Re: [Tinyos-help] Sampling Noise level
Sean,I am assuming that you want to sample the noise in the RF frequency band. You can use the RSSI signal from the CC1000 radio chip to get a good idea of what the noise level is at. This signal is a current output that isconnected to gnd across a resistor (and capacitor for filtering), so that the mote can sample the signal as avoltage. You may want to checkout the CC1000 datasheet as well as whateverxbow says about it.Simply sample this channel (as far as you can) to record the signal level as measured by the radio chip. What I have done to gauge the noise (using Tmote Sky motes) is to read the RSSI register from the CC2420 (not an analog signal) and then send the data to a host computer across the UART. Performing this simple testing outdoors and indoors makes it clear very quickly why the radios tend to perform better outdoors.Regards,Matt[EMAIL PROTECTED] wrote: -To: tinyos-help@Millennium.Berkeley.EDUFrom: Sean Casey [EMAIL PROTECTED]Sent by: [EMAIL PROTECTED]Date: 06/12/2006 10:38PMSubject: [Tinyos-help] Sampling Noise levelHi everyone,Is there a way to sample the noise in a given environment? I was interested in having a mote (mica2) just monitor the noise level, and not send or receive any packets. I checked the archives and I couldn't find anything on this, so if anyone had any ideas or could point me in the right direction, I'd appreciate it.Thanks,Sean___Tinyos-help mailing listTinyos-help@Millennium.Berkeley.EDUhttps://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help___ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
[Tinyos-help] RSSI_VAL
Hi all, I am working with the localization of micaz motes (with the 1.1.7version of TinyOS), and for it, I need to know the RSSI value messured. At this moment, I am able to read the value, and see that when I separate the motes, this value dicreases. But which are the unit of this value ? How can I do the conversion? The datasheet of CC2420 gives me this formula to obtain the power in dBm: P=RSSI_VAL+RSSI_OFFSET RSSI_OFFSET is -45dBm, so, RSSI_VAL must be in dB if I want to obtain the power in dBm. Can anyone explain me how can I convert my data read to RSSI_VAL in dB? Thank you in advance, Andrés _ Descubre la descarga digital con MSN Music. Más de un millón de canciones. http://music.msn.es/ ___ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
Re: [Tinyos-help] RSSI_VAL
Hi, I have an application that copies the msg-strength and saving it in an uint8_t data: uint8_t msg-data[4]=msg-strength then with my own xlisten, I visualize the strength. Thanks for your attention, Andrés From: Hui KANG [EMAIL PROTECTED] To: [EMAIL PROTECTED] Subject: Re: [Tinyos-help] RSSI_VAL Date: Tue, 13 Jun 2006 09:52:01 -0500 (CDT) Which tool did you use to see the value, listen or others? Thanks. Hui Kang On 6/13/2006, Andres Aberasturi [EMAIL PROTECTED] wrote: Hi all, I am working with the localization of micaz motes (with the 1.1.7version of TinyOS), and for it, I need to know the RSSI value messured. At this moment, I am able to read the value, and see that when I separate the motes, this value dicreases. But which are the unit of this value ? How can I do the conversion? The datasheet of CC2420 gives me this formula to obtain the power in dBm: P=RSSI_VAL+RSSI_OFFSET RSSI_OFFSET is -45dBm, so, RSSI_VAL must be in dB if I want to obtain the power in dBm. Can anyone explain me how can I convert my data read to RSSI_VAL in dB? Thank you in advance, Andrés _ Descubre la descarga digital con MSN Music. Más de un millón de canciones. http://music.msn.es/ ___ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help _ Acepta el reto MSN Premium: Correos más divertidos con fotos y textos increíbles en MSN Premium. Descárgalo y pruébalo 2 meses gratis. http://join.msn.com?XAPID=1697DI=1055HL=Footer_mailsenviados_correosmasdivertidos ___ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
Re: [Tinyos-help] Tmote Sky ACK
SP has an option to request reliability, which will let you know if the packet was acknowledged or not. Please see the SPSend interface documentation in /opt/moteiv/doc/nesdoc or read the SP paper at www.polastre.com/pubs.html -Joe On 6/12/06, giovanni gamba [EMAIL PROTECTED] wrote: Hi all, does anybody knows how can i use ACKED tx and rx on Tmote Sky MOTES? Is it possible to set it up at runtime, like the rf power or the rf channel (i think using the CC2420ControlM module)? And another thing... does every trasmission use the SP components?Can i modify parameters at this level or it's better not? Thank you very much Giovanni ___ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help ___ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
[Tinyos-help] is possible with TinyViz?
