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* Randomised backoff when broadcasting.

Browse source 
* Only warn about rxfifo overflows when sending.

* More intricate tests to verify if transmission really started.
This commit is contained in:
bg- 2007-04-04 11:46:10 +00:00
parent 9205ceda12
commit 478953dcf4
1 changed files with 17 additions and 9 deletions
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26
core/dev/cc2420.c
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@ -28,13 +28,14 @@
*
* This file is part of the Contiki operating system.
*
* @(#)$Id: cc2420.c,v 1.10 2007/02/01 14:00:27 bg- Exp $
* @(#)$Id: cc2420.c,v 1.11 2007/04/04 11:46:10 bg- Exp $
*/
/*
* This code is almost device independent and should be easy to port.
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "contiki.h"
@ -227,10 +228,12 @@ cc2420_send(struct hdr_802_15 *hdr, u8_t hdr_len,
if (hdr->dst == 0xffff) {
int i;
for (i = 1; i < 3; i++) {
for (i = 0; i < 3; i++) {
static unsigned delaymask[] = { 1024-1, 2048-1, 4096-1 };
if (cc2420_resend() >= 0)
return 0;
clock_delay(i*256);
PRINTF("resend i=%d\n", i);
clock_delay(rand() & delaymask[i]);
}
} else {
process_post(&cc2420_retransmit_process,
@ -254,7 +257,7 @@ cc2420_resend(void)
if (FIFOP_IS_1 && !FIFO_IS_1) {
/* RXFIFO overflow, send on retransmit. */
PRINTF("rxfifo overflow!\n");
return -4;
// return -4;
}
/* The TX FIFO can only hold one packet! Make sure to not overrun
@ -269,11 +272,16 @@ cc2420_resend(void)
#elif __AVR__
#define LOOP_20_SYMBOLS 500 /* XXX */
#endif
cc2420_strobe(CC2420_STXONCCA);
for (i = LOOP_20_SYMBOLS; i > 0; i--)
if (SFD_IS_1)
return 0; /* Transmission has started. */
if (CCA_IS_1) {
cc2420_strobe(CC2420_STXONCCA);
for (i = LOOP_20_SYMBOLS; i > 0; i--)
if (SFD_IS_1) {
if (cc2420_status() & BV(CC2420_TX_ACTIVE))
return 0; /* Transmission has started. */
else
break; /* We must be receiving. */
}
}
return -3; /* Transmission never started! */
}