From ee2922b6fbec554c20510cf5a3fa4545bc8596f1 Mon Sep 17 00:00:00 2001
From: Jonathan Hui <jonhui@nestlabs.com>
Date: Wed, 6 Jul 2016 18:54:10 -0700
Subject: [PATCH] Add guard to avoid re-enabling the receiver. (#247)

---
 examples/platforms/cc2538/radio.c | 19 +++++++++++++------
 1 file changed, 13 insertions(+), 6 deletions(-)

diff --git a/examples/platforms/cc2538/radio.c b/examples/platforms/cc2538/radio.c
index 7d186b221..1b10b192d 100644
--- a/examples/platforms/cc2538/radio.c
+++ b/examples/platforms/cc2538/radio.c
@@ -85,15 +85,20 @@ typedef enum PhyState
 } PhyState;
 
 static PhyState sState;
+static bool sIsReceiverEnabled = false;
 
 void enableReceiver(void)
 {
-    // flush rxfifo
-    HWREG(RFCORE_SFR_RFST) = CC2538_RF_CSP_OP_ISFLUSHRX;
-    HWREG(RFCORE_SFR_RFST) = CC2538_RF_CSP_OP_ISFLUSHRX;
+    if (!sIsReceiverEnabled)
+    {
+        // flush rxfifo
+        HWREG(RFCORE_SFR_RFST) = CC2538_RF_CSP_OP_ISFLUSHRX;
+        HWREG(RFCORE_SFR_RFST) = CC2538_RF_CSP_OP_ISFLUSHRX;
 
-    // enable receiver
-    HWREG(RFCORE_SFR_RFST) = CC2538_RF_CSP_OP_ISRXON;
+        // enable receiver
+        HWREG(RFCORE_SFR_RFST) = CC2538_RF_CSP_OP_ISRXON;
+        sIsReceiverEnabled = true;
+    }
 }
 
 void disableReceiver(void)
@@ -109,6 +114,8 @@ void disableReceiver(void)
         // disable receiver
         HWREG(RFCORE_SFR_RFST) = CC2538_RF_CSP_OP_ISRFOFF;
     }
+
+    sIsReceiverEnabled = false;
 }
 
 void setChannel(uint8_t channel)
@@ -358,7 +365,7 @@ void readFrame(void)
 
     // check for rxfifo overflow
     if ((HWREG(RFCORE_XREG_FSMSTAT1) & RFCORE_XREG_FSMSTAT1_FIFOP) != 0 &&
-        (HWREG(RFCORE_XREG_FSMSTAT1) & RFCORE_XREG_FSMSTAT1_FIFO) != 0)
+        (HWREG(RFCORE_XREG_FSMSTAT1) & RFCORE_XREG_FSMSTAT1_FIFO) == 0)
     {
         HWREG(RFCORE_SFR_RFST) = CC2538_RF_CSP_OP_ISFLUSHRX;
         HWREG(RFCORE_SFR_RFST) = CC2538_RF_CSP_OP_ISFLUSHRX;