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* If broadcast transmission never starts, retry with (nearly)

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exponential backoff.

* Fine-tune check for transmission start.
This commit is contained in:
bg- 2006-12-01 15:04:04 +00:00
parent 7b1dd9627a
commit 5d970109c8
1 changed files with 30 additions and 22 deletions
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52
core/dev/cc2420.c
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@ -28,7 +28,7 @@
*
* This file is part of the Contiki operating system.
*
* @(#)$Id: cc2420.c,v 1.6 2006/11/17 13:03:51 bg- Exp $
* @(#)$Id: cc2420.c,v 1.7 2006/12/01 15:04:04 bg- Exp $
*/
/*
* This code is almost device independent and should be possible to
@ -179,9 +179,7 @@ cc2420_send_data_ack(u16_t mac)
h.src = uip_hostaddr.u16[1];
h.dst = mac;
cc2420_send(&h, 10, NULL, 0);
return 0;
return cc2420_send(&h, 10, NULL, 0);
}
int
@ -224,40 +222,48 @@ cc2420_send(struct hdr_802_15 *hdr, u8_t hdr_len,
FASTSPI_WRITE_FIFO(payload, payload_len);
splx(s);
if (hdr->dst != 0xffff)
if (hdr->dst == 0xffff) {
int i;
for (i = 1; i < 3; i++) {
if (cc2420_resend() >= 0)
return 0;
clock_delay(i*256);
}
} else {
process_post(&cc2420_retransmit_process,
PROCESS_EVENT_MSG,
(void *)(unsigned)last_used_seq);
}
return cc2420_resend(); /* Send stuff from FIFO. */
}
/*
* Request packet to be sent using CSMA-CA. Requires that RSSI is
* valid.
*
* Return -3 on failure.
*/
int
cc2420_resend(void)
{
int i;
/* Request packet to be sent using CSMA-CA. */
cc2420_strobe(CC2420_STXONCCA);
/* The RX FIFO can only hold one packet! Make sure to not overrun
/* The TX FIFO can only hold one packet! Make sure to not overrun
* FIFO by waiting for transmission to start here and synchronizing
* with the CC2420_TX_ACTIVE check in cc2420_send.
*
* If RX FIFO is full or CSMA-CA never says ok we will have to
* terminate the loop below before SFD_IS_1!
* Note that we may have to wait up to 320 us (symbols) before
* transmission starts.
*/
for (i = 0; i < 1000; i++)
#ifdef TMOTE_SKY
#define LOOP_20_SYMBOLS 100 /* 326us (msp430 @ 2.4576MHz) */
#endif
cc2420_strobe(CC2420_STXONCCA);
for (i = 0; i < LOOP_20_SYMBOLS; i++)
if (SFD_IS_1)
return 0; /* Transmission has started. */
/*
* In the exceptional case that transmission never occurred we try
* again but never verify if the transmission ever starts. If a new
* call to cc2420_send() happens in a near future this transmission
* will be permanently canceled.
*/
cc2420_strobe(CC2420_STXONCCA);
return 0;
return -3; /* Transmission never started! */
}
void
@ -290,8 +296,10 @@ cc2420_on(void)
}
void
cc2420_set_chan_pan_addr(unsigned channel, unsigned pan,
unsigned addr, const u8_t *ieee_addr)
cc2420_set_chan_pan_addr(unsigned channel, /* 11 - 26 */
unsigned pan,
unsigned addr,
const u8_t *ieee_addr)
{
/*
* Subtract the base channel (11), multiply by 5, which is the