diff options
Diffstat (limited to 'lora_pkt_fwd/src/timersync.c')
| -rw-r--r-- | lora_pkt_fwd/src/timersync.c | 146 |
1 files changed, 146 insertions, 0 deletions
diff --git a/lora_pkt_fwd/src/timersync.c b/lora_pkt_fwd/src/timersync.c new file mode 100644 index 0000000..3dd919b --- /dev/null +++ b/lora_pkt_fwd/src/timersync.c @@ -0,0 +1,146 @@ +/* + / _____) _ | | +( (____ _____ ____ _| |_ _____ ____| |__ + \____ \| ___ | (_ _) ___ |/ ___) _ \ + _____) ) ____| | | || |_| ____( (___| | | | +(______/|_____)_|_|_| \__)_____)\____)_| |_| + (C)2013 Semtech-Cycleo + +Description: + LoRa concentrator : Timer synchronization + Provides synchronization between unix, concentrator and gps clocks + +License: Revised BSD License, see LICENSE.TXT file include in the project +Maintainer: Michael Coracin +*/ + +/* -------------------------------------------------------------------------- */ +/* --- DEPENDANCIES --------------------------------------------------------- */ + +#include <stdio.h> /* printf, fprintf, snprintf, fopen, fputs */ +#include <stdint.h> /* C99 types */ +#include <pthread.h> + +#include "trace.h" +#include "timersync.h" +#include "loragw_hal.h" +#include "loragw_reg.h" +#include "loragw_aux.h" + +/* -------------------------------------------------------------------------- */ +/* --- PRIVATE CONSTANTS & TYPES -------------------------------------------- */ + +/* -------------------------------------------------------------------------- */ +/* --- PRIVATE MACROS ------------------------------------------------------- */ + +#define timersub(a, b, result) \ + do { \ + (result)->tv_sec = (a)->tv_sec - (b)->tv_sec; \ + (result)->tv_usec = (a)->tv_usec - (b)->tv_usec; \ + if ((result)->tv_usec < 0) { \ + --(result)->tv_sec; \ + (result)->tv_usec += 1000000; \ + } \ + } while (0) + +/* -------------------------------------------------------------------------- */ +/* --- PRIVATE VARIABLES (GLOBAL) ------------------------------------------- */ + +static pthread_mutex_t mx_timersync = PTHREAD_MUTEX_INITIALIZER; /* control access to timer sync offsets */ +static struct timeval offset_unix_concent = {0,0}; /* timer offset between unix host and concentrator */ + +/* -------------------------------------------------------------------------- */ +/* --- PRIVATE SHARED VARIABLES (GLOBAL) ------------------------------------ */ +extern bool exit_sig; +extern bool quit_sig; +extern pthread_mutex_t mx_concent; + +/* -------------------------------------------------------------------------- */ +/* --- PUBLIC FUNCTIONS DEFINITION ------------------------------------------ */ + +int get_concentrator_time(struct timeval *concent_time, struct timeval unix_time) { + struct timeval local_timeval; + + if (concent_time == NULL) { + MSG("ERROR: %s invalid parameter\n", __FUNCTION__); + return -1; + } + + pthread_mutex_lock(&mx_timersync); /* protect global variable access */ + timersub(&unix_time, &offset_unix_concent, &local_timeval); + pthread_mutex_unlock(&mx_timersync); + + /* TODO: handle sx1301 coutner wrap-up !! */ + concent_time->tv_sec = local_timeval.tv_sec; + concent_time->tv_usec = local_timeval.tv_usec; + + MSG_DEBUG(DEBUG_TIMERSYNC, " --> TIME: unix current time is %ld,%ld\n", unix_time.tv_sec, unix_time.tv_usec); + MSG_DEBUG(DEBUG_TIMERSYNC, " offset is %ld,%ld\n", offset_unix_concent.tv_sec, offset_unix_concent.tv_usec); + MSG_DEBUG(DEBUG_TIMERSYNC, " sx1301 current time is %ld,%ld\n", local_timeval.tv_sec, local_timeval.tv_usec); + + return 0; +} + +/* ---------------------------------------------------------------------------------------------- */ +/* --- THREAD 6: REGULARLAY MONITOR THE OFFSET BETWEEN UNIX CLOCK AND CONCENTRATOR CLOCK -------- */ + +void thread_timersync(void) { + struct timeval unix_timeval; + struct timeval concentrator_timeval; + uint32_t sx1301_timecount = 0; + struct timeval offset_previous = {0,0}; + struct timeval offset_drift = {0,0}; /* delta between current and previous offset */ + + while (!exit_sig && !quit_sig) { + /* Regularly disable GPS mode of concentrator's counter, in order to get + real timer value for synchronizing with host's unix timer */ + MSG("\nINFO: Disabling GPS mode for concentrator's counter...\n"); + pthread_mutex_lock(&mx_concent); + lgw_reg_w(LGW_GPS_EN, 0); + pthread_mutex_unlock(&mx_concent); + + /* Get current unix time */ + gettimeofday(&unix_timeval, NULL); + + /* Get current concentrator counter value (1MHz) */ + pthread_mutex_lock(&mx_concent); + lgw_get_trigcnt(&sx1301_timecount); + pthread_mutex_unlock(&mx_concent); + concentrator_timeval.tv_sec = sx1301_timecount / 1000000UL; + concentrator_timeval.tv_usec = sx1301_timecount - (concentrator_timeval.tv_sec * 1000000UL); + + /* Compute offset between unix and concentrator timers, with microsecond precision */ + offset_previous.tv_sec = offset_unix_concent.tv_sec; + offset_previous.tv_usec = offset_unix_concent.tv_usec; + + /* TODO: handle sx1301 coutner wrap-up */ + pthread_mutex_lock(&mx_timersync); /* protect global variable access */ + timersub(&unix_timeval, &concentrator_timeval, &offset_unix_concent); + pthread_mutex_unlock(&mx_timersync); + + timersub(&offset_unix_concent, &offset_previous, &offset_drift); + + MSG_DEBUG(DEBUG_TIMERSYNC, " sx1301 = %u (µs) - timeval (%ld,%ld)\n", + sx1301_timecount, + concentrator_timeval.tv_sec, + concentrator_timeval.tv_usec); + MSG_DEBUG(DEBUG_TIMERSYNC, " unix_timeval = %ld,%ld\n", unix_timeval.tv_sec, unix_timeval.tv_usec); + + MSG("INFO: host/sx1301 time offset=(%lds:%ldµs) - drift=%ldµs\n", + offset_unix_concent.tv_sec, + offset_unix_concent.tv_usec, + offset_drift.tv_sec * 1000000UL + offset_drift.tv_usec); + MSG("INFO: Enabling GPS mode for concentrator's counter.\n\n"); + pthread_mutex_lock(&mx_concent); /* TODO: Is it necessary to protect here? */ + lgw_reg_w(LGW_GPS_EN, 1); + pthread_mutex_unlock(&mx_concent); + + /* delay next sync */ + /* If we consider a crystal oscillator precision of about 20ppm worst case, and a clock + running at 1MHz, this would mean 1µs drift every 50000µs (10000000/20). + As here the time precision is not critical, we should be able to cope with at least 1ms drift, + which should occur after 50s (50000µs * 1000). + Let's set the thread sleep to 1 minute for now */ + wait_ms(60000); + } +} |