usrp2: turn on ups_per_sec to avoid timeout issues on low sample rates

3 files changed, 2 insertions, 5 deletions

diff --git a/host/docs/transport.rst b/host/docs/transport.rst
index 2371d2497..e7c2f1885 100644
--- a/host/docs/transport.rst
+++ b/host/docs/transport.rst
@@ -47,7 +47,7 @@ which allows the host to determine throttling conditions for the transmission of
 The following mechanisms affect the transmission of periodic update packets:
 
 * **ups_per_fifo:** The number of update packets for each FIFO's worth of bytes sent into the device
-* **ups_per_sec:** The number of update packets per second (disabled by default)
+* **ups_per_sec:** The number of update packets per second (defaults to 20 updates per second)
 
 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
 Resize socket buffers
diff --git a/host/examples/tx_timed_samples.cpp b/host/examples/tx_timed_samples.cpp
index 03f87122d..d33dc13c3 100644
--- a/host/examples/tx_timed_samples.cpp
+++ b/host/examples/tx_timed_samples.cpp
@@ -100,9 +100,6 @@ int UHD_SAFE_MAIN(int argc, char *argv[]){
             uhd::device::SEND_MODE_ONE_PACKET, timeout
         );
 
-        //use a small timeout for subsequent packets
-        timeout = 0.1;
-
         //do not use time spec for subsequent packets
         md.has_time_spec = false;
 
diff --git a/host/lib/usrp/usrp2/mboard_impl.cpp b/host/lib/usrp/usrp2/mboard_impl.cpp
index 2885e57e4..027cb5f78 100644
--- a/host/lib/usrp/usrp2/mboard_impl.cpp
+++ b/host/lib/usrp/usrp2/mboard_impl.cpp
@@ -116,7 +116,7 @@ usrp2_mboard_impl::usrp2_mboard_impl(
     dsp_init();
 
     //setting the cycles per update (disabled by default)
-    const double ups_per_sec = device_addr.cast<double>("ups_per_sec", 0.0);
+    const double ups_per_sec = device_addr.cast<double>("ups_per_sec", 20);
     if (ups_per_sec > 0.0){
         const size_t cycles_per_up = size_t(_clock_ctrl->get_master_clock_rate()/ups_per_sec);
         _iface->poke32(U2_REG_TX_CTRL_CYCLES_PER_UP, U2_FLAG_TX_CTRL_UP_ENB | cycles_per_up);