From f0891be21833833bc48e3aca7bfb9e4fce67fc96 Mon Sep 17 00:00:00 2001
From: nvt-se <nvt-se>
Date: Thu, 20 Dec 2007 14:44:31 +0000
Subject: [PATCH] added clear channel assessment timeout. long to begin with.

---
 platform/msb430/contiki-conf.h |  5 +++--
 platform/msb430/dev/cc1020.c   | 12 +++++++++++-
 2 files changed, 14 insertions(+), 3 deletions(-)

diff --git a/platform/msb430/contiki-conf.h b/platform/msb430/contiki-conf.h
index 3bf86c7e6..332dd980b 100644
--- a/platform/msb430/contiki-conf.h
+++ b/platform/msb430/contiki-conf.h
@@ -24,14 +24,15 @@
 
 #define CC_CONF_REGISTER_ARGS		1
 #define CC_CONF_FUNCTION_POINTER_ARGS	1
-
 #define CC_CONF_INLINE			inline
-
 #define CC_CONF_VA_ARGS			1
 
 #define CCIF
 #define CLIF
 
+/* Clear channel assessment timeout for sending with the CC1020 radio. (ms) */
+#define CC1020_CONF_CCA_TIMEOUT		50
+
 // Clock
 typedef unsigned short clock_time_t;
 #define CLOCK_CONF_SECOND		100
diff --git a/platform/msb430/dev/cc1020.c b/platform/msb430/dev/cc1020.c
index 28f967c1e..675e0a7a5 100644
--- a/platform/msb430/dev/cc1020.c
+++ b/platform/msb430/dev/cc1020.c
@@ -214,6 +214,8 @@ cc1020_set_power(uint8_t pa_power)
 int
 cc1020_send(const void *buf, unsigned short len)
 {
+  int try;
+
   if (cc1020_state == CC1020_OFF)
     return -2;
 
@@ -237,7 +239,15 @@ cc1020_send(const void *buf, unsigned short len)
 
   // Wait for the medium to become idle.
   if (cc1020_carrier_sense()) {
-    while (cc1020_carrier_sense());
+    for (try = 0; try < CC1020_CONF_CCA_TIMEOUT; try++) {
+      MS_DELAY(1);
+      if (!cc1020_carrier_sense()) {
+	break;
+      }
+    }
+    if (try == CC1020_CONF_CCA_TIMEOUT) {
+      return -3;
+    }
 
     // Then wait for a short pseudo-random time before sending.
     clock_delay(100 * ((random_rand() + 1) & 0xf));