TKN15.4 "platform glue code" for the TelosB platform (see tinyos-2.x/tos/lib/mac...

[tinyos-2.x.git] / tos / platforms / telosb / mac / tkn154 / TKN154TimingP.nc

diff --git a/tos/platforms/telosb/mac/tkn154/TKN154TimingP.nc b/tos/platforms/telosb/mac/tkn154/TKN154TimingP.nc
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+/*
+ * Copyright (c) 2008, Technische Universitaet Berlin
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without 
+ * extraification, are permitted provided that the following conditions 
+ * are met:
+ * - Redistributions of source code must retain the above copyright notice,
+ *   this list of conditions and the following disclaimer.
+ * - Redistributions in binary form must reproduce the above copyright 
+ *   notice, this list of conditions and the following disclaimer in the 
+ *   documentation and/or other materials provided with the distribution.
+ * - Neither the name of the Technische Universitaet Berlin nor the names 
+ *   of its contributors may be used to endorse or promote products derived
+ *   from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 
+ * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 
+ * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+ * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT 
+ * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, 
+ * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED 
+ * TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, 
+ * OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY 
+ * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE 
+ * USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * - Revision -------------------------------------------------------------
+ * $Revision$
+ * $Date$
+ * @author: Jan Hauer <hauer@tkn.tu-berlin.de>
+ * ========================================================================
+ */
+
+/** 
+ * NOTE:
+ * In slotted CSMA-CA frames must be sent on backoff boundaries (slot width:
+ * 320 us). On TelosB the only clock source with sufficient accuracy is the
+ * external quartz, unfortunately it is not precise enough (32.768 Hz).
+ * Therefore, currently the following code is not even trying to achieve
+ * accurate timing. 
+ */
+
+#include "TKN154_platform.h"
+module TKN154TimingP
+{
+  provides interface CaptureTime;
+  provides interface ReliableWait;
+  provides interface ReferenceTime;
+  uses interface TimeCalc;
+  uses interface LocalTime<T62500hz>;
+}
+implementation
+{
+
+#define UWAIT1 nop();nop();nop();nop()
+#define UWAIT2 UWAIT1;UWAIT1
+#define UWAIT4 UWAIT2;UWAIT2
+#define UWAIT8 UWAIT4;UWAIT4
+
+  async command void CaptureTime.convert(uint16_t time, ieee154_reftime_t *localTime, int16_t offset)
+  {
+    // TimerB is used for capturing, it is sourced by ACLK (32768Hz),
+    // we now need to convert the capture "time" into ieee154_reftime_t.
+    // With the 32768Hz quartz we don't have enough precision anyway,
+    // so the code below generates a timestamp that is not accurate
+    // (deviating about +-50 microseconds; this could probably
+    // improved if we don't go through LocalTime)
+    uint16_t tbr1, tbr2, delta;
+    uint32_t now;
+    atomic {
+      do {
+        tbr1 = TBR;
+        tbr2 = TBR;
+      } while (tbr1 != tbr2); // majority vote required (see msp430 manual)
+      now = call LocalTime.get(); 
+    }
+    if (time < tbr1)
+      delta = tbr1 - time;
+    else
+      delta = ~(time - tbr1) + 1;
+    *localTime = now - delta*2 + offset;
+  }
+
+  async command void ReliableWait.busyWait(uint16_t dt)
+  {
+    uint32_t start = call LocalTime.get();
+    while (!call TimeCalc.hasExpired(start, dt))
+      ;
+  }
+
+  async command void ReliableWait.waitCCA(ieee154_reftime_t *t0, uint16_t dt)
+  {
+    while (!call TimeCalc.hasExpired(*t0, dt))
+      ;
+    signal ReliableWait.waitCCADone();
+  }
+
+  async command void ReliableWait.waitTx(ieee154_reftime_t *t0, uint16_t dt)
+  {
+    while (!call TimeCalc.hasExpired(*t0, dt))
+      ;
+    signal ReliableWait.waitTxDone();
+  }
+
+  async command void ReliableWait.waitRx(ieee154_reftime_t *t0, uint16_t dt)
+  {
+    while (!call TimeCalc.hasExpired(*t0, dt))
+      ;
+    signal ReliableWait.waitRxDone();
+  }
+ 
+  async command void ReferenceTime.getNow(ieee154_reftime_t* reftime, uint16_t dt)
+  {
+    *reftime = call LocalTime.get();
+  }
+
+  async command uint32_t ReferenceTime.toLocalTime(ieee154_reftime_t* refTime)
+  {
+    return *refTime;
+  } 
+
+}