Merge branch 'maint'

14 files changed, 260 insertions, 212 deletions

diff --git a/host/lib/rfnoc/legacy_compat.cpp b/host/lib/rfnoc/legacy_compat.cpp
index dc711b909..70fe067f8 100644
--- a/host/lib/rfnoc/legacy_compat.cpp
+++ b/host/lib/rfnoc/legacy_compat.cpp
@@ -45,6 +45,7 @@ using uhd::stream_cmd_t;
  ***********************************************************************/
 static const std::string RADIO_BLOCK_NAME = "Radio";
 static const std::string DFIFO_BLOCK_NAME = "DmaFIFO";
+static const std::string SFIFO_BLOCK_NAME = "FIFO";
 static const std::string DDC_BLOCK_NAME = "DDC";
 static const std::string DUC_BLOCK_NAME = "DUC";
 static const size_t MAX_BYTES_PER_HEADER =
@@ -122,6 +123,7 @@ public:
         _has_ducs(not args.has_key("skip_duc") and not device->find_blocks(DUC_BLOCK_NAME).empty()),
         _has_ddcs(not args.has_key("skip_ddc") and not device->find_blocks(DDC_BLOCK_NAME).empty()),
         _has_dmafifo(not args.has_key("skip_dram") and not device->find_blocks(DFIFO_BLOCK_NAME).empty()),
+        _has_sramfifo(not args.has_key("skip_sram") and not device->find_blocks(SFIFO_BLOCK_NAME).empty()),
         _num_mboards(_tree->list("/mboards").size()),
         _num_radios_per_board(device->find_blocks<radio_ctrl>("0/Radio").size()), // These might throw, maybe we catch that and provide a nicer error message.
         _num_tx_chans_per_radio(
@@ -155,9 +157,13 @@ public:
             UHD_LOGGER_WARNING("RFNOC") << "[legacy_compat] No DUCs detected. You will only be able to transmit at the radio frontend rate." ;
         }
         if (args.has_key("skip_dram")) {
-            UHD_LEGACY_LOG() << "[legacy_compat] Skipping DRAM by user request." ;
-        } else if (not _has_dmafifo) {
-            UHD_LOGGER_WARNING("RFNOC") << "[legacy_compat] No DMA FIFO detected. You will only be able to transmit at slow rates." ;
+            UHD_LEGACY_LOG() << "[legacy_compat] Skipping DRAM by user request." << std::endl;
+        }
+        if (args.has_key("skip_sram")) {
+            UHD_LEGACY_LOG() << "[legacy_compat] Skipping SRAM by user request." << std::endl;
+        }
+        if (not _has_dmafifo and not _has_sramfifo) {
+            UHD_LOGGER_WARNING("RFNOC") << "[legacy_compat] No FIFO detected. Higher transmit rates may encounter errors.";
         }
 
         for (size_t mboard = 0; mboard < _num_mboards; mboard++) {
@@ -513,7 +519,9 @@ private: // methods
             size_t &port_index
     ) {
         if (dir == uhd::TX_DIRECTION) {
-            if (_has_dmafifo) {
+            if (_has_sramfifo) {
+                return block_id_t(mboard_idx, SFIFO_BLOCK_NAME, radio_index).to_string();
+            } else if (_has_dmafifo) {
                 port_index = radio_index;
                 return block_id_t(mboard_idx, DFIFO_BLOCK_NAME, 0).to_string();
             } else {
@@ -727,7 +735,15 @@ private: // methods
                             block_id_t(mboard, RADIO_BLOCK_NAME, radio), chan,
                             tx_bpp
                         );
-                        if (_has_dmafifo) {
+                        // Prioritize SRAM over DRAM for performance
+                        if (_has_sramfifo) {
+                            // We have SRAM FIFO *and* DUCs
+                            _graph->connect(
+                                block_id_t(mboard, SFIFO_BLOCK_NAME, radio), chan,
+                                block_id_t(mboard, DUC_BLOCK_NAME, radio), chan,
+                                tx_bpp
+                            );
+                        } else if (_has_dmafifo) {
                             // We have DMA FIFO *and* DUCs
                             _graph->connect(
                                 block_id_t(mboard, DFIFO_BLOCK_NAME, 0), radio,
@@ -735,6 +751,13 @@ private: // methods
                                 tx_bpp
                             );
                         }
+                    } else if (_has_sramfifo) {
+                            // We have SRAM FIFO, *no* DUCs
+                            _graph->connect(
+                                block_id_t(mboard, SFIFO_BLOCK_NAME, radio), radio,
+                                block_id_t(mboard, RADIO_BLOCK_NAME, radio), chan,
+                                tx_bpp
+                            );
                     } else if (_has_dmafifo) {
                             // We have DMA FIFO, *no* DUCs
                             _graph->connect(
@@ -834,6 +857,7 @@ private: // attributes
     const bool _has_ducs;
     const bool _has_ddcs;
     const bool _has_dmafifo;
+    const bool _has_sramfifo;
     const size_t _num_mboards;
     const size_t _num_radios_per_board;
     const size_t _num_tx_chans_per_radio;
diff --git a/host/lib/usrp/common/async_packet_handler.hpp b/host/lib/usrp/common/async_packet_handler.hpp
index fd4fed81e..01594be0b 100644
--- a/host/lib/usrp/common/async_packet_handler.hpp
+++ b/host/lib/usrp/common/async_packet_handler.hpp
@@ -40,7 +40,11 @@ namespace uhd{ namespace usrp{
         //load into metadata
         metadata.channel = channel;
         metadata.has_time_spec = if_packet_info.has_tsf;
-        metadata.time_spec = time_spec_t::from_ticks(if_packet_info.tsf, tick_rate);
+        if (tick_rate == 0.0) {
+            metadata.time_spec = 0.0;
+        } else {
+            metadata.time_spec = time_spec_t::from_ticks(if_packet_info.tsf, tick_rate);
+        }
         metadata.event_code = async_metadata_t::event_code_t(to_host(payload[0]) & 0xff);
 
