[Discuss-gnuradio] usrp & ppc-linux

[kilian]

Hi,

I received the usrp a short time ago and was so far able to at least
compile the basic toolset comming with the usrp-0.7 tarball. The host is
a dual address@hidden running yellowdog-linux-4.0 . I had no luck compiling
gnuradio for it though. This is acceptable, since I was just using the
Mac for convenience (I can switch to a PC). This article:

http://lists.gnu.org/archive/html/discuss-gnuradio/2003-12/msg00016.html

mentioned USB performance and now I would like to add another data point
to it. After I found out that I had to upload the firmware first, using
'burn-usrp2-eeprom', I ran test_usrp0 and got the following output:

# ./test_usrp0 -v
compute_freq_control_word: target = 0  actual = 0  delta = 0
compute_freq_control_word: target = 0  actual = 0  delta = 0
compute_freq_control_word: target = 0  actual = 0  delta = 0
compute_freq_control_word: target = 0  actual = 0  delta = 0
compute_freq_control_word: target = 0  actual = 0  delta = 0
xfered 5.37e+08 bytes in 21.8 seconds.  2.46e+07 bytes/sec.  cpu time =
1.16
0 underruns

# ./test_usrp0 -v -i
compute_freq_control_word: target = 0  actual = 0  delta = 0
compute_freq_control_word: target = 0  actual = 0  delta = 0
compute_freq_control_word: target = 0  actual = 0  delta = 0
compute_freq_control_word: target = 0  actual = 0  delta = 0
compute_freq_control_word: target = 0  actual = 0  delta = 0
rx_overrun
...
xfered 5.37e+08 bytes in 18.7 seconds.  2.867e+07 bytes/sec.  cpu time =
1.22
noverruns = 171

Well, this not too great, although better than the previous article
suggests some NEC chipsets are. I get no overruns on the PC. I'm a bit
puzzled about the fact that I get no underruns while transmitting (maybe
the test doesn't include that but the target should signal an underrun
somehow). 

In case you are wondering what kind of hardware I'm using, 'cat
/proc/bus/usb/devices'  shows in part:

...

T:  Bus=01 Lev=00 Prnt=00 Port=00 Cnt=00 Dev#=  1 Spd=480 MxCh= 5
B:  Alloc=  0/800 us ( 0%), #Int=  0, #Iso=  0
D:  Ver= 2.00 Cls=09(hub  ) Sub=00 Prot=01 MxPS= 8 #Cfgs=  1
P:  Vendor=0000 ProdID=0000 Rev= 2.06
S:  Manufacturer=Linux 2.6.8-1.ydl.7g5-smp ehci_hcd
S:  Product=NEC Corporation USB 2.0
S:  SerialNumber=0001:02:0b.2
C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=  0mA
I:  If#= 0 Alt= 0 #EPs= 1 Cls=09(hub  ) Sub=00 Prot=00 Driver=hub
E:  Ad=81(I) Atr=03(Int.) MxPS=   2 Ivl=256ms

T:  Bus=01 Lev=01 Prnt=01 Port=02 Cnt=01 Dev#= 12 Spd=480 MxCh= 0
D:  Ver= 2.00 Cls=ff(vend.) Sub=ff Prot=ff MxPS=64 #Cfgs=  1
P:  Vendor=fffe ProdID=0002 Rev= 1.02
S:  Manufacturer=Free Software Folks
S:  Product=USRP Rev 2
S:  SerialNumber=3.141593
C:* #Ifs= 3 Cfg#= 1 Atr=c0 MxPwr=  0mA
I:  If#= 0 Alt= 0 #EPs= 0 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
I:  If#= 1 Alt= 0 #EPs= 1 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
E:  Ad=02(O) Atr=02(Bulk) MxPS= 512 Ivl=0ms
I:  If#= 2 Alt= 0 #EPs= 1 Cls=ff(vend.) Sub=ff Prot=ff Driver=(none)
E:  Ad=86(I) Atr=02(Bulk) MxPS= 512 Ivl=0ms

I'm wondering whether this is a valid test for USB performance. If
anybody has found a good PCI based USB adapter please let me know.  

I mainly got the board for educational purposes and possibly to build a
receiver (to cover 1-30MHz as a first step). Now that the possibilities
(4RX/4TX channels) are starting to sink in, I'm getting all kinds of
ideas though (i.e. using the DACs for DDS, ...). 

I'm curious what the unpopulated J2001 can be used for. My assumption is
that the VCTCXO signal can be fed out for synchronization purposes. I
guess some small changes could also make that a clock input. I'm not
sure whether I ever want to do that, but this could be helpful in a
number of situations.  

I have yet to test the board with some actual input, but I'm pretty
happy with what I got so far. I've taken part in more difficult
projects, one annoying thing there being tightlipped hardware vendors.
The fact that one can easily get all the source code is awesome.

Thanks a lot,

Kilian