4 files changed, 19 insertions, 2 deletions
diff --git a/host/lib/usrp/b100/b100_impl.cpp b/host/lib/usrp/b100/b100_impl.cpp
index 5e36a19dd..591a8b49f 100644
--- a/host/lib/usrp/b100/b100_impl.cpp
+++ b/host/lib/usrp/b100/b100_impl.cpp
@@ -275,8 +275,8 @@ b100_impl::b100_impl(const device_addr_t &device_addr){
     ////////////////////////////////////////////////////////////////////
     // and do the misc mboard sensors
     ////////////////////////////////////////////////////////////////////
-    //none for now...
-    _tree->create<int>(mb_path / "sensors"); //phony property so this dir exists
+    _tree->create<sensor_value_t>(mb_path / "sensors/ref_locked")
+        .publish(boost::bind(&b100_impl::get_ref_locked, this));
 
     ////////////////////////////////////////////////////////////////////
     // create frontend control objects
@@ -491,3 +491,8 @@ void b100_impl::enable_gpif(const bool en) {
 void b100_impl::clear_fpga_fifo(void) {
     _fx2_ctrl->usrp_control_write(VRQ_CLEAR_FPGA_FIFO, 0, 0, 0, 0);
 }
+
+sensor_value_t b100_impl::get_ref_locked(void){
+    const bool lock = _clock_ctrl->get_locked();
+    return sensor_value_t("Ref", lock, "locked", "unlocked");
+}
diff --git a/host/lib/usrp/b100/b100_impl.hpp b/host/lib/usrp/b100/b100_impl.hpp
index c9acb17d4..5ec3dde7b 100644
--- a/host/lib/usrp/b100/b100_impl.hpp
+++ b/host/lib/usrp/b100/b100_impl.hpp
@@ -34,6 +34,7 @@
 #include <uhd/utils/pimpl.hpp>
 #include <uhd/types/dict.hpp>
 #include <uhd/types/otw_type.hpp>
+#include <uhd/types/sensors.hpp>
 #include <uhd/types/clock_config.hpp>
 #include <uhd/types/stream_cmd.hpp>
 #include <uhd/usrp/mboard_eeprom.hpp>
@@ -129,6 +130,7 @@ private:
     void enable_gpif(const bool);
     void clear_fpga_fifo(void);
     void handle_async_message(uhd::transport::managed_recv_buffer::sptr);
+    uhd::sensor_value_t get_ref_locked(void);
 };
 
 #endif /* INCLUDED_b100_IMPL_HPP */
diff --git a/host/lib/usrp/b100/clock_ctrl.cpp b/host/lib/usrp/b100/clock_ctrl.cpp
index df1442420..fd398abff 100644
--- a/host/lib/usrp/b100/clock_ctrl.cpp
+++ b/host/lib/usrp/b100/clock_ctrl.cpp
@@ -428,6 +428,13 @@ public:
         this->latch_regs();
     }
 
+    bool get_locked(void){
+        static const boost::uint8_t addr = 0x01F;
+        boost::uint32_t reg = this->read_reg(addr);
+        _ad9522_regs.set_reg(addr, reg);
+        return _ad9522_regs.digital_lock_detect != 0;
+    }
+
 private:
     i2c_iface::sptr _iface;
     ad9522_regs_t _ad9522_regs;
diff --git a/host/lib/usrp/b100/clock_ctrl.hpp b/host/lib/usrp/b100/clock_ctrl.hpp
index 68c24bdce..387892bf7 100644
--- a/host/lib/usrp/b100/clock_ctrl.hpp
+++ b/host/lib/usrp/b100/clock_ctrl.hpp
@@ -125,6 +125,9 @@ public:
      */
     virtual void use_auto_ref(void) = 0;
 
+    //! Is the reference locked?
+    virtual bool get_locked(void) = 0;
+
 };
 
 #endif /* INCLUDED_B100_CLOCK_CTRL_HPP */