Hi all, i'd like to work with packages bigger than 29 bytes. So i modified in AM.h TOSH_DATA_LENGTH (but no more of 100 bytes, cause there are many warnings showed by the compiler). So the question is: does anyone know how to see in TinyViz all the data bytes? cause by default you can see only 29 bytes with debug messages. If and where there is something that has to be modified, please advise me! Thanks for your availability, cheers Daniele ___ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
RE: [Tinyos-help] Tmote Sky ACK
The easiest thing is to use GenericCom, you can enable ACk by call enableACK() command. For SP, maybe it is a good stuff, but it will take many efforts to understand the mechanism, since there is no good documentation on that -- the SP paper ishigh level, not much help to programming. From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of giovanni gambaSent: Monday, June 12, 2006 4:53 PMTo: tinyos-helpSubject: [Tinyos-help] Tmote Sky ACK Hi all,does anybody knows how can i use ACKED tx and rx on Tmote Sky MOTES?Is it possible to set it up at runtime, like the rf power or the rf channel (i think using the CC2420ControlM module)?And another thing... does every trasmission use the SP components?Can i modify parameters at this level or it's better not?Thank you very muchGiovanni ___ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
Re: [Tinyos-help] using the hardware multiplier on msp430 for FFT
On Jun 11, 2006, at 9:41 AM, Matthew J Whelan wrote: I don't think there is an interface, but using the hardware multiplier is a rather easy task to figure out. I haven't used it for FFT, but I have implemented digital filtering without any issues. You should check out the TI application note on the hardware multiplier for info on how to use it and source code for FFT calculations: http://focus.ti.com/lit/an/slaa042/slaa042.pdf When compiling for MSP430 platforms, the TinyOS build chain tells gcc to not use the multiply instruction. There's nothing wrong with the instruction; rather, gcc has some bugs when generating code that uses it. Therefore, I'd guess that assembly hacking would work fine, but trying to do it through C will run into issues. Phil ___ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
Re: [Tinyos-help] NesC and TinyOS
On Jun 12, 2006, at 7:29 AM, Andres Aberasturi wrote:
Hi all,
We have been working with TinyOs and NesC some few months, but we
still have some doubts. We want to ask you the following three
questions:
1.- In some places, we have read that events can call commands,
post tasks and signal other events. Also, we have read that
commands can call lower level commands. Then, a command cannot post
a task? or signal an event? is it right? We thought command can do it.
The only operation that issues a warning is when an async function
calls a sync function. For simplicity, sync functions are only safe
to call when the root of the call graph is a task. Async functions
can also have interrupt handlers are their root.
In practice, it is bad practice to signal an event (signal )
inside a command. There is nothing that prevents you from doing so,
however. It is bad practice because it can easily lead to infinite
call loops. For example:
call Foo.send();
event void Foo.sendDone();
commmand void Foo.send() {
signal Foo.sendDone();
}
The TinyOS programming manual goes into detail on this and other good/
bad programming practices.
2.- We have read that there are two level scheduling: events and
tasks. We know TinyOs scheduler manages tasks which are posted, so
does TinyOs scheduler manage events? or are events managed like
commands?
The distinction is sync/async. The term event was overloaded in the
original TinyOS paper to mean both callback and interrupt. The
command/event distinction means the former, the task/event
distinction means the latter. The nesC paper and the TinyOS
programming guide are good resources for learning about the details.
3.- If you have a task posted, could you post the same task other
time? We mean if we have a task in the task qeue, could we post the
same task again? Perhaps it is a simple question, but we think it
is possible that if the task is in the task qeue, we couldn't post
it again.
This depends on what version of TinyOS you're using. In 1.x, a
single task can have multiple outstanding posts in the task queue. In
2.x, a task can only have one outstanding post. This latter behavior
turns out to have a lot of nice isolation and fairness properties.
TEP 106 has a good discussion of the tradeoffs.
