3 files changed, 27 insertions, 1 deletions
diff --git a/host/docs/usrp_e1x0.rst b/host/docs/usrp_e1x0.rst
index 9373e5255..189cbb86b 100644
--- a/host/docs/usrp_e1x0.rst
+++ b/host/docs/usrp_e1x0.rst
@@ -130,7 +130,7 @@ The LEDs on the front panel can be useful in debugging hardware and software
 issues.  The LEDs reveal the following about the state of the device:
 
 * **LED A:** transmitting
-* **LED B:** fpga loaded
+* **LED B:** PPS signal
 * **LED C:** receiving
 * **LED D:** fpga loaded
 * **LED E:** reference lock
diff --git a/host/lib/usrp/b100/b100_impl.cpp b/host/lib/usrp/b100/b100_impl.cpp
index 94dc88db4..b226e113a 100644
--- a/host/lib/usrp/b100/b100_impl.cpp
+++ b/host/lib/usrp/b100/b100_impl.cpp
@@ -554,6 +554,19 @@ void b100_impl::set_db_eeprom(const std::string &type, const uhd::usrp::dboard_e
 }
 
 void b100_impl::update_clock_source(const std::string &source){
+
+    if (source == "pps_sync"){
+        _clock_ctrl->use_external_ref();
+        _fifo_ctrl->poke32(TOREG(SR_MISC+2), 1);
+        return;
+    }
+    if (source == "_pps_sync_"){
+        _clock_ctrl->use_external_ref();
+        _fifo_ctrl->poke32(TOREG(SR_MISC+2), 3);
+        return;
+    }
+    _fifo_ctrl->poke32(TOREG(SR_MISC+2), 0);
+
     if      (source == "auto")     _clock_ctrl->use_auto_ref();
     else if (source == "internal") _clock_ctrl->use_internal_ref();
     else if (source == "external") _clock_ctrl->use_external_ref();
diff --git a/host/lib/usrp/e100/e100_impl.cpp b/host/lib/usrp/e100/e100_impl.cpp
index a517dfcba..ef0351bd2 100644
--- a/host/lib/usrp/e100/e100_impl.cpp
+++ b/host/lib/usrp/e100/e100_impl.cpp
@@ -486,6 +486,19 @@ void e100_impl::set_db_eeprom(const std::string &type, const uhd::usrp::dboard_e
 }
 
 void e100_impl::update_clock_source(const std::string &source){
+
+    if (source == "pps_sync"){
+        _clock_ctrl->use_external_ref();
+        _fifo_ctrl->poke32(TOREG(SR_MISC+2), 1);
+        return;
+    }
+    if (source == "_pps_sync_"){
+        _clock_ctrl->use_external_ref();
+        _fifo_ctrl->poke32(TOREG(SR_MISC+2), 3);
+        return;
+    }
+    _fifo_ctrl->poke32(TOREG(SR_MISC+2), 0);
+
     if      (source == "auto")     _clock_ctrl->use_auto_ref();
     else if (source == "internal") _clock_ctrl->use_internal_ref();
     else if (source == "external") _clock_ctrl->use_external_ref();