         //load user payload
diff --git a/host/lib/usrp/dboard/db_twinrx.cpp b/host/lib/usrp/dboard/db_twinrx.cpp
index 91b38f90c..cedc26c36 100644
--- a/host/lib/usrp/dboard/db_twinrx.cpp
+++ b/host/lib/usrp/dboard/db_twinrx.cpp
@@ -112,7 +112,7 @@ public:
             "los/LO2/freq/value", prepend_ch("los/LO2/freq/desired", _ch_name), prepend_ch("los/LO2/freq/coerced", _ch_name),
             0.0, AUTO_RESOLVE_ON_READ_WRITE);
         get_rx_subtree()->create<std::vector<std::string> >("los/all/source/options")
-            .set(boost::assign::list_of("internal")("external")("companion")("disabled"));
+            .set(boost::assign::list_of("internal")("external")("companion")("disabled")("reimport"));
         expert_factory::add_prop_node<std::string>(_expert, get_rx_subtree(),
             "los/all/source/value", prepend_ch("los/all/source", _ch_name),
             "internal", AUTO_RESOLVE_ON_WRITE);
diff --git a/host/lib/usrp/dboard/db_xcvr2450.cpp b/host/lib/usrp/dboard/db_xcvr2450.cpp
index 62c5c39fb..fe6eca07b 100644
--- a/host/lib/usrp/dboard/db_xcvr2450.cpp
+++ b/host/lib/usrp/dboard/db_xcvr2450.cpp
@@ -371,7 +371,7 @@ double xcvr2450::set_lo_freq_core(double target_freq){
 
     //variables used in the calculation below
     double scaler = xcvr2450::is_highband(target_freq)? (4.0/5.0) : (4.0/3.0);
-    double ref_freq = this->get_iface()->get_clock_rate(dboard_iface::UNIT_TX);
+    double ref_freq = this->get_iface()->get_codec_rate(dboard_iface::UNIT_TX);
     int R, intdiv = 131, fracdiv = 0;
 
     //loop through values until we get a match
diff --git a/host/lib/usrp/dboard/twinrx/twinrx_ctrl.cpp b/host/lib/usrp/dboard/twinrx/twinrx_ctrl.cpp
index ddbbfaefb..00be82e1a 100644
--- a/host/lib/usrp/dboard/twinrx/twinrx_ctrl.cpp
+++ b/host/lib/usrp/dboard/twinrx/twinrx_ctrl.cpp
@@ -309,7 +309,7 @@ public:
         boost::lock_guard<boost::mutex> lock(_mutex);
         if (ch == CH1 or ch == BOTH) {
             _cpld_regs->rf1_reg5.set(rm::rf1_reg5_t::SW14_CTRL_CH2, bool2bin(source!=LO_COMPANION));
-            _cpld_regs->rf1_reg1.set(rm::rf1_reg1_t::SW15_CTRL_CH1, bool2bin(source==LO_EXTERNAL));
+            _cpld_regs->rf1_reg1.set(rm::rf1_reg1_t::SW15_CTRL_CH1, bool2bin(source==LO_EXTERNAL||source==LO_REIMPORT));
             _cpld_regs->rf1_reg1.set(rm::rf1_reg1_t::SW16_CTRL_CH1, bool2bin(source!=LO_INTERNAL));
             _lo1_src[size_t(CH1)] = source;
         }
@@ -332,7 +332,7 @@ public:
             _lo2_src[size_t(CH1)] = source;
         }
         if (ch == CH2 or ch == BOTH) {
-            _cpld_regs->if0_reg4.set(rm::if0_reg4_t::SW19_CTRL_CH1, bool2bin(source==LO_EXTERNAL));
+            _cpld_regs->if0_reg4.set(rm::if0_reg4_t::SW19_CTRL_CH1, bool2bin(source==LO_EXTERNAL||source==LO_REIMPORT));
             _cpld_regs->if0_reg0.set(rm::if0_reg0_t::SW20_CTRL_CH2, bool2bin(source==LO_INTERNAL||source==LO_DISABLED));
             _cpld_regs->if0_reg4.set(rm::if0_reg4_t::SW21_CTRL_CH2, bool2bin(source==LO_INTERNAL));
             _lo2_src[size_t(CH2)] = source;
diff --git a/host/lib/usrp/dboard/twinrx/twinrx_ctrl.hpp b/host/lib/usrp/dboard/twinrx/twinrx_ctrl.hpp
index 5537d00ab..2439addc4 100644
--- a/host/lib/usrp/dboard/twinrx/twinrx_ctrl.hpp
+++ b/host/lib/usrp/dboard/twinrx/twinrx_ctrl.hpp
@@ -35,7 +35,7 @@ public:
 
     virtual ~twinrx_ctrl() {}
 
-    enum channel_t { CH1 = 0, CH2 = 1, BOTH = 2};
+    enum channel_t { CH1 = 0, CH2 = 1, BOTH = 2 };
 
     enum preamp_state_t { PREAMP_LOWBAND, PREAMP_HIGHBAND, PREAMP_BYPASS };
 
@@ -43,7 +43,7 @@ public:
 
     enum preselector_path_t { PRESEL_PATH1, PRESEL_PATH2, PRESEL_PATH3, PRESEL_PATH4 };
 
-    enum lo_source_t { LO_INTERNAL, LO_EXTERNAL, LO_COMPANION, LO_DISABLED };
+    enum lo_source_t { LO_INTERNAL, LO_EXTERNAL, LO_COMPANION, LO_DISABLED, LO_REIMPORT };
 
     enum lo_export_source_t { LO_CH1_SYNTH, LO_CH2_SYNTH, LO_EXPORT_DISABLED };
 
diff --git a/host/lib/usrp/dboard/twinrx/twinrx_experts.cpp b/host/lib/usrp/dboard/twinrx/twinrx_experts.cpp
index 1a66e8fe7..c6a2d42c0 100644
--- a/host/lib/usrp/dboard/twinrx/twinrx_experts.cpp
+++ b/host/lib/usrp/dboard/twinrx/twinrx_experts.cpp
@@ -309,17 +309,18 @@ void twinrx_lo_config_expert::resolve()
         ("internal",  twinrx_ctrl::LO_INTERNAL)
         ("external",  twinrx_ctrl::LO_EXTERNAL)
         ("companion", twinrx_ctrl::LO_COMPANION)
-        ("disabled",  twinrx_ctrl::LO_DISABLED);
+        ("disabled",  twinrx_ctrl::LO_DISABLED)
+        ("reimport",  twinrx_ctrl::LO_REIMPORT);
 
     if (src_lookup.has_key(_lo_source_ch0)) {
         _lo1_src_ch0 = _lo2_src_ch0 = src_lookup[_lo_source_ch0];
     } else {
-        throw uhd::value_error("Invalid LO source for channel 0.Choose from {internal, external, companion}");
+        throw uhd::value_error("Invalid LO source for channel 0.Choose from {internal, external, companion, reimport}");
     }
     if (src_lookup.has_key(_lo_source_ch1)) {
         _lo1_src_ch1 = _lo2_src_ch1 = src_lookup[_lo_source_ch1];
     } else {
-        throw uhd::value_error("Invalid LO source for channel 1.Choose from {internal, external, companion}");
+        throw uhd::value_error("Invalid LO source for channel 1.Choose from {internal, external, companion, reimport}");
     }
 