Phil
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Re: [Tinyos-help] Help with simulators
On Jun 12, 2006, at 8:41 AM, Aditya Bhave wrote: Hello all, Does any one know of a good simulator (preferably on a Windows based PC) that one can use to develop applications using the motes. I do not have access to the actual hardware and would like to work on projects with simulations. TOSSIM and TinyViz are completely non- intuitive and not documented. For TOSSIM documentation, I'd recommend: 1) The TOSSIM tutorial (for how to use it) 2) The TOSSIM manual (for more details on its features) 3) The TOSSIM paper (for how it works) That being said, TOSSIM does require that you write TinyOS/nesC code. On the other hand, with a few exceptions mostly having to do with interrupt handling, TOSSIM is a pretty reasonable (but not perfect) TinyOS simulator. Phil ___ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
[Tinyos-help] make pc docs
Hello, make pc docs, produces the errors below, any help is appreciated, thanks Mikael $ make pc docs Making documentation for Blink on pc nesdoc /opt/tinyos-1.x/doc/nesdoc/pc -topdir=/home/TekMan -topdir=/ -fnesc-is- app -pthread -fnesc-nido-tosnodes=1000 -fnesc-simulate -Wall -Wshadow -DDEF_TOS _AM_GROUP=0x7d -Wnesc-all -target=pc -fnesc-cfile=build/pc/app.c -board=micasb - DIDENT_PROGRAM_NAME=\Blink\ -DIDENT_USER_ID=\TekMan\ -DIDENT_HOSTNAME=\mikm o-a24523d52\ -DIDENT_USER_HASH=0x4d8680c1L -DIDENT_UNIX_TIME=0x448e98c5L -DIDEN T_UID_HASH=0x23de3a57L Blink.nc nesc1: warning: invalid data in info.idx - ignoring remainder of file Error: c:\program files\ucb\att\graphviz\bin\dot.exe: can't open Files.UCB.cygwi n.opt.tinyos-1.x.apps.Blink.Blink.nc.if.gif Error: c:\program files\ucb\att\graphviz\bin\dot.exe: can't open cygdrive.c.Prog ram Error: c:\program files\ucb\att\graphviz\bin\dot.exe: can't open Files.UCB.cygwi n.opt.tinyos-1.x.apps.Blink.Blink.nc.if.dot Error: c:\program files\ucb\att\graphviz\bin\dot.exe: can't open Files.UCB.cygwi n.opt.tinyos-1.x.apps.Blink.Blink.nc.if.cmap Error: c:\program files\ucb\att\graphviz\bin\dot.exe: can't open cygdrive.c.Prog ram Error: c:\program files\ucb\att\graphviz\bin\dot.exe: can't open Files.UCB.cygwi n.opt.tinyos-1.x.apps.Blink.Blink.nc.if.dot assertion infile failed: file unparse.c, line 187 make: *** [docs_] Error 1 ___ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
RE: [Tinyos-help] NesC and TinyOS
Phil, I have read your TinyOS programming manual, and still have some doubt
regarding the data race conditions:
(1)
void foo()
{
c = d;
}
..
atomic
{
a = b;
foo();
}
...
First question is: does atomic protect the variable in both side. In this
example, are all variables (a,b,c,d) protected? Or just a and c are
protected.
Another question is, since async event can still interrupt the atomic
section (as you mention in the manual). Assume the following async event
comes after 'a=b' assignment: async event result_t ADC.dataReady(uint16_t
data) { a = data;}. What will happen? What would the excution order be?
(2) I notice many sample program does something like this:
async event result_t ADC.dataReady(uint16_t data) {
m_data = data;
post sendData();
return SUCCESS;
}
task void sendData() {
.
atomic dmsg-data = m_data; // assume dmsg will be modified here only
}
what's the usage of atomic here? Since task will not preempt itself. On the
other hand, the async event can preempt the task at any time (e.g., another
dataReady event comes before task sendData excutes). It seems to me there is
no difference whether there is atomic or not.
I notice some code like Oscope added atomic in dataReady, does it make
difference?
Thanks.
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of Philip
Levis
Sent: Tuesday, June 13, 2006 9:01 AM
To: Andres Aberasturi
Cc: tinyos-help@Millennium.Berkeley.EDU
Subject: Re: [Tinyos-help] NesC and TinyOS
On Jun 12, 2006, at 7:29 AM, Andres Aberasturi wrote:
Hi all,
We have been working with TinyOs and NesC some few months, but we
still have some doubts. We want to ask you the following three
questions:
1.- In some places, we have read that events can call commands, post
tasks and signal other events. Also, we have read that commands can
call lower level commands. Then, a command cannot post a task? or
signal an event? is it right? We thought command can do it.
The only operation that issues a warning is when an async function calls a
sync function. For simplicity, sync functions are only safe to call when the
root of the call graph is a task. Async functions can also have interrupt
handlers are their root.
In practice, it is bad practice to signal an event (signal ) inside a
command. There is nothing that prevents you from doing so, however. It is
bad practice because it can easily lead to infinite call loops. For example:
call Foo.send();
event void Foo.sendDone();
commmand void Foo.send() {
signal Foo.sendDone();
}
The TinyOS programming manual goes into detail on this and other good/ bad
programming practices.
2.- We have read that there are two level scheduling: events and
tasks. We know TinyOs scheduler manages tasks which are posted, so
does TinyOs scheduler manage events? or are events managed like
commands?
