx-amplitude 2000
–rx-gain 75

Thanks in advance.

Regards,
Tarun
University of Texas - Dallas

On Tue, Mar 13, 2007 at 03:53:31PM -0600, Tarun T. wrote:

And, if I try to run the program again, it stops communicating with USRP
with following error messages:

I suspect that you may have missed the very first line of the
debugging output which probably explains why it couldn’t open the
USRP. Did you capture both stdout and stderr?

Eric

Hi Eric
Thank you for your reply.

On 3/13/07, Eric B. [email protected] wrote:

I suspect that you may have missed the very first line of the
debugging output which probably explains why it couldn’t open the
USRP. Did you capture both stdout and stderr?

I didn’t capture the stdout and stderr, but checked with $ dmesg command
and
could not find anything which could catch my eyes.
I am little bit confused about the performance of my code. Sometimes it
works properly and sometimes not. Please find the entire code for the
Transmitter end:

from gnuradio import gr, gru, modulation_utils
from gnuradio import usrp
from gnuradio.eng_option import eng_option
from gnuradio import eng_notation, tx_debug_gui
from optparse import OptionParser
import random, time, struct, sys

from transmit_path import transmit_path
from receive_path import receive_path
import fusb_options

global tx_buffer, data_counter

class my_tx_graph(gr.flow_graph):
def init (self, modulator_class, options):
gr.flow_graph.init(self)
self.txpath = transmit_path(self, modulator_class, options)

class my_rx_graph(gr.flow_graph):
def init(self, demod_class, rx_callback, options):
gr.flow_graph.init(self)
self.rxpath = receive_path(self, demod_class, rx_callback,
options)

def main ():
global tx_buffer, data_counter
data_counter=50 #No of data packets to send

def send_pkt(payload='', eof=False):
    return fg_tx.txpath.send_pkt(payload, eof)

def rx_callback(ok, payload):
    global tx_buffer, data_counter
    (rx_data,) = struct.unpack('!H', payload[0:2])
    time.sleep(0.25)
    if rx_data == 255:
        print "Correctly Sent Data = '%d'" % (tx_buffer)
        data = random.randint(0,500)
        send_pkt(struct.pack('!H', data) + (pkt_size - 2) * chr(data 

&
0xff))
tx_buffer=data
data_counter-=1
else:
send_pkt(struct.pack(’!H’, tx_buffer) + (pkt_size - 2) *
chr(tx_buffer & 0xff))
print “Resend Data = ‘%d’” % (tx_buffer)
if data_counter == 0:
send_pkt(eof=True)
sys.exit(1)

mods = modulation_utils.type_1_mods()
demods = modulation_utils.type_1_demods()

parser = OptionParser (option_class=eng_option,

conflict_handler=“resolve”)
expert_grp = parser.add_option_group(“Expert”)

parser.add_option ("-m", "--modulation", type="choice", choices=

mods.keys(),
default=‘dbpsk’,
help=“Select modulation from: %s
[default=%%default]”
% (’, '.join(mods.keys()),))
parser.add_option ("-s", “–size”, type=“eng_float”, default=1500,
help=“set packet size [default=%default]”)
parser.add_option("-M", “–megabytes”, type=“eng_float”,
default=1.0,
help=“set megabytes to transmit
[default=%default]”)

receive_path.add_options(parser, expert_grp)

for mod in demods.values():
    mod.add_options(expert_grp)

transmit_path.add_options(parser, expert_grp)

for mod in mods.values():
    mod.add_options(expert_grp)


fusb_options.add_options(expert_grp)
(options, args) = parser.parse_args ()

if len(args) != 0:
    parser.print_help()
    raise SystemExit

if options.rx_freq is None:
    sys.stderr.write("usrp_siggen: must specify Rxeceiver RF center

frequency with -F \n")
parser.print_help()
raise SystemExit

if options.tx_freq is None:
    sys.stderr.write("usrp_siggen: must specify Transmitter RF 

center
frequency with -f \n")
parser.print_help()
raise SystemExit

# build the graph
fg_rx = my_rx_graph(demods[options.modulation], rx_callback, 

options)
fg_tx = my_tx_graph(mods[options.modulation], options)

r = gr.enable_realtime_scheduling()
if r != gr.RT_OK:
    print "Warning: Failed to enable realtime scheduling."
fg_rx.start()                       # start flow graph
fg_tx.start()                       # start flow graph

# Start the packet transmission
pkt_size = int(options.size)
tx_buffer=0
send_pkt(struct.pack('!H', tx_buffer) + (pkt_size - 2) * 

chr(tx_buffer &
0xff))

fg_tx.wait()                       # wait for it to finish
fg_tx.stop()
fg_rx.stop()

if name == ‘main’:
try:
main()
except KeyboardInterrupt:
pass

the reciever end has little bit of changes, but not much. For the time
being
I am transmitting 0xff for ACK and 0x00 for NAK in a packet rather than
single bit.

Can you please look at the code and guide me in right direction?

Eric

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