8 files changed, 81 insertions, 21 deletions
diff --git a/gr-uhd/doc/uhd.dox b/gr-uhd/doc/uhd.dox
index a3de8e3a24..69381610cd 100644
--- a/gr-uhd/doc/uhd.dox
+++ b/gr-uhd/doc/uhd.dox
@@ -93,6 +93,7 @@ Command name | Value Type   | Description
 `tune`       | tune_request | Like freq, but sets a full tune request (i.e. center frequency and DSP offset). Defaults to all channels.
 `lo_freq`    | double       | For fully manual tuning: Set the LO frequency (RF frequency). Conflicts with `freq`, `lo_offset`, and `tune`.
 `dsp_freq`   | double       | For fully manual tuning: Set the DSP frequency (CORDIC frequency). Conflicts with `freq`, `lo_offset`, and `tune`.
+`direction`  | string       | Used for timed transceiver tuning to ensure tuning order is maintained. Values other than 'TX' or 'RX' will be ignored.
 `rate`       | double       | See usrp_block::set_samp_rate(). *Always* affects all channels.
 `bandwidth`  | double       | See usrp_block::set_bandwidth(). Defaults to all channels.
 `time`       | timestamp    | Sets a command time. See usrp_block::set_command_time(). A value of PMT_NIL will clear the command time.
diff --git a/gr-uhd/include/gnuradio/uhd/usrp_source.h b/gr-uhd/include/gnuradio/uhd/usrp_source.h
index a0022b3876..027202e764 100644
--- a/gr-uhd/include/gnuradio/uhd/usrp_source.h
+++ b/gr-uhd/include/gnuradio/uhd/usrp_source.h
@@ -131,6 +131,33 @@ namespace gr {
        */
       virtual void issue_stream_cmd(const ::uhd::stream_cmd_t &cmd) = 0;
 
+      /*! Configure the timeout value on the UHD recv() call
+       *
+       * This is an advanced use parameter. Changing the timeout value affects
+       * the latency of this block; a high timeout value can be more optimal
+       * for high-throughput applications (e.g., 1 second) and setting it to
+       * zero will have the best latency. Changing the timeout value may also
+       * be useful for custom FPGA modifications, where traffic might not be
+       * continuously streaming.
+       * For specialized high-performance use cases, twiddling these knobs may
+       * improve performance, but changes are not generally applicable.
+       *
+       * Note that UHD's recv() call may block until the timeout is over, which
+       * means this block might also block for up to the timeout value.
+       *
+       * \param timeout Timeout parameter in seconds. Cf. the UHD manual for
+       *                uhd::rx_streamer::recv() for more details. A lower
+       *                value will mean lower latency, but higher CPU load.
+       * \param one_packet If true, only receive one packet at a time. Cf. the
+       *                   UHD manual for uhd::rx_streamer::recv() for more
+       *                   details. A value of true will mean lower latency,
+       *                   but higher CPU load.
+       */
+      virtual void set_recv_timeout(
+          const double timeout,
+          const bool one_packet=true
+      ) = 0;
+
       /*!
        * Returns identifying information about this USRP's configuration.
        * Returns motherboard ID, name, and serial.
diff --git a/gr-uhd/lib/usrp_block_impl.cc b/gr-uhd/lib/usrp_block_impl.cc
index 7f3478c1a5..803cfd71ec 100644
--- a/gr-uhd/lib/usrp_block_impl.cc
+++ b/gr-uhd/lib/usrp_block_impl.cc
@@ -39,6 +39,7 @@ const pmt::pmt_t CMD_BANDWIDTH_KEY = pmt::mp("bandwidth");
 const pmt::pmt_t CMD_TIME_KEY = pmt::mp("time");
 const pmt::pmt_t CMD_MBOARD_KEY = pmt::mp("mboard");
 const pmt::pmt_t CMD_ANTENNA_KEY = pmt::mp("antenna");
+const pmt::pmt_t CMD_DIRECTION_KEY = pmt::mp("direction");
 
 
 /**********************************************************************
@@ -209,11 +210,11 @@ bool usrp_block_impl::_check_mboard_sensors_locked()
 }
 
 void
-usrp_block_impl::_set_center_freq_from_internals_allchans()
+usrp_block_impl::_set_center_freq_from_internals_allchans(pmt::pmt_t direction)
 {
   while (_chans_to_tune.any()) {
     // This resets() bits, so this loop should not run indefinitely
-    _set_center_freq_from_internals(_chans_to_tune.find_first());
+    _set_center_freq_from_internals(_chans_to_tune.find_first(), direction);
   }
 }
 
