If by "that" you mean casting something to be a pointer: (uint8_t *)
and then dereferencing it: RSSI = *(pointer)
Sure you can do it...on most real computers you'll usually get
a BUSERR or SEGFAULT, but sometimes you'll get lucky...on our
u-controllers it'll probably just generate junk unless it just
happens to point to some valid bit of the tiny memory we have...
I just looked (shall we say, more carefully) at your advice:
>>>>> uint16_t * stren = (uint16_t *) msg->strength;
>>>>> RSSI = stren[0];
and my own mushy-brained-belief is that it's basically doing
the same thing -- treating "strength" as a pointer and then
derefing it using the array syntax. Plus I wasn't paying
attention to sizes and strength is definitely a 16 bit int,
not 8 as the original poster was trying to do.
Anyway, hopefully what I said to do actually worked right...
keep up the good work
MS
Benjamin Madore wrote:
MS,
I thought you could do that. I was staring at code all week and my brain had
turned to mush.
-Ben
On Fri, June 29, 2007 1:16 pm, Michael Schippling said:
I think the original problem is this:
RSSI=*((uint8_t *)recv_packet->strength);
which is treating "strength" as a pointer and de-referencing it. What you
want is:
RSSI = recv_packet->strength;
Then do all the arcana of converting to db which is covered in
these other answers...
As to the funny-ness with ADC get and ready, the underlying
radio code calls the ADC0 get right after it receives a messsage. So you
probably overloaded their ready() with yours.
MS
Benjamin Madore wrote:
On Fri, June 29, 2007 11:43 am, Bernardo Avila Pires said:
Wasn't the value in msg->strenght some untransformed one? I remember
having read that a function should be applied to it in order to obtain
RSSI.
Only if you want decibels or some other unit. The number given is the
internal measurement scale, plenty useful for direct comparison.
2007/6/29, Benjamin Madore <[EMAIL PROTECTED]>:
msg->strength is uint16_t
You're only getting half the number.
Besides,
uint16_t * stren = (uint16_t *) msg->strength;
RSSI = stren[0];
should be easier to read. I think there is an even more elegant way to
state
this, but I don't care enough to find it. Avoid doing multiple things
on
one
line until your sure all your bugs are gone. (I.E. Never do multiple
things
on one line.) Let the compiler optimize.
Your RSSI should be between 400 and 0. It is interpreted as a negative
number, with 400 being quiet, and 0 being very loud.
You can also wire to ADC.ADC[TOS_ADC_CC_RSSI_PORT] and call
"ADC.getData();"
which provides the event "ADC.dataReady(uint16_t data);" like you said.
dataReady is singled every time anyone calls getData. The radio stack
does
this a lot. You have to filter out your calls. I might suggest a lock.
When you call getData, set a boolean to true, and when you have read
one
value in dataReady, set it to false.
-Ben
On Fri, June 29, 2007 10:21 am, CASTEL Myriam said:
Hello,
I'm trying to obtain the RSSI value with Mica2 motes.
-I programmed a component which stores the strength of a TOSMsg
received:
RSSI=*((uint8_t *)recv_packet->strength);
But this doesn't give reasonnable results. I think this method is only
for the micaz? Isn't it?
- In the documentation, I saw that the RSSI was given by the channel 0
in mica2.
I tried to sample channel 0 with in configuration file: MyApp.ADC->
ADCC.ADC[0];
in module file: event TOS_MsgPtr ReceiveMsg.receive(TOS_MsgPtr
recv_packet){
call ADC.getData();
return recv_packet;
}
async event result_t ADC.dataReady(uint16_t data) {
atomic pack->xData.datap1.value = data;
post sendMsg();
return SUCCESS;
}
but the problem is that the mote execute ADC.dataReady even if getData
wasn't called. Maybe I have forgotten some elements as:
call
ADC.Control.bindPort(TOS_ADC_CC_RSSI_PORT,TOS_ACTUAL_CC_RSSI_PORT)
or other things.
Can you help me to obtain RSSI value (with channel 0 or other)? If you
have the code to compute RSSI, can you send it to me?
I'm sorry for this question but I'm new and I don't find the answers
in
the documentation provided by Crossbow.
Thanks
--
The difference between the right word and the almost right word is really
a
large matter- it's the difference between a lightning bug and the
lightning.
-Twain
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