     twinrx_ctrl::lo_export_source_t export_src = twinrx_ctrl::LO_EXPORT_DISABLED;
@@ -329,14 +330,16 @@ void twinrx_lo_config_expert::resolve()
     if (_lo_export_ch1 and (_lo_source_ch1 == "external")) {
         throw uhd::value_error("Cannot export an external LO for channel 1");
     }
+
+    // Determine which channel will provide the exported LO
     if (_lo_export_ch0 and _lo_export_ch1) {
         throw uhd::value_error("Cannot export LOs for both channels");
     } else if (_lo_export_ch0) {
-        export_src = (_lo1_src_ch0 == twinrx_ctrl::LO_INTERNAL) ?
-            twinrx_ctrl::LO_CH1_SYNTH : twinrx_ctrl::LO_CH2_SYNTH;
-    } else if (_lo_export_ch1) {
-        export_src = (_lo1_src_ch1 == twinrx_ctrl::LO_INTERNAL) ?
+        export_src = (_lo1_src_ch0 == twinrx_ctrl::LO_COMPANION) ?
             twinrx_ctrl::LO_CH2_SYNTH : twinrx_ctrl::LO_CH1_SYNTH;
+    } else if (_lo_export_ch1) {
+        export_src = (_lo1_src_ch1 == twinrx_ctrl::LO_COMPANION) ?
+            twinrx_ctrl::LO_CH1_SYNTH : twinrx_ctrl::LO_CH2_SYNTH;
     }
     _lo1_export_src = _lo2_export_src = export_src;
 }
@@ -351,14 +354,16 @@ void twinrx_lo_mapping_expert::resolve()
     static const size_t CH1_MSK = 0x2;
 
     // Determine which channels are "driving" each synthesizer
-    // First check for explicit requests i.e. lo_source "internal" or "companion"
+    // First check for explicit requests
+    // "internal" or "reimport" -> this channel
+    // "companion" -> other channel
     size_t synth_map[] = {0, 0};
-    if (_lox_src_ch0 == twinrx_ctrl::LO_INTERNAL) {
+    if (_lox_src_ch0 == twinrx_ctrl::LO_INTERNAL or _lox_src_ch0 == twinrx_ctrl::LO_REIMPORT) {
         synth_map[0] = synth_map[0] | CH0_MSK;
     } else if (_lox_src_ch0 == twinrx_ctrl::LO_COMPANION) {
         synth_map[1] = synth_map[1] | CH0_MSK;
     }
-    if (_lox_src_ch1 == twinrx_ctrl::LO_INTERNAL) {
+    if (_lox_src_ch1 == twinrx_ctrl::LO_INTERNAL or _lox_src_ch1 == twinrx_ctrl::LO_REIMPORT) {
         synth_map[1] = synth_map[1] | CH1_MSK;
     } else if (_lox_src_ch1 == twinrx_ctrl::LO_COMPANION) {
         synth_map[0] = synth_map[0] | CH1_MSK;
@@ -370,7 +375,7 @@ void twinrx_lo_mapping_expert::resolve()
     // to overlap tuning with signal dwell time.
     bool hopping_enabled = false;
     if (_lox_src_ch0 == twinrx_ctrl::LO_DISABLED) {
-        if (_lox_src_ch1 == twinrx_ctrl::LO_INTERNAL) {
+        if (_lox_src_ch1 == twinrx_ctrl::LO_INTERNAL or _lox_src_ch1 == twinrx_ctrl::LO_REIMPORT) {
             synth_map[0] = synth_map[0] | CH0_MSK;
             hopping_enabled = true;
         } else if (_lox_src_ch1 == twinrx_ctrl::LO_COMPANION) {
@@ -379,7 +384,7 @@ void twinrx_lo_mapping_expert::resolve()
         }
     }
     if (_lox_src_ch1 == twinrx_ctrl::LO_DISABLED) {
-        if (_lox_src_ch0 == twinrx_ctrl::LO_INTERNAL) {
+        if (_lox_src_ch0 == twinrx_ctrl::LO_INTERNAL or _lox_src_ch0 == twinrx_ctrl::LO_REIMPORT) {
             synth_map[1] = synth_map[1] | CH1_MSK;
             hopping_enabled = true;
         } else if (_lox_src_ch0 == twinrx_ctrl::LO_COMPANION) {
diff --git a/host/lib/usrp/device3/device3_impl.hpp b/host/lib/usrp/device3/device3_impl.hpp
index c2ec26f80..196d1fd4e 100644
--- a/host/lib/usrp/device3/device3_impl.hpp
+++ b/host/lib/usrp/device3/device3_impl.hpp
@@ -56,6 +56,7 @@ public:
     //! The purpose of a transport
     enum xport_type_t {
         CTRL = 0,
+        ASYNC_MSG,
         TX_DATA,
         RX_DATA
     };
diff --git a/host/lib/usrp/device3/device3_io_impl.cpp b/host/lib/usrp/device3/device3_io_impl.cpp
index 1668846c2..374232972 100644
--- a/host/lib/usrp/device3/device3_io_impl.cpp
+++ b/host/lib/usrp/device3/device3_io_impl.cpp
@@ -299,23 +299,17 @@ static void handle_rx_flowctrl(
 /***********************************************************************
  * TX Flow Control Functions
  **********************************************************************/
+#define DEVICE3_ASYNC_EVENT_CODE_FLOW_CTRL 0
+
 //! Stores the state of TX flow control
 struct tx_fc_cache_t
 {
-    tx_fc_cache_t(void):
-        stream_channel(0),
-        device_channel(0),
-        last_seq_out(0),
+    tx_fc_cache_t(size_t capacity):
         last_seq_ack(0),
-        last_seq_ack_cache(0) {}
+        space(capacity) {}
 
-    size_t stream_channel;
-    size_t device_channel;
-    size_t last_seq_out;
-    boost::atomic_size_t last_seq_ack;
-    size_t last_seq_ack_cache;
-    boost::shared_ptr<device3_impl::async_md_type> async_queue;
-    boost::shared_ptr<device3_impl::async_md_type> old_async_queue;
+    size_t last_seq_ack;
+    size_t space;
 };
 
