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Add optional correction for phase drift of receiver.

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This commit is contained in:
David Kopf 2011-12-01 10:02:37 -05:00
parent 81af871db9
commit 74aa63de43
2 changed files with 35 additions and 4 deletions
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29
core/net/mac/phase.c
View file

@ -28,7 +28,6 @@
*
* This file is part of the Contiki operating system.
*
* $Id: phase.c,v 1.17 2010/12/18 22:12:53 dak664 Exp $
*/
/**
@ -108,6 +107,9 @@ phase_update(const struct phase_list *list,
e = find_neighbor(list, neighbor);
if(e != NULL) {
if(mac_status == MAC_TX_OK) {
#if PHASE_DRIFT_CORRECT
e->drift = time-e->time;
#endif
e->time = time;
}
/* If the neighbor didn't reply to us, it may have switched
@ -140,6 +142,9 @@ phase_update(const struct phase_list *list,
}
rimeaddr_copy(&e->neighbor, neighbor);
e->time = time;
#if PHASE_DRIFT_CORRECT
e->drift = 0;
#endif
e->noacks = 0;
list_push(*list->list, e);
}
@ -197,8 +202,25 @@ phase_wait(struct phase_list *list,
now = RTIMER_NOW();
sync = (e == NULL) ? now : e->time;
wait = (rtimer_clock_t)((sync - now) &
(cycle_time - 1));
#if PHASE_DRIFT_CORRECT
{ int32_t s;
if (e->drift > cycle_time) {
s = e->drift%cycle_time/(e->drift/cycle_time); //drift per cycle
s = s*(now-sync)/cycle_time; //estimated drift to now
sync += s; //add it in
}
}
#endif
#if 1
/* Faster if cycle_time is a power of two */
wait = (rtimer_clock_t)((sync - now) & (cycle_time - 1));
#else
/* Works generally */
wait = cycle_time - (rtimer_clock_t)((now - sync) % cycle_time);
#endif
if(wait < guard_time) {
wait += cycle_time;
}
@ -226,6 +248,7 @@ phase_wait(struct phase_list *list,
expected = now + wait - guard_time;
if(!RTIMER_CLOCK_LT(expected, now)) {
/* Wait until the receiver is expected to be awake */
// printf("%d ",expected%cycle_time); //for spreadsheet export
while(RTIMER_CLOCK_LT(RTIMER_NOW(), expected));
}
return PHASE_SEND_NOW;

10
core/net/mac/phase.h
View file

@ -28,7 +28,6 @@
*
* This file is part of the Contiki operating system.
*
* $Id: phase.h,v 1.5 2010/09/13 13:39:05 adamdunkels Exp $
*/
/**
@ -48,10 +47,19 @@
#include "lib/memb.h"
#include "net/netstack.h"
#if PHASE_CONF_DRIFT_CORRECT
#define PHASE_DRIFT_CORRECT PHASE_CONF_DRIFT_CORRECT
#else
#define PHASE_DRIFT_CORRECT 1
#endif
struct phase {
struct phase *next;
rimeaddr_t neighbor;
rtimer_clock_t time;
#if PHASE_DRIFT_CORRECT
rtimer_clock_t drift;
#endif
uint8_t noacks;
struct timer noacks_timer;
};