diff options
Diffstat (limited to 'host/docs')
| -rw-r--r-- | host/docs/gpsdo_b2x0.dox | 7 | ||||
| -rw-r--r-- | host/docs/sync.dox | 10 | ||||
| -rw-r--r-- | host/docs/usrp_b200.dox | 3 |
3 files changed, 17 insertions, 3 deletions
diff --git a/host/docs/gpsdo_b2x0.dox b/host/docs/gpsdo_b2x0.dox index a54665427..97d97135a 100644 --- a/host/docs/gpsdo_b2x0.dox +++ b/host/docs/gpsdo_b2x0.dox @@ -69,5 +69,12 @@ using the **gps_gprmc**, and **gps_gpgga** sensors. Location information can be parsed out of the **gps_gpgga** sensor by using **gpsd** or another NMEA parser. +\section gpsdob_power Using a power supply with the B2x0 and GPSDO + +The GPSDOs for the B2x0 draw extra power, and when running off of bus power +only, brownouts are possible (although not guaranteed to happen). +It is recommended to use a wall power connector when using a B2x0 in +conjunction with a GPSDO. + */ // vim:ft=doxygen: diff --git a/host/docs/sync.dox b/host/docs/sync.dox index 8c609f407..15352c3a8 100644 --- a/host/docs/sync.dox +++ b/host/docs/sync.dox @@ -64,10 +64,10 @@ synchronize multiple pairs of devices. \section sync_time Synchronizing the Device Time The purpose of the PPS signal is to synchronously latch a time into the -device. You can use the uhd::multi_usrp::set_time_next_pps() function to either +device. You can use the uhd::usrp::multi_usrp::set_time_next_pps() function to either initialize the sample time to 0 or an absolute time, such as GPS time or UTC time. For the purposes of synchronizing devices, it doesn't matter -what time you initialize to when using uhd::multi_usrp::set_time_next_pps(). +what time you initialize to when using uhd::usrp::multi_usrp::set_time_next_pps(). \subsection sync_time_reg Method 1 - poll the USRP time registers @@ -80,6 +80,7 @@ determine that a PPS has occurred: while (last_pps_time == usrp->get_time_last_pps()){ //sleep 100 milliseconds (give or take) } + // This command will be processed fairly soon after the last PPS edge: usrp->set_time_next_pps(uhd::time_spec_t(0.0)); ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ @@ -97,9 +98,14 @@ PPS edge, and the user can also parse this string to determine GPS time: //call user's function to wait for NMEA message... //call user's function to parse the NMEA message... + gps_time = VALUE_IN_NMEA_MESSAGE; + // At the next PPS edge, set the device time to the GPS time: usrp->set_time_next_pps(uhd::time_spec_t(gps_time+1)); + // Now the device time should be in sync with the GPS time. ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ +Take a look at the `sync_to_gps` example for more detail. + \subsection sync_time_mimocable Method 3 - MIMO cable Note: This only applies to USRP2 and N200/N210. This method does *not* diff --git a/host/docs/usrp_b200.dox b/host/docs/usrp_b200.dox index c846e916f..2192ba63e 100644 --- a/host/docs/usrp_b200.dox +++ b/host/docs/usrp_b200.dox @@ -19,8 +19,9 @@ - Timed sampling in FPGA \section b200_power Power + In most cases, USB 3.0 bus power will be sufficient to power the device. -If using USB 2.0 or an internal GPSDO, an external power supply or a cable designed +If using USB 2.0 or a GPSDO, an external power supply or a cable designed to pull power from 2 USB ports (USB 3.0 dual A to micro-B or B) must be used. \section b200_imgs Specifying a Non-standard Image |