nes-proj/core/net/mac/tsch/tsch-adaptive-timesync.h
2015-12-07 11:51:41 +01:00

90 lines
3.5 KiB
C

/*
* Copyright (c) 2015, SICS Swedish ICT.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. Neither the name of the Institute nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE INSTITUTE AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE INSTITUTE OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* This file is part of the Contiki operating system.
*
*/
#ifndef __TSCH_ADAPTIVE_TIMESYNC_H__
#define __TSCH_ADAPTIVE_TIMESYNC_H__
/********** Includes **********/
#include "contiki.h"
#include "net/mac/tsch/tsch-private.h"
/******** Configuration *******/
/* Use SFD timestamp for synchronization? By default we merely rely on rtimer and busy wait
* until SFD is high, which we found to provide greater accuracy on JN516x and CC2420.
* Note: for association, however, we always use SFD timestamp to know the time of arrival
* of the EB (because we do not busy-wait for the whole scanning process)
* */
#ifdef TSCH_CONF_RESYNC_WITH_SFD_TIMESTAMPS
#define TSCH_RESYNC_WITH_SFD_TIMESTAMPS TSCH_CONF_RESYNC_WITH_SFD_TIMESTAMPS
#else
#define TSCH_RESYNC_WITH_SFD_TIMESTAMPS 0
#endif
/* If enabled, remove jitter due to measurement errors */
#ifdef TSCH_CONF_TIMESYNC_REMOVE_JITTER
#define TSCH_TIMESYNC_REMOVE_JITTER TSCH_CONF_TIMESYNC_REMOVE_JITTER
#else
#define TSCH_TIMESYNC_REMOVE_JITTER TSCH_RESYNC_WITH_SFD_TIMESTAMPS
#endif
/* The jitter to remove in ticks.
* This should be the sum of measurement errors on Tx and Rx nodes.
* */
#define TSCH_TIMESYNC_MEASUREMENT_ERROR US_TO_RTIMERTICKS(32)
/* Base drift value.
* Used to compensate locally know inaccuracies, such as
* the effect of having a binary 32.768 kHz timer as the TSCH time base. */
#ifdef TSCH_CONF_BASE_DRIFT_PPM
#define TSCH_BASE_DRIFT_PPM TSCH_CONF_BASE_DRIFT_PPM
#else
#define TSCH_BASE_DRIFT_PPM 0
#endif
/* The approximate number of slots per second */
#define TSCH_SLOTS_PER_SECOND (1000000 / TSCH_DEFAULT_TS_TIMESLOT_LENGTH)
/***** External Variables *****/
/* The neighbor last used as our time source */
extern struct tsch_neighbor *last_timesource_neighbor;
/********** Functions *********/
void tsch_timesync_update(struct tsch_neighbor *n, uint16_t time_delta_asn, int32_t drift_correction);
int32_t tsch_timesync_adaptive_compensate(rtimer_clock_t delta_ticks);
#endif /* __TSCH_ADAPTIVE_TIMESYNC_H__ */