You probably need to read the lessons a bit closer
and learn a little more C. Look at wikibooks for a
good C primer.
In this particular case, presuming that the receive()
is actually getting an XDataMsg, the commented code
is trying to get a pointer to the whole message but
going about it a bit wrongly. The function is getting
a pointer not a full structure... TOS_MsgPtr has a
hidden "*" in it... Try this instead:
event TOS_MsgPtr ReceiveMsg.receive(TOS_MsgPtr msg)
{
XDataMsg *payload;
uint16_t constant;
payload = (XDataMsg*)(msg->data);
constant = payload->constant;
}
Once you can understand what each of those lines means
(which is just basic C and pointers) it should not be
too hard to do the rest.
MS
Xavi Colomer wrote:
> Hi people!
>
> I'm in a project to implement a network with some mica2 motes (one of
> them as a base station).I need to send a constant from base to sensors,
> but I can't take the data from the message I receive. I pick and modify
> the default lesson3 code that comes on PN2 and I add the following code:
>
> event TOS_MsgPtr ReceiveMsg.receive(TOS_MsgPtr msg){
> //atomic constant= msg->XDataMsg;
> return msg;
> }
> I have tried the commented text but doesn't work. The struct of the
> message received is:
>
> typedef struct XDataMsg{
> uint8_t board_id;
> uint8_t packet_id;
> uint8_t node_id;
> uint8_t rsvd;
> uint16_t vref;
> uint16_t constant;
> }__attribute__ ((packed)) XDataMsg;
>
> Thanks in advance.
>
>
> ------------------------------------------------------------------------
>
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