 /*! Return the size of the flow control window in packets.
@@ -341,79 +335,77 @@ static size_t get_tx_flow_control_window(
     return window_in_pkts;
 }
 
-// TODO: Remove this function
-// This function only exists to make sure the transport is not destroyed
-// until it is no longer needed.
-static managed_send_buffer::sptr get_tx_buff(
-    zero_copy_if::sptr xport,
-    const double timeout
-){
-    return xport->get_send_buff(timeout);
-}
-
 static bool tx_flow_ctrl(
-    task::sptr /*holds ref*/,
     boost::shared_ptr<tx_fc_cache_t> fc_cache,
-    size_t fc_window,
+    zero_copy_if::sptr async_xport,
+    uint32_t (*endian_conv)(uint32_t),
+    void (*unpack)(const uint32_t *packet_buff, vrt::if_packet_info_t &),
     managed_buffer::sptr
 ) {
-    bool refresh_cache = false;
-
-    // Busy loop waiting for flow control update.  This is necessary because
-    // at this point there is data trying to be sent and it must be sent as
-    // quickly as possible when the flow control update arrives to avoid
-    // underruns at high rates.  This is also OK because it only occurs when
-    // data needs to be sent and flow control is holding it back.
     while (true)
     {
-        if (refresh_cache)
+        // If there is space
+        if (fc_cache->space)
         {
-            // update the cached value from the atomic
-            fc_cache->last_seq_ack_cache = fc_cache->last_seq_ack;
-        }
-
-        // delta is the amount of FC credit we've used up
-        const size_t delta = (fc_cache->last_seq_out & HW_SEQ_NUM_MASK) -
-            (fc_cache->last_seq_ack_cache & HW_SEQ_NUM_MASK);
-        // If we want to send another packet, we must have FC credit left
-        if ((delta & HW_SEQ_NUM_MASK) < fc_window)
-        {
-            // Packet will be sent
-            fc_cache->last_seq_out++; //update seq
+            // All is good - packet will be sent
+            fc_cache->space--;
             return true;
         }
-        else
+
+        // Look for a flow control message to update the space available in the buffer.
+        // A minimal timeout is used because larger timeouts can cause the thread to be
+        // scheduled out for too long at high data rates and result in underruns.
+        managed_recv_buffer::sptr buff = async_xport->get_recv_buff(0.000001);
+        if (buff)
         {
-            if (refresh_cache)
+            vrt::if_packet_info_t if_packet_info;
+            if_packet_info.num_packet_words32 = buff->size()/sizeof(uint32_t);
+            const uint32_t *packet_buff = buff->cast<const uint32_t *>();
+            try {
+                unpack(packet_buff, if_packet_info);
+            }
+            catch(const std::exception &ex)
             {
-                // We have already refreshed the cache and still
-                // lack flow control permission to send new data.
-
-                // A true busy loop choked out the message handler
-                // thread on machines with processor limitations
-                // (too few cores).  Yield to allow flow control
-                // receiver thread to operate.
-                boost::this_thread::yield();
+                UHD_LOG_ERROR("TX FLOW CTRL", "Error unpacking async flow control packet: " << ex.what());
+                continue;
             }
-            else
+
+            if (if_packet_info.packet_type != vrt::if_packet_info_t::PACKET_TYPE_FC)
             {
-                // Allow the cache to refresh and try again to
-                // see if the device has granted flow control permission.
-                refresh_cache = true;
+                UHD_LOG_ERROR(
+                    "TX FLOW CTRL",
+                    "Unexpected packet type received by flow control handler: " << if_packet_info.packet_type
+                );
+                continue;
             }
+
+            // update the amount of space
+            size_t seq_ack = endian_conv(packet_buff[if_packet_info.num_header_words32+1]);
+            fc_cache->space += (seq_ack - fc_cache->last_seq_ack) & HW_SEQ_NUM_MASK;
+            fc_cache->last_seq_ack = seq_ack;
         }
     }
     return false;
 }
 
-#define DEVICE3_ASYNC_EVENT_CODE_FLOW_CTRL 0
-/*! Handle incoming messages. If they're flow control, update the TX FC cache.
- * Otherwise, send them to the async message queue for the user to poll.
+/***********************************************************************
+ * TX Async Message Functions
+ **********************************************************************/
+struct async_tx_info_t
+{
+    size_t stream_channel;
+    size_t device_channel;
+    boost::shared_ptr<device3_impl::async_md_type> async_queue;
+    boost::shared_ptr<device3_impl::async_md_type> old_async_queue;
+};
+
+/*! Handle incoming messages.
+ *  Send them to the async message queue for the user to poll.
  *
  * This is run inside a uhd::task as long as this streamer lives.
  */
 static void handle_tx_async_msgs(
-        boost::shared_ptr<tx_fc_cache_t> fc_cache,
+        boost::shared_ptr<async_tx_info_t> async_info,
         zero_copy_if::sptr xport,
         endianness_t endianness,
         boost::function<double(void)> get_tick_rate
@@ -463,31 +455,24 @@ static void handle_tx_async_msgs(
             if_packet_info,
             packet_buff,
             tick_rate,
-            fc_cache->stream_channel
+            async_info->stream_channel
     );
 
-    // TODO: Shouldn't we be polling if_packet_info.packet_type == PACKET_TYPE_FC?
-    //       Thing is, on X300, packet_type == 0, so that wouldn't work. But it seems it should.
-    //The FC response and the burst ack are two indicators that the radio
-    //consumed packets. Use them to update the FC metadata
-    if (metadata.event_code == DEVICE3_ASYNC_EVENT_CODE_FLOW_CTRL) {
-        fc_cache->last_seq_ack = metadata.user_payload[0];
-    }
-
-    //FC responses don't propagate up to the user so filter them here
-    if (metadata.event_code != DEVICE3_ASYNC_EVENT_CODE_FLOW_CTRL) {
-        fc_cache->async_queue->push_with_pop_on_full(metadata);
-        metadata.channel = fc_cache->device_channel;
-        fc_cache->old_async_queue->push_with_pop_on_full(metadata);
+    // Filter out any flow control messages and cache the rest
+    if (metadata.event_code == DEVICE3_ASYNC_EVENT_CODE_FLOW_CTRL)
+    {
+        UHD_LOG_ERROR(
+            "TX ASYNC",
+            "Unexpected flow control message found in async message handling"
+        );
+    } else {
+        async_info->async_queue->push_with_pop_on_full(metadata);
+        metadata.channel = async_info->device_channel;
+        async_info->old_async_queue->push_with_pop_on_full(metadata);
         standard_async_msg_prints(metadata);
     }
 }
 
