On 10/21/2012 07:40 PM, Nowlan, Sean wrote: > Hi all, > > Has anyone pushed timed commands to their limits? I have a few > questions: > > 1) How many commands fit in the queue?
16 because its implemented in an SRL16 fifo (it could be arbitrary, just an FPGA change away) > 2) How far in the future can you schedule a timed command? 10s which is just some arbitrary large timeout (any more and the host spits a command not ack'd error) > 3) Does the set_command_time() call (and subsequent command call) > block? Should these take roughly as much time as the RTT over > Ethernet to an N200? set_command_time() is actually devoid of any communication. Its just setting a property subsequent commands will only block (aka wait for an ack) if the command queue has become full, or a read operation is requested. > 4) I don't necessarily want to call timed commands from the top level > GNU Radio flowgraph. I want to delegate that to a custom GNU Radio > block. Can commands to the USRP be called from a GNU Radio block > other than uhd_usrp_source/sink? If so, what's the best way to > communicate between the threads? We have actually done this in pre-cog using the PMC RPC block from grextras. A block actually passes a message to the RPC block, which invokes a method on the usrp source/sink. This could be to set the command time. The code works, but might look a little funny. I am working (as we speak) on making it possible to deal with native python objects, rather than PMTs when working within python. > 5) If I can't do #4 due to GNU Radio's architecture, would it make > sense to use stream tags to associate a parameter change (like gain > or frequency) with a sample in the stream and implement the timed > command calls in gr_uhd_usrp_source/sink blocks acting when it sees > the tags? > An alternative to #4, would be to not RPC, but put a control message input into the UHD source/sink to also send commands. So, you can do #4 now. #5 is a future endeavor, but probably the right way to do it. -josh _______________________________________________ Discuss-gnuradio mailing list Discuss-gnuradio@gnu.org https://lists.gnu.org/mailman/listinfo/discuss-gnuradio
