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sync USRP time to GPS when GPSDO is used as clock source

This commit is contained in:
Andre Puschmann 2020-01-20 17:57:16 +01:00
parent c9ac42f11d
commit d62b835a4c
1 changed files with 73 additions and 2 deletions
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75
lib/src/phy/rf/rf_uhd_imp.c
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@ -23,6 +23,7 @@
#include <string.h>
#include <sys/time.h>
#include <uhd.h>
#include <uhd/types/sensors.h>
#include <unistd.h>
#include "rf_helper.h"
@ -160,7 +161,7 @@ void rf_uhd_register_error_handler(void* h, srslte_rf_error_handler_t new_handle
handler->uhd_error_handler = new_handler;
}
static bool find_string(uhd_string_vector_handle h, char* str)
static bool find_string(uhd_string_vector_handle h, const char* str)
{
char buff[128];
size_t n;
@ -174,6 +175,74 @@ static bool find_string(uhd_string_vector_handle h, char* str)
return false;
}
/**
* Set the USRP time to the current GPS time (if sensor is found)
*
* The GPS time is read and the USRP time is set to the next full second during the next PPS.
* It appears, however, that "uhd_usrp_set_time_next_pps()" which seems to be the correct function
* to use, doesn't work. The C API call "uhd_usrp_set_time_unknown_pps()" works well.
* @param handler Pointer to RF handler
* @return Any error returned by UHD
*/
static uhd_error set_time_to_gps_time(rf_uhd_handler_t* handler)
{
const char sensor_name[] = "gps_time";
uhd_string_vector_handle sensors;
uhd_string_vector_make(&sensors);
uhd_error error = uhd_usrp_get_mboard_sensor_names(handler->usrp, 0, &sensors);
#if PRINT_SENSOR_NAMES
size_t sensors_len;
uhd_string_vector_size(sensors, &sensors_len);
for (int i = 0; i < sensors_len; i++) {
char buff[256];
uhd_string_vector_at(sensors, i, buff, 128);
printf("sensor %s present\n", buff);
}
#endif
if (error == UHD_ERROR_NONE && find_string(sensors, sensor_name)) {
uhd_sensor_value_handle value_h;
uhd_sensor_value_make_from_string(&value_h, "w", "t", "f");
error = uhd_usrp_get_mboard_sensor(handler->usrp, sensor_name, 0, &value_h);
int full_secs = 0;
if (error == UHD_ERROR_NONE) {
uhd_sensor_value_data_type_t sensor_dtype;
uhd_sensor_value_data_type(value_h, &sensor_dtype);
full_secs = uhd_sensor_value_to_int(value_h, &full_secs);
// printf("GPS full_secs=%d\n", full_secs);
double frac_secs;
uhd_sensor_value_data_type(value_h, &sensor_dtype);
full_secs = uhd_sensor_value_to_realnum(value_h, &frac_secs);
// printf("GPS frac_secs=%f\n", frac_secs);
full_secs = frac_secs;
printf("Setting USRP time to %ds\n", full_secs);
error = uhd_usrp_set_time_unknown_pps(handler->usrp, full_secs + 1, 0.0);
if (error != UHD_ERROR_NONE) {
char err_msg[256];
uhd_usrp_last_error(handler->usrp, err_msg, 256);
fprintf(stderr, "Error code %d: %s\n", error, err_msg);
}
// sleep a second to make sure values are set correctly
sleep(1);
}
uhd_sensor_value_free(&value_h);
}
if (error != UHD_ERROR_NONE) {
fprintf(stderr, "USRP has no sensor \"%s\", or reading failed. UHD error: %i\n", sensor_name, error);
}
uhd_string_vector_free(&sensors);
return error;
}
// timeout in ms
static uhd_error
wait_sensor_locked(rf_uhd_handler_t* handler, char* sensor_name, bool is_mboard, int timeout, bool* is_locked)
@ -542,6 +611,7 @@ int rf_uhd_open_multi(char* args, void** h, uint32_t nof_channels)
} else if (clock_src == GPSDO) {
uhd_usrp_set_clock_source(handler->usrp, "gpsdo", 0);
uhd_usrp_set_time_source(handler->usrp, "gpsdo", 0);
set_time_to_gps_time(handler);
sensor_name = "gps_locked";
}
// wait until external reference / GPS is locked
@ -579,8 +649,9 @@ int rf_uhd_open_multi(char* args, void** h, uint32_t nof_channels)
uhd_usrp_set_tx_rate(handler->usrp, default_srate, i);
}
if (nof_channels > 1)
if (nof_channels > 1 && clock_src != GPSDO) {
uhd_usrp_set_time_unknown_pps(handler->usrp, 0, 0.0);
}
/* Initialize rx and tx stremers */
uhd_rx_streamer_make(&handler->rx_stream);