-
-
-/***********************************************************************
- * Async Data
- **********************************************************************/
 bool device3_impl::recv_async_msg(
     async_metadata_t &async_metadata, double timeout
 )
@@ -727,6 +712,20 @@ void device3_impl::update_tx_streamers(double /* rate */)
     }
 }
 
+// This class manages the lifetime of the TX async message handler task and transports
+class device3_send_packet_streamer : public sph::send_packet_streamer
+{
+public:
+	device3_send_packet_streamer(const size_t max_num_samps) : sph::send_packet_streamer(max_num_samps) {};
+	~device3_send_packet_streamer() {
+		_tx_async_msg_task.reset();	// Make sure the async task is destroyed before the transports
+	};
+
+	both_xports_t _xport;
+	both_xports_t _async_xport;
+	task::sptr _tx_async_msg_task;
+};
+
 tx_streamer::sptr device3_impl::get_tx_stream(const uhd::stream_args_t &args_)
 {
     boost::mutex::scoped_lock lock(_transport_setup_mutex);
@@ -742,7 +741,7 @@ tx_streamer::sptr device3_impl::get_tx_stream(const uhd::stream_args_t &args_)
     boost::shared_ptr<async_md_type> async_md(new async_md_type(1000/*messages deep*/));
 
     // II. Iterate over all channels
-    boost::shared_ptr<sph::send_packet_streamer> my_streamer;
+    boost::shared_ptr<device3_send_packet_streamer> my_streamer;
     // The terminator's lifetime is coupled to the streamer.
     // There is only one terminator. If the streamer has multiple channels,
     // it will be connected to each downstream block.
@@ -780,7 +779,8 @@ tx_streamer::sptr device3_impl::get_tx_stream(const uhd::stream_args_t &args_)
         uhd::sid_t stream_address = blk_ctrl->get_address(block_port);
         UHD_TX_STREAMER_LOG() << "creating tx stream " << tx_hints.to_string() ;
         both_xports_t xport = make_transport(stream_address, TX_DATA, tx_hints);
-        UHD_TX_STREAMER_LOG() << std::hex << "data_sid = " << xport.send_sid << std::dec ;
+        both_xports_t async_xport = make_transport(stream_address, ASYNC_MSG, device_addr_t(""));
+        UHD_TX_STREAMER_LOG() << std::hex << "[TX Streamer] data_sid = " << xport.send_sid << std::dec << std::endl;
 
         // To calculate the max number of samples per packet, we assume the maximum header length
         // to avoid fragmentation should the entire header be used.
@@ -791,8 +791,10 @@ tx_streamer::sptr device3_impl::get_tx_stream(const uhd::stream_args_t &args_)
 
         //make the new streamer given the samples per packet
         if (not my_streamer)
-            my_streamer = boost::make_shared<sph::send_packet_streamer>(spp);
+            my_streamer = boost::make_shared<device3_send_packet_streamer>(spp);
         my_streamer->resize(chan_list.size());
+        my_streamer->_xport = xport;
+        my_streamer->_async_xport = async_xport;
 
         //init some streamer stuff
         std::string conv_endianness;
@@ -828,29 +830,30 @@ tx_streamer::sptr device3_impl::get_tx_stream(const uhd::stream_args_t &args_)
                 block_port
         );
 
-        boost::shared_ptr<tx_fc_cache_t> fc_cache(new tx_fc_cache_t());
-        fc_cache->stream_channel = stream_i;
-        fc_cache->device_channel = mb_index;
-        fc_cache->async_queue = async_md;
-        fc_cache->old_async_queue = _async_md;
+        boost::shared_ptr<async_tx_info_t> async_tx_info(new async_tx_info_t());
+        async_tx_info->stream_channel = args.channels[stream_i];
+        async_tx_info->device_channel = mb_index;
+        async_tx_info->async_queue = async_md;
+        async_tx_info->old_async_queue = _async_md;
 
         boost::function<double(void)> tick_rate_retriever = boost::bind(
                 &rfnoc::tick_node_ctrl::get_tick_rate,
                 send_terminator,
                 std::set< rfnoc::node_ctrl_base::sptr >() // Need to specify default args with bind
         );
-        task::sptr task = task::make(
+
+        my_streamer->_tx_async_msg_task = task::make(
                 boost::bind(
                     &handle_tx_async_msgs,
-                    fc_cache,
-                    xport.recv,
+                    async_tx_info,
+                    my_streamer->_async_xport.recv,
                     xport.endianness,
                     tick_rate_retriever
                 )
         );
 
         blk_ctrl->sr_write(uhd::rfnoc::SR_CLEAR_RX_FC, 0xc1ea12, block_port);
-        blk_ctrl->sr_write(uhd::rfnoc::SR_RESP_IN_DST_SID, xport.recv_sid.get_dst(), block_port);
+        blk_ctrl->sr_write(uhd::rfnoc::SR_RESP_IN_DST_SID, my_streamer->_async_xport.recv_sid.get_dst(), block_port);
         UHD_TX_STREAMER_LOG() << "resp_in_dst_sid == " << boost::format("0x%04X") % xport.recv_sid.get_dst() ;
 
         // FIXME: Once there is a better way to map the radio block and port
@@ -865,7 +868,7 @@ tx_streamer::sptr device3_impl::get_tx_stream(const uhd::stream_args_t &args_)
             UHD_TX_STREAMER_LOG() << "Number of downstream radio nodes: " << downstream_radio_nodes.size();
             for(const boost::shared_ptr<uhd::rfnoc::radio_ctrl> &node:  downstream_radio_nodes) {
                 if (node->get_block_id() == radio_id) {
-                    node->sr_write(uhd::rfnoc::SR_RESP_IN_DST_SID, xport.send_sid.get_src(), radio_port);
+                    node->sr_write(uhd::rfnoc::SR_RESP_IN_DST_SID, my_streamer->_async_xport.recv_sid.get_dst(), radio_port);
                 }
             }
         } else {
@@ -878,24 +881,27 @@ tx_streamer::sptr device3_impl::get_tx_stream(const uhd::stream_args_t &args_)
             std::vector<boost::shared_ptr<uhd::rfnoc::radio_ctrl> > downstream_radio_nodes = blk_ctrl->find_downstream_node<uhd::rfnoc::radio_ctrl>();
             UHD_TX_STREAMER_LOG() << "Number of downstream radio nodes: " << downstream_radio_nodes.size();
             for(const boost::shared_ptr<uhd::rfnoc::radio_ctrl> &node:  downstream_radio_nodes) {
-                node->sr_write(uhd::rfnoc::SR_RESP_IN_DST_SID, xport.send_sid.get_src(), block_port);
+                node->sr_write(uhd::rfnoc::SR_RESP_IN_DST_SID, my_streamer->_async_xport.recv_sid.get_dst(), block_port);
             }
         }
 