@@ -539,8 +540,14 @@ void usrp_block_impl::msg_handler_command(pmt::pmt_t msg)
     }
   }
 
-  /// 4) Check if we need to re-tune
-  _set_center_freq_from_internals_allchans();
+  /// 4) See if a direction was specified
+  pmt::pmt_t direction = pmt::dict_ref(
+      msg, CMD_DIRECTION_KEY,
+      pmt::PMT_NIL // Anything except "TX" or "RX will default to the messaged block direction"
+  );
+
+  /// 5) Check if we need to re-tune
+  _set_center_freq_from_internals_allchans(direction);
 }
 
 
@@ -699,4 +706,3 @@ void usrp_block_impl::_cmd_handler_dspfreq(const pmt::pmt_t &dspfreq, int chan,
 
   _update_curr_tune_req(new_tune_request, chan);
 }
-
diff --git a/gr-uhd/lib/usrp_block_impl.h b/gr-uhd/lib/usrp_block_impl.h
index a1bbf97826..6b097505e1 100644
--- a/gr-uhd/lib/usrp_block_impl.h
+++ b/gr-uhd/lib/usrp_block_impl.h
@@ -29,13 +29,6 @@
 #include <boost/dynamic_bitset.hpp>
 #include <boost/bind.hpp>
 
-#define SET_CENTER_FREQ_FROM_INTERNALS(usrp_class, tune_method) \
-    ::uhd::tune_result_t \
-    usrp_class::_set_center_freq_from_internals(size_t chan) \
-    { \
-      _chans_to_tune.reset(chan); \
-      return _dev->tune_method(_curr_tune_req[chan], _stream_args.channels[chan]); \
-    }
 
 namespace gr {
   namespace uhd {
@@ -213,10 +206,10 @@ namespace gr {
       }
 
       //! Like set_center_freq(), but uses _curr_freq and _curr_lo_offset
-      virtual ::uhd::tune_result_t _set_center_freq_from_internals(size_t chan) = 0;
+      virtual ::uhd::tune_result_t _set_center_freq_from_internals(size_t chan, pmt::pmt_t direction) = 0;
 
       //! Calls _set_center_freq_from_internals() on all channels
-      void _set_center_freq_from_internals_allchans();
+      void _set_center_freq_from_internals_allchans(pmt::pmt_t direction);
 
       /**********************************************************************
        * Members
@@ -247,4 +240,3 @@ namespace gr {
 } /* namespace gr */
 
 #endif /* INCLUDED_GR_UHD_BLOCK_IMPL_H */
-
diff --git a/gr-uhd/lib/usrp_sink_impl.cc b/gr-uhd/lib/usrp_sink_impl.cc
index 2d347e3823..117b6e0a7d 100644
--- a/gr-uhd/lib/usrp_sink_impl.cc
+++ b/gr-uhd/lib/usrp_sink_impl.cc
@@ -135,7 +135,17 @@ namespace gr {
       return _dev->set_tx_freq(tune_request, chan);
     }
 
-    SET_CENTER_FREQ_FROM_INTERNALS(usrp_sink_impl, set_tx_freq);
+    ::uhd::tune_result_t
+    usrp_sink_impl::_set_center_freq_from_internals(size_t chan, pmt::pmt_t direction)
+    {
+      _chans_to_tune.reset(chan);
+      if (pmt::eqv(direction, pmt::mp("RX"))) {
+        // TODO: what happens if the RX device is not instantiated? Catch error?
+        return _dev->set_rx_freq(_curr_tune_req[chan], _stream_args.channels[chan]);
+      } else {
+        return _dev->set_tx_freq(_curr_tune_req[chan], _stream_args.channels[chan]);
+      }
+    }
 
     double
     usrp_sink_impl::get_center_freq(size_t chan)
diff --git a/gr-uhd/lib/usrp_sink_impl.h b/gr-uhd/lib/usrp_sink_impl.h
index d509baef90..f46d57cc0c 100644
--- a/gr-uhd/lib/usrp_sink_impl.h
+++ b/gr-uhd/lib/usrp_sink_impl.h
@@ -107,7 +107,7 @@ namespace gr {
 
     private:
       //! Like set_center_freq(), but uses _curr_freq and _curr_lo_offset
-      ::uhd::tune_result_t _set_center_freq_from_internals(size_t chan);
+      ::uhd::tune_result_t _set_center_freq_from_internals(size_t chan, pmt::pmt_t direction);
 
