4 files changed, 19 insertions, 4 deletions
diff --git a/host/lib/usrp/common/ad9361_ctrl.cpp b/host/lib/usrp/common/ad9361_ctrl.cpp
index 2d9f297b3..54f0fcdbf 100644
--- a/host/lib/usrp/common/ad9361_ctrl.cpp
+++ b/host/lib/usrp/common/ad9361_ctrl.cpp
@@ -251,6 +251,11 @@ public:
         _device.set_filter(direction, chain, filter_name, filter);
     }
 
+    void output_digital_test_tone(bool enb)
+    {
+        _device.digital_test_tone(enb);
+    }
+
 private:
     static ad9361_device_t::direction_t _get_direction_from_antenna(const std::string& antenna)
     {
diff --git a/host/lib/usrp/common/ad9361_ctrl.hpp b/host/lib/usrp/common/ad9361_ctrl.hpp
index 044265422..5c438ee9c 100644
--- a/host/lib/usrp/common/ad9361_ctrl.hpp
+++ b/host/lib/usrp/common/ad9361_ctrl.hpp
@@ -154,6 +154,8 @@ public:
 
     //! Write back a filter
     virtual void set_filter(const std::string &which, const std::string &filter_name, const filter_info_base::sptr) = 0;
+
+    virtual void output_digital_test_tone(bool enb) = 0;
 };
 
 }}
diff --git a/host/lib/usrp/common/ad9361_driver/ad9361_device.cpp b/host/lib/usrp/common/ad9361_driver/ad9361_device.cpp
index c3bc2d32b..0a8a61575 100644
--- a/host/lib/usrp/common/ad9361_driver/ad9361_device.cpp
+++ b/host/lib/usrp/common/ad9361_driver/ad9361_device.cpp
@@ -1286,16 +1286,16 @@ double ad9361_device_t::_tune_helper(direction_t direction, const double value)
 
         /* Set band-specific settings. */
         if (value < _client_params->get_band_edge(AD9361_RX_BAND0)) {
-            _regs.inputsel = (_regs.inputsel & 0xC0) | 0x30;
+            _regs.inputsel = (_regs.inputsel & 0xC0) | 0x30; // Port C, balanced
         } else if ((value
                 >= _client_params->get_band_edge(AD9361_RX_BAND0))
                 && (value
                         < _client_params->get_band_edge(AD9361_RX_BAND1))) {
-            _regs.inputsel = (_regs.inputsel & 0xC0) | 0x0C;
+            _regs.inputsel = (_regs.inputsel & 0xC0) | 0x0C; // Port B, balanced
         } else if ((value
                 >= _client_params->get_band_edge(AD9361_RX_BAND1))
                 && (value <= 6e9)) {
-            _regs.inputsel = (_regs.inputsel & 0xC0) | 0x03;
+            _regs.inputsel = (_regs.inputsel & 0xC0) | 0x03; // Port A, balanced
         } else {
             throw uhd::runtime_error("[ad9361_device_t] [_tune_helper] INVALID_CODE_PATH");
         }
@@ -2127,7 +2127,7 @@ double ad9361_device_t::set_gain(direction_t direction, chain_t chain, const dou
     }
 }
 
-void ad9361_device_t::output_test_tone()
+void ad9361_device_t::output_test_tone()  // On RF side!
 {
     boost::lock_guard<boost::recursive_mutex> lock(_mutex);
     /* Output a 480 kHz tone at 800 MHz */
@@ -2137,6 +2137,12 @@ void ad9361_device_t::output_test_tone()
     _io_iface->poke8(0x3FE, 0x3F);
 }
 
+void ad9361_device_t::digital_test_tone(bool enb) // Digital output
+{
+    boost::lock_guard<boost::recursive_mutex> lock(_mutex);
+    _io_iface->poke8(0x3F4, 0x02 | (enb ? 0x01 : 0x00));
+}
+
 void ad9361_device_t::data_port_loopback(const bool loopback_enabled)
 {
     boost::lock_guard<boost::recursive_mutex> lock(_mutex);
diff --git a/host/lib/usrp/common/ad9361_driver/ad9361_device.h b/host/lib/usrp/common/ad9361_driver/ad9361_device.h
index efd0f017c..66bc2e8b9 100644
--- a/host/lib/usrp/common/ad9361_driver/ad9361_device.h
+++ b/host/lib/usrp/common/ad9361_driver/ad9361_device.h
@@ -115,6 +115,8 @@ public:
     /* Make AD9361 output its test tone. */
     void output_test_tone();
 
+    void digital_test_tone(bool enb); // Digital output
+
     /* Turn on/off AD9361's TX port --> RX port loopback. */
     void data_port_loopback(const bool loopback_enabled);