         // Add flow control
-        xport.send = zero_copy_flow_ctrl::make(
-            xport.send,
-            boost::bind(&tx_flow_ctrl, task, fc_cache, fc_window, _1),
-            0
-        );
+        boost::shared_ptr<tx_fc_cache_t> fc_cache(new tx_fc_cache_t(fc_window));
+        my_streamer->_xport.send = zero_copy_flow_ctrl::make(
+            my_streamer->_xport.send,
+            boost::bind(
+                &tx_flow_ctrl,
+                fc_cache,
+                my_streamer->_xport.recv,
+                (xport.endianness == ENDIANNESS_BIG ? uhd::ntohx<uint32_t> : uhd::wtohx<uint32_t>),
+                (xport.endianness == ENDIANNESS_BIG ? vrt::chdr::if_hdr_unpack_be : vrt::chdr::if_hdr_unpack_le),
+                _1),
+            NULL);
 
         //Give the streamer a functor to get the send buffer
-        //get_tx_buff is static so bind has no lifetime issues
-        //xport.send (sptr) is required to add streamer->data-transport lifetime dependency
-        //task (sptr) is required to add  a streamer->async-handler lifetime dependency
         my_streamer->set_xport_chan_get_buff(
             stream_i,
-            boost::bind(&get_tx_buff, xport.send, _1)
+            boost::bind(&zero_copy_if::get_send_buff, my_streamer->_xport.send, _1)
         );
         //Give the streamer a functor handled received async messages
         my_streamer->set_async_receiver(
diff --git a/host/lib/usrp/e300/e300_fifo_config.cpp b/host/lib/usrp/e300/e300_fifo_config.cpp
index c4c563af6..89162a048 100644
--- a/host/lib/usrp/e300/e300_fifo_config.cpp
+++ b/host/lib/usrp/e300/e300_fifo_config.cpp
@@ -96,8 +96,8 @@ static UHD_INLINE size_t ZF_STREAM_OFF(const size_t which)
 struct e300_fifo_poll_waiter
 {
     e300_fifo_poll_waiter(const int fd):
-        fd(fd),
-       _poll_claimed(false)
+        _fd(fd),
+        _poll_claimed(false)
     {
         //NOP
     }
@@ -108,29 +108,36 @@ struct e300_fifo_poll_waiter
      */
     void wait(const double timeout)
     {
-        if (_poll_claimed.exchange(true))
+        if (timeout == 0) {
+            return;
+        }
+
+        boost::mutex::scoped_lock l(_mutex);
+        if (_poll_claimed)
         {
-            boost::mutex::scoped_lock l(mutex);
-            cond.wait(l);
+            _cond.timed_wait(l, boost::posix_time::microseconds(timeout*1000000));
         }
         else
         {
+            _poll_claimed = true;
+            l.unlock();
             struct pollfd fds[1];
-            fds[0].fd = fd;
+            fds[0].fd = _fd;
             fds[0].events = POLLIN;
             ::poll(fds, 1, long(timeout*1000));
             if (fds[0].revents & POLLIN)
-                ::read(fd, NULL, 0);
+                ::read(_fd, NULL, 0);
 
-            _poll_claimed = false;
-            cond.notify_all();
+            l.lock();
+            _poll_claimed = 0;
+            _cond.notify_all();
         }
     }
 
-    std::atomic_bool _poll_claimed;
-    boost::condition_variable cond;
-    boost::mutex mutex;
-    int fd;
+    boost::condition_variable _cond;
+    boost::mutex _mutex;
+    int _fd;
+    bool _poll_claimed;
 };
 
 static const size_t DEFAULT_FRAME_SIZE = 2048;
@@ -242,7 +249,7 @@ public:
     UHD_INLINE typename T::sptr get_buff(const double timeout)
     {
         const time_spec_t exit_time = time_spec_t::get_system_time() + time_spec_t(timeout);
-        do
+        while (1)
         {
             if (zf_peek32(_addrs.ctrl + ARBITER_RB_STATUS_OCC))
             {
@@ -254,10 +261,12 @@ public:
                     _index = 0;
                 return _buffs[_index++]->get_new<T>();
             }
+            if (time_spec_t::get_system_time() > exit_time) {
+                break;
+            }
             _waiter->wait(timeout);
             //boost::this_thread::sleep(boost::posix_time::milliseconds(1));
         }
-        while (time_spec_t::get_system_time() < exit_time);
 
         return typename T::sptr();
     }
diff --git a/host/lib/usrp/x300/x300_adc_dac_utils.cpp b/host/lib/usrp/x300/x300_adc_dac_utils.cpp
index fda0bb6c9..05228a309 100644
--- a/host/lib/usrp/x300/x300_adc_dac_utils.cpp
+++ b/host/lib/usrp/x300/x300_adc_dac_utils.cpp
@@ -21,53 +21,6 @@
 using namespace uhd::usrp::x300;
 
 /***********************************************************************
- * DAC: Reset and synchronization operations
- **********************************************************************/
-
-void x300_impl::synchronize_dacs(const std::vector<radio_perifs_t*>& radios)
-{
-    if (radios.size() < 2) return;  //Nothing to synchronize
-
-    //**PRECONDITION**
-    //This function assumes that all the VITA times in "radios" are synchronized
-    //to a common reference. Currently, this function is called in get_tx_stream
-    //which also has the same precondition.
-
-    //Reinitialize and resync all DACs
-    for (size_t i = 0; i < radios.size(); i++) {
-        radios[i]->dac->reset();
-    }
-
-    //Get a rough estimate of the cumulative command latency
-    boost::posix_time::ptime t_start = boost::posix_time::microsec_clock::local_time();
-    for (size_t i = 0; i < radios.size(); i++) {
-        radios[i]->ctrl->peek64(uhd::usrp::radio::RB64_TIME_NOW); //Discard value. We are just timing the call
-    }
-    boost::posix_time::time_duration t_elapsed =
-        boost::posix_time::microsec_clock::local_time() - t_start;
-
-    //Add 100% of headroom + uncertaintly to the command time
-    uint64_t t_sync_us = (t_elapsed.total_microseconds() * 2) + 13000 /*Scheduler latency*/;
-
-    //Pick radios[0] as the time reference.
-    uhd::time_spec_t sync_time =
-        radios[0]->time64->get_time_now() + uhd::time_spec_t(((double)t_sync_us)/1e6);
-
-    //Send the sync command
-    for (size_t i = 0; i < radios.size(); i++) {
-        radios[i]->ctrl->set_time(sync_time);
-        radios[i]->ctrl->poke32(uhd::usrp::radio::sr_addr(uhd::usrp::radio::DACSYNC), 0x1);    //Arm FRAMEP/N sync pulse
-        radios[i]->ctrl->set_time(uhd::time_spec_t(0.0));   //Clear command time
-    }
-
-    //Wait and check status
-    boost::this_thread::sleep(boost::posix_time::microseconds(t_sync_us));
-    for (size_t i = 0; i < radios.size(); i++) {
-        radios[i]->dac->verify_sync();
-    }
-}
-
-/***********************************************************************
  * ADC: Self-test operations
  **********************************************************************/
 
