Hi Urs, You have to call Packet.clear() to initialize the packet! On the first Send.send() call the radio stack realizes that your packet has not been initialized yet (either with Packet.clear() or has been received via the same radio stack), so it implicitly calls Packet.clear() which clears your ack request flag in the metadata. On the second call everything is fine, since your packet is properly initialized for the radio stack.
Imagine, if your packet came from the serial stack, then it would contain garbage in the metadata section, so that is why the radio stack cannot trust that packet, and the empty packet is similar. Best, Miklos On Thu, May 14, 2009 at 11:45 AM, Urs Hunkeler <[email protected]> wrote: > Hi, > > I have a simple program that sends messages requesting an ack. On > tmotes, this program works as expected, but on Iris motes the first > message after turning the application on is not acknowledged. Using a > sniffer shows that the ack is not sent. Further investigation showed > that the ack does not seem to be requested. In particular, when the mote > acknowledging messages is a Tmote and the mote sending the messages is > an Iris mote, the first message does not get an ack, but if the roles > are inversed, the first message gets acknowledged. > > The program code for the test application is below. If the node id is 0, > the mote will not do anything special but just acknowledge the messages > it receives (implicitly). If the node id is not 0, then the mote will > periodically send messages and check for acknowledgments. The expected > behavior is that both LEDs (red and green) turn on simultaneously at the > very beginning (red toggles when sending messages and green is turned on > if an ack is received, and off otherwise). > > Is there a bug with the Iris radio implementation that the first message > is not acknowledged? Or did I implement something wrong? > > Thanks, > Urs > > ------------------------ > #include "test.h" > > module TestC { > uses interface Leds; > uses interface Boot; > uses interface SplitControl as RadioControl; > uses interface AMSend as Send; > uses interface Timer<TMilli> as Timer; > uses interface PacketAcknowledgements as Ack; > } > implementation { > message_t rpacket; > > event void Boot.booted() { > call RadioControl.start(); > } > > event void Timer.fired() { > error_t error; > TestMsg* msg; > > call Leds.led0Toggle(); > > msg = (TestMsg*)call Send.getPayload(&rpacket, sizeof(TestMsg)); > if(msg == NULL) { > call Leds.led2On(); > return; > } > > msg->data = TOS_NODE_ID; > > error = call Ack.requestAck(&rpacket); > if(error != SUCCESS) { > call Leds.led2On(); > return; > } > > error = call Send.send(0, &rpacket, sizeof(TestMsg)); > if(error != SUCCESS) { > call Leds.led2On(); > } > } > > event void RadioControl.startDone(error_t error) { > if(error == SUCCESS) { > if(TOS_NODE_ID > 0) { > call Timer.startPeriodic(1024); > } > } else { > call Leds.led2On(); > } > } > > event void Send.sendDone(message_t* msg, error_t error) { > if(error != SUCCESS) { > call Leds.led2On(); > } > if(call Ack.wasAcked(msg)) { > call Leds.led1On(); > } else { > call Leds.led1Off(); > } > } > > event void RadioControl.stopDone(error_t error) { > if(error != SUCCESS) { > call Leds.led2On(); > } > } > } > _______________________________________________ > Tinyos-help mailing list > [email protected] > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help > _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