 #ifdef GR_UHD_USE_STREAM_API
       ::uhd::tx_streamer::sptr _tx_stream;
diff --git a/gr-uhd/lib/usrp_source_impl.cc b/gr-uhd/lib/usrp_source_impl.cc
index 23b94c684f..894a6d849b 100644
--- a/gr-uhd/lib/usrp_source_impl.cc
+++ b/gr-uhd/lib/usrp_source_impl.cc
@@ -71,6 +71,7 @@ namespace gr {
                     args_to_io_sig(stream_args)),
       usrp_block_impl(device_addr, stream_args, ""),
       _recv_timeout(0.1), // seconds
+      _recv_one_packet(true),
       _tag_now(false),
       _issue_stream_cmd_on_start(issue_stream_cmd_on_start)
     {
@@ -149,7 +150,17 @@ namespace gr {
       return res;
     }
 
-    SET_CENTER_FREQ_FROM_INTERNALS(usrp_source_impl, set_rx_freq);
+    ::uhd::tune_result_t
+    usrp_source_impl::_set_center_freq_from_internals(size_t chan, pmt::pmt_t direction)
+    {
+      _chans_to_tune.reset(chan);
+      if (pmt::eqv(direction, pmt::mp("TX"))) {
+        // TODO: what happens if the TX device is not instantiated? Catch error?
+        return _dev->set_tx_freq(_curr_tune_req[chan], _stream_args.channels[chan]);
+      } else {
+        return _dev->set_rx_freq(_curr_tune_req[chan], _stream_args.channels[chan]);
+      }
+    }
 
     double
     usrp_source_impl::get_center_freq(size_t chan)
@@ -489,6 +500,15 @@ namespace gr {
         _tag_now = true;
     }
 
+    void
+    usrp_source_impl::set_recv_timeout(
+            const double timeout,
+            const bool one_packet
+    ) {
+        _recv_timeout = timeout;
+        _recv_one_packet = one_packet;
+    }
+
     bool
     usrp_source_impl::start(void)
     {
@@ -534,7 +554,7 @@ namespace gr {
           _rx_stream->recv(outputs, nbytes/bpi, _metadata, 0.0);
         else
           // no rx streamer -- nothing to flush
-          break; 
+          break;
 #else
         _dev->get_device()->recv
           (outputs, nbytes/_type->size, _metadata, *_type,
@@ -625,7 +645,7 @@ namespace gr {
           noutput_items,
           _metadata,
           _recv_timeout,
-          true /* one packet -> minimize latency */
+          _recv_one_packet
       );
 #else
       size_t num_samps = _dev->get_device()->recv
diff --git a/gr-uhd/lib/usrp_source_impl.h b/gr-uhd/lib/usrp_source_impl.h
index 7ee5a138d4..d91fcec754 100644
--- a/gr-uhd/lib/usrp_source_impl.h
+++ b/gr-uhd/lib/usrp_source_impl.h
@@ -107,6 +107,7 @@ namespace gr {
       double set_lo_freq(double freq, const std::string &name, size_t chan);
 
       void issue_stream_cmd(const ::uhd::stream_cmd_t &cmd);
+      void set_recv_timeout(const double timeout, const bool one_packet);
       void flush(void);
       bool start(void);
       bool stop(void);
@@ -120,13 +121,16 @@ namespace gr {
 
     private:
       //! Like set_center_freq(), but uses _curr_freq and _curr_lo_offset
-      ::uhd::tune_result_t _set_center_freq_from_internals(size_t chan);
+      ::uhd::tune_result_t _set_center_freq_from_internals(size_t chan, pmt::pmt_t direction);
       void _cmd_handler_tag(const pmt::pmt_t &tag);
 
 #ifdef GR_UHD_USE_STREAM_API
       ::uhd::rx_streamer::sptr _rx_stream;
       size_t _samps_per_packet;
+      //! Timeout value for UHD's recv() call. Lower values mean lower latency.
       double _recv_timeout;
+      //! one_packet value for UHD's recv() call. 'true' is lower latency.
+      bool _recv_one_packet;
 #endif
       bool _tag_now;
       ::uhd::rx_metadata_t _metadata;