diff --git a/host/lib/usrp/x300/x300_impl.cpp b/host/lib/usrp/x300/x300_impl.cpp
index 08865f9a6..4601b2789 100644
--- a/host/lib/usrp/x300/x300_impl.cpp
+++ b/host/lib/usrp/x300/x300_impl.cpp
@@ -542,6 +542,8 @@ void x300_impl::setup_mb(const size_t mb_i, const uhd::device_addr_t &dev_addr)
     eth_addrs.push_back(eth0_addr);
 
     mb.next_src_addr = 0;   //Host source address for blocks
+    mb.next_tx_src_addr = 0;
+    mb.next_rx_src_addr = 0;
     if (dev_addr.has_key("second_addr")) {
         std::string eth1_addr = dev_addr["second_addr"];
 
@@ -1057,9 +1059,12 @@ x300_impl::~x300_impl(void)
 uint32_t x300_impl::mboard_members_t::allocate_pcie_dma_chan(const uhd::sid_t &tx_sid, const xport_type_t xport_type)
 {
     static const uint32_t CTRL_CHANNEL       = 0;
-    static const uint32_t FIRST_DATA_CHANNEL = 1;
+    static const uint32_t ASYNC_MSG_CHANNEL  = 1;
+    static const uint32_t FIRST_DATA_CHANNEL = 2;
     if (xport_type == CTRL) {
         return CTRL_CHANNEL;
+    } else if (xport_type == ASYNC_MSG) {
+        return ASYNC_MSG_CHANNEL;
     } else {
         // sid_t has no comparison defined, so we need to convert it uint32_t
         uint32_t raw_sid = tx_sid.get();
@@ -1081,6 +1086,24 @@ static uint32_t extract_sid_from_pkt(void* pkt, size_t) {
     return uhd::sid_t(uhd::wtohx(static_cast<const uint32_t*>(pkt)[1])).get_dst();
 }
 
+static uhd::transport::muxed_zero_copy_if::sptr make_muxed_pcie_msg_xport
+(
+    uhd::niusrprio::niusrprio_session::sptr rio_fpga_interface,
+    uint32_t dma_channel_num,
+    size_t max_muxed_ports
+) {
+    zero_copy_xport_params buff_args;
+    buff_args.send_frame_size = X300_PCIE_MSG_FRAME_SIZE;
+    buff_args.recv_frame_size = X300_PCIE_MSG_FRAME_SIZE;
+    buff_args.num_send_frames = X300_PCIE_MSG_NUM_FRAMES * max_muxed_ports;
+    buff_args.num_recv_frames = X300_PCIE_MSG_NUM_FRAMES * max_muxed_ports;
+
+    zero_copy_if::sptr base_xport = nirio_zero_copy::make(
+        rio_fpga_interface, dma_channel_num,
+        buff_args, uhd::device_addr_t());
+    return muxed_zero_copy_if::make(base_xport, extract_sid_from_pkt, max_muxed_ports);
+}
+
 uhd::both_xports_t x300_impl::make_transport(
     const uhd::sid_t &address,
     const xport_type_t xport_type,
@@ -1103,19 +1126,25 @@ uhd::both_xports_t x300_impl::make_transport(
             if (not mb.ctrl_dma_xport) {
                 //One underlying DMA channel will handle
                 //all control traffic
-                zero_copy_xport_params ctrl_buff_args;
-                ctrl_buff_args.send_frame_size = X300_PCIE_MSG_FRAME_SIZE;
-                ctrl_buff_args.recv_frame_size = X300_PCIE_MSG_FRAME_SIZE;
-                ctrl_buff_args.num_send_frames = X300_PCIE_MSG_NUM_FRAMES * X300_PCIE_MAX_MUXED_XPORTS;
-                ctrl_buff_args.num_recv_frames = X300_PCIE_MSG_NUM_FRAMES * X300_PCIE_MAX_MUXED_XPORTS;
-
-                zero_copy_if::sptr base_xport = nirio_zero_copy::make(
-                    mb.rio_fpga_interface, dma_channel_num,
-                    ctrl_buff_args, uhd::device_addr_t());
-                mb.ctrl_dma_xport = muxed_zero_copy_if::make(base_xport, extract_sid_from_pkt, X300_PCIE_MAX_MUXED_XPORTS);
+                mb.ctrl_dma_xport = make_muxed_pcie_msg_xport(
+                    mb.rio_fpga_interface,
+                    dma_channel_num,
+                    X300_PCIE_MAX_MUXED_CTRL_XPORTS);
             }
             //Create a virtual control transport
             xports.recv = mb.ctrl_dma_xport->make_stream(xports.recv_sid.get_dst());
+        } else if (xport_type == ASYNC_MSG) {
+            //Transport for async message stream
+            if (not mb.async_msg_dma_xport) {
+                //One underlying DMA channel will handle
+                //all async message traffic
+                mb.async_msg_dma_xport = make_muxed_pcie_msg_xport(
+                    mb.rio_fpga_interface,
+                    dma_channel_num,
+                    X300_PCIE_MAX_MUXED_ASYNC_XPORTS);
+            }
+            //Create a virtual async message transport
+            xports.recv = mb.async_msg_dma_xport->make_stream(xports.recv_sid.get_dst());
         } else {
             //Transport for data stream
             default_buff_args.send_frame_size =
@@ -1157,12 +1186,16 @@ uhd::both_xports_t x300_impl::make_transport(
 
