-// here we introduce an error
-generic module Alarm32khzTo62500hzTransformC()
+/*
+ * Copyright (c) 2008, Technische Universitaet Berlin
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, 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 -------------------------------------------------------------
+ * $Date$
+ * @author Jan Hauer <hauer@tkn.tu-berlin.de>
+ * ========================================================================
+ */
+
+module Alarm32khzTo62500hzTransformC
+
{
- provides interface Alarm<T62500hz,uint32_t> as Alarm;
- uses interface Alarm<T32khz,uint32_t> as AlarmFrom;
+ provides interface Alarm<T62500hz,uint32_t> as Alarm[ uint8_t num ];
+ uses interface Alarm<T32khz,uint32_t> as AlarmFrom[ uint8_t num ];
}
implementation
{
- async command void Alarm.start(uint32_t dt){ call AlarmFrom.start(dt >> 1);}
- async command void Alarm.stop(){ call AlarmFrom.stop();}
- async event void AlarmFrom.fired(){ signal Alarm.fired();}
- async command bool Alarm.isRunning(){ return call AlarmFrom.isRunning();}
- async command void Alarm.startAt(uint32_t t0, uint32_t dt){ call AlarmFrom.startAt(t0 >> 1, dt >> 1);}
- async command uint32_t Alarm.getNow(){ return call AlarmFrom.getNow() << 1;}
- async command uint32_t Alarm.getAlarm(){ return call AlarmFrom.getAlarm() << 1;}
- default async event void Alarm.fired(){}
+
+ /**
+ * TelosB lacks a clock that satisfies the precision and accuracy
+ * requirements of the IEEE 802.15.4 standard (62500 Hz, +-40 ppm).
+ * As a workaround, we cast one tick of the 32768 Hz clock to two
+ * IEEE 802.15.4 symbols, which introduces a small (5%) error.
+ * As a consequence the timing of the beacon interval and slotted
+ * CSMA-CA algorithm is not standard-compliant anymore.
+ */
+
+#warning "Warning: MAC timing is not standard compliant!"
+
+ async command void Alarm.start[ uint8_t num ](uint32_t dt){ call AlarmFrom.start[num](dt >> 1);}
+ async command void Alarm.stop[ uint8_t num ](){ call AlarmFrom.stop[num]();}
+ async event void AlarmFrom.fired[ uint8_t num ](){ signal Alarm.fired[num]();}
+ async command bool Alarm.isRunning[ uint8_t num ](){ return call AlarmFrom.isRunning[num]();}
+ async command uint32_t Alarm.getAlarm[ uint8_t num ](){ return call AlarmFrom.getAlarm[num]() << 1;}
+
+ async command uint32_t Alarm.getNow[ uint8_t num ](){
+ // this might shift out the most significant bit
+ // that's why Alarm.startAt() is converted to a Alarm.start()
+ return call AlarmFrom.getNow[num]() << 1;
+ }
+
+ async command void Alarm.startAt[ uint8_t num ](uint32_t t0, uint32_t dt){
+ // t0 occured before "now"
+ atomic {
+ uint32_t now = call Alarm.getNow[num](), elapsed;
+ if (t0 < now)
+ elapsed = now - t0;
+ else
+ elapsed = ~(t0 - now) + 1;
+ if (elapsed > dt)
+ dt = elapsed;
+ dt -= elapsed;
+ call Alarm.start[num](dt);
+ }
+ }
+
+ /******************** Defaults ****************************/
+
+ default async command void AlarmFrom.start[ uint8_t num ](uint32_t dt){ }
+ default async command void AlarmFrom.stop[ uint8_t num ](){ }
+ default async command bool AlarmFrom.isRunning[ uint8_t num ](){ return FALSE;}
+ default async event void Alarm.fired[ uint8_t num ](){}
+ default async command void AlarmFrom.startAt[ uint8_t num ](uint32_t t0, uint32_t dt){ }
+ default async command uint32_t AlarmFrom.getNow[ uint8_t num ](){ return 0;}
+ default async command uint32_t AlarmFrom.getAlarm[ uint8_t num ](){ return 0;}
}
projects / tinyos-2.x.git / blobdiff