3 files changed, 23 insertions, 2 deletions
diff --git a/host/lib/usrp/b200/b200_cores.cpp b/host/lib/usrp/b200/b200_cores.cpp
index 3c55d3995..b076b9476 100644
--- a/host/lib/usrp/b200/b200_cores.cpp
+++ b/host/lib/usrp/b200/b200_cores.cpp
@@ -61,6 +61,14 @@ void b200_ref_pll_ctrl::set_lock_to_ext_ref(bool external)
     _spi->restore_perif();
 }
 
+bool b200_ref_pll_ctrl::set_refclk_frequency(int refclk_kHz)
+{
+    _spi->change_perif(b200_local_spi_core::PLL);
+    bool success = adf4001_ctrl::set_refclk_frequency(refclk_kHz);
+    _spi->restore_perif();
+    return success;
+}
+
 
 b200_local_spi_core::sptr b200_local_spi_core::make(
     uhd::wb_iface::sptr iface, b200_local_spi_core::perif_t default_perif)
diff --git a/host/lib/usrp/b200/b200_cores.hpp b/host/lib/usrp/b200/b200_cores.hpp
index 1042cf422..a29e18796 100644
--- a/host/lib/usrp/b200/b200_cores.hpp
+++ b/host/lib/usrp/b200/b200_cores.hpp
@@ -49,6 +49,7 @@ public:
 
     b200_ref_pll_ctrl(b200_local_spi_core::sptr spi);
     void set_lock_to_ext_ref(bool external) override;
+    virtual bool set_refclk_frequency(int refclk_kHz);
 
 private:
     b200_local_spi_core::sptr _spi;
diff --git a/host/lib/usrp/b200/b200_impl.cpp b/host/lib/usrp/b200/b200_impl.cpp
index 6de161e87..6b0960a62 100644
--- a/host/lib/usrp/b200/b200_impl.cpp
+++ b/host/lib/usrp/b200/b200_impl.cpp
@@ -518,8 +518,12 @@ b200_impl::b200_impl(
     ////////////////////////////////////////////////////////////////////
     // Create the GPSDO control
     ////////////////////////////////////////////////////////////////////
-    if (_gpsdo_capable) {
-        if ((_local_ctrl->peek32(RB32_CORE_STATUS) & 0xff) != B200_GPSDO_ST_NONE) {
+    if (_gpsdo_capable)
+    {
+
+        // Do not check this flag, I don't see why it is needed
+        //if ((_local_ctrl->peek32(RB32_CORE_STATUS) & 0xff) != B200_GPSDO_ST_NONE)
+        {
             UHD_LOGGER_INFO("B200") << "Detecting internal GPSDO.... " << std::flush;
             try {
                 _gps = gps_ctrl::make(_async_task_data->gpsdo_uart);
@@ -838,6 +842,14 @@ b200_impl::b200_impl(
     _tree->access<std::string>(mb_path / "clock_source/value").set("internal");
     _tree->access<std::string>(mb_path / "time_source/value").set("internal");
 
+    //GPS installed: use external ref, time, and init time spec
+    if (_gps and _gps->gps_detected()) {
+      const int freq = _gps->gps_refclock_frequency();
+      if (not _adf4001_iface->set_refclk_frequency(freq)) {
+        throw uhd::value_error("Could not set refclk frequency");
+      }
+    }
+
     // Set the DSP chains to some safe value
     for (size_t i = 0; i < _radio_perifs.size(); i++) {
         _radio_perifs[i].ddc->set_host_rate(