     } else if (mb.xport_path == "eth") {
         // Decide on the IP/Interface pair based on the endpoint index
-        std::string interface_addr = mb.eth_conns[mb.next_src_addr].addr;
+        size_t &next_src_addr =
+            xport_type == TX_DATA ? mb.next_tx_src_addr :
+            xport_type == RX_DATA ? mb.next_rx_src_addr :
+            mb.next_src_addr;
+        std::string interface_addr = mb.eth_conns[next_src_addr].addr;
         const uint32_t xbar_src_addr =
-            mb.next_src_addr==0 ? X300_SRC_ADDR0 : X300_SRC_ADDR1;
+            next_src_addr==0 ? X300_SRC_ADDR0 : X300_SRC_ADDR1;
         const uint32_t xbar_src_dst =
-            mb.eth_conns[mb.next_src_addr].type==X300_IFACE_ETH0 ? X300_XB_DST_E0 : X300_XB_DST_E1;
-        mb.next_src_addr = (mb.next_src_addr + 1) % mb.eth_conns.size();
+            mb.eth_conns[next_src_addr].type==X300_IFACE_ETH0 ? X300_XB_DST_E0 : X300_XB_DST_E1;
+        next_src_addr = (next_src_addr + 1) % mb.eth_conns.size();
 
         xports.send_sid = this->allocate_sid(mb, address, xbar_src_addr, xbar_src_dst);
         xports.recv_sid = xports.send_sid.reversed();
diff --git a/host/lib/usrp/x300/x300_impl.hpp b/host/lib/usrp/x300/x300_impl.hpp
index 27f3f130e..7186e5f4f 100644
--- a/host/lib/usrp/x300/x300_impl.hpp
+++ b/host/lib/usrp/x300/x300_impl.hpp
@@ -63,7 +63,8 @@ static const size_t X300_PCIE_TX_DATA_NUM_FRAMES	    = 4096;
 static const size_t X300_PCIE_MSG_FRAME_SIZE            = 256;      //bytes
 static const size_t X300_PCIE_MSG_NUM_FRAMES            = 64;
 static const size_t X300_PCIE_MAX_CHANNELS              = 6;
-static const size_t X300_PCIE_MAX_MUXED_XPORTS          = 32;
+static const size_t X300_PCIE_MAX_MUXED_CTRL_XPORTS     = 32;
+static const size_t X300_PCIE_MAX_MUXED_ASYNC_XPORTS    = 4;
 
 static const size_t X300_10GE_DATA_FRAME_MAX_SIZE   = 8000;     // CHDR packet size in bytes
 static const size_t X300_1GE_DATA_FRAME_MAX_SIZE    = 1472;     // CHDR packet size in bytes
@@ -166,6 +167,8 @@ private:
 
         std::vector<x300_eth_conn_t> eth_conns;
         size_t next_src_addr;
+        size_t next_tx_src_addr;
+        size_t next_rx_src_addr;
 
         // Discover the ethernet connections per motherboard
         void discover_eth(const uhd::usrp::mboard_eeprom_t mb_eeprom,
@@ -207,6 +210,8 @@ private:
         std::map<uint32_t, uint32_t> _dma_chan_pool;
         //! Control transport for one PCIe connection
         uhd::transport::muxed_zero_copy_if::sptr ctrl_dma_xport;
+        //! Async message transport
+        uhd::transport::muxed_zero_copy_if::sptr async_msg_dma_xport;
 
         /*! Allocate or return a previously allocated PCIe channel pair
          *
diff --git a/host/lib/usrp/x300/x300_radio_ctrl_impl.cpp b/host/lib/usrp/x300/x300_radio_ctrl_impl.cpp
index daae309c3..1a37cbdd1 100644
--- a/host/lib/usrp/x300/x300_radio_ctrl_impl.cpp
+++ b/host/lib/usrp/x300/x300_radio_ctrl_impl.cpp
@@ -870,8 +870,14 @@ void x300_radio_ctrl_impl::synchronize_dacs(const std::vector<x300_radio_ctrl_im
     boost::posix_time::time_duration t_elapsed =
         boost::posix_time::microsec_clock::local_time() - t_start;
 
-    //Add 100% of headroom + uncertaintly to the command time
-    uint64_t t_sync_us = (t_elapsed.total_microseconds() * 2) + 13000 /*Scheduler latency*/;
+    //Set tick rate and make sure FRAMEP/N is 0
+    for (size_t i = 0; i < radios.size(); i++) {
+        radios[i]->set_command_tick_rate(radios[i]->_radio_clk_rate, IO_MASTER_RADIO);
+        radios[i]->_regs->misc_outs_reg.write(radio_regmap_t::misc_outs_reg_t::DAC_SYNC, 0);
+    }
+
+    //Add 100% of headroom + uncertainty to the command time
+    uint64_t t_sync_us = (t_elapsed.total_microseconds() * 2) + 16000 /*Scheduler latency*/;
 
     //Pick radios[0] as the time reference.
     uhd::time_spec_t sync_time =
@@ -879,15 +885,17 @@ void x300_radio_ctrl_impl::synchronize_dacs(const std::vector<x300_radio_ctrl_im
 
     //Send the sync command
     for (size_t i = 0; i < radios.size(); i++) {
-        radios[i]->set_command_tick_rate(radios[i]->_radio_clk_rate, IO_MASTER_RADIO);
-        radios[i]->_regs->misc_outs_reg.set(radio_regmap_t::misc_outs_reg_t::DAC_SYNC, 0);
         radios[i]->set_command_time(sync_time, IO_MASTER_RADIO);
         //Arm FRAMEP/N sync pulse by asserting a rising edge
-        radios[i]->_regs->misc_outs_reg.set(radio_regmap_t::misc_outs_reg_t::DAC_SYNC, 1);
-        radios[i]->_regs->misc_outs_reg.set(radio_regmap_t::misc_outs_reg_t::DAC_SYNC, 0);
+        radios[i]->_regs->misc_outs_reg.write(radio_regmap_t::misc_outs_reg_t::DAC_SYNC, 1);
         radios[i]->set_command_time(uhd::time_spec_t(0.0), IO_MASTER_RADIO);
     }
 
+    //Reset FRAMEP/N to 0
+    for (size_t i = 0; i < radios.size(); i++) {
+        radios[i]->_regs->misc_outs_reg.write(radio_regmap_t::misc_outs_reg_t::DAC_SYNC, 0);
+    }
+
     //Wait and check status
     boost::this_thread::sleep(boost::posix_time::microseconds(t_sync_us));
     for (size_t i = 0; i < radios.size(); i++) {