The distinction is sync/async. The term event was overloaded in the
original TinyOS paper to mean both callback and interrupt. The
command/event distinction means the former, the task/event
distinction means the latter. The nesC paper and the TinyOS
programming guide are good resources for learning about the details.
3.- If you have a task posted, could you post the same task other
time? We mean if we have a task in the task qeue, could we post the
same task again? Perhaps it is a simple question, but we think it
is possible that if the task is in the task qeue, we couldn't post
it again.
This depends on what version of TinyOS you're using. In 1.x, a
single task can have multiple outstanding posts in the task queue. In
2.x, a task can only have one outstanding post. This latter behavior
turns out to have a lot of nice isolation and fairness properties.
TEP 106 has a good discussion of the tradeoffs.
Phil
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Re: [Tinyos-help] NesC and TinyOS
On Jun 13, 2006, at 10:41 AM, David Gay wrote:
-- Forwarded message --
From: David Gay [EMAIL PROTECTED]
Date: Jun 13, 2006 10:41 AM
Subject: Re: [Tinyos-help] NesC and TinyOS
To: Adam [EMAIL PROTECTED]
Cc: [EMAIL PROTECTED]
On 6/13/06, Adam [EMAIL PROTECTED] wrote:
(1)
void foo()
{
c = d;
}
..
atomic
{
a = b;
foo();
}
...
First question is: does atomic protect the variable in both side.
In this
example, are all variables (a,b,c,d) protected? Or just a and c are
protected.
All variables are protected. Atomic statements are defined to be
serialisable, i.e., you can assume nothing else happens during the
execution of an atomic statement (and, in fact, they are simply
implemented by disabling interrupts...).
Another question is, since async event can still interrupt the atomic
section (as you mention in the manual).
Async events cannot interrupt atomic statements.
I think the confusion comes from the distinction between the
semantics of atomic (the theory) and what TinyOS does to achieve
these semantics (the practice).
David's first statement (serialisability) is how atomic behaves
semantically. As atomic sections are defined to be serializable, then
code in atomic section cannot be interrupted by code that modifies
anything which might alter its result: it must behave as if there
were no preemption, but rather a completely serial execution order.
In practice, the way TinyOS/nesC achieves this is to globally disable
interrupts. However, if it were running on more complex hardware
(e.g., with interrupt priority level disabling) then it *could* do
something more complex without violating its semantic requirements.
As the manual goes into, two atomic interrupts that never touch each
other could *in theory* preempt one another. In practice, however,
they do not.
Phil
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Re: [Tinyos-help] NesC and TinyOS
On 6/13/06, Adam [EMAIL PROTECTED] wrote: Page 39 Listing 4.24 in the Phil's manual says differently... I wish what you said is correct - easier to manage. Please clarify. Thanks. You're misinterpreting the text there. As Phil said in his answer, Listing 4.24 is an example of an optimisation where allowing async code to interrupt an atomic statement would have no detectable effects. But in cases where the effects would be detectable (i.e., if there is any shared state between the atomic statement and anything that interrupts it), such an optimisation would be illegal. It's all quite moot because we don't attempt to do such optimisations at this point. David Gay ___ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
Re: [Tinyos-help] Tmote Sky ACK
On 6/13/06, Adam [EMAIL PROTECTED] wrote: The easiest thing is to use GenericCom, you can enable ACk by call enableACK() command. For SP, maybe it is a good stuff, but it will take many efforts to understand the mechanism, since there is no good documentation on that -- the SP paper is high level, not much help to programming. This is completely not true. The paper describes the interfaces and their semantics. The documentation in Boomerang provides detailed nesdoc information on every interface and its uses. There is also a sample SP protocol called NetSync. You will find that SP is documented more than any other library in the tinyos-1.x tree. -Joe ___ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
[Tinyos-help] RSSI
I saw a few people talking about getting RSSI values. RSSI value seems to be zero when I use TOSSIM on a PC. Is that normal? Thanks Kn ___ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
Re: [Tinyos-help] RSSI
On Jun 13, 2006, at 12:15 PM, Keyan Mahadevan wrote: I saw a few people talking about getting RSSI values. RSSI value seems to be zero when I use TOSSIM on a PC. Is that normal? Yes; TOSSIM in 1.x doesn't model RF signal strength. (2.x does, but it does not yet make it accessible to applications). Phil ___ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
[Tinyos-help] Cannot compile TOSSIM 2.0!!
Hi, I recently upgraded to TinyOS 2, and I'm having trouble compiling for TOSSIM 2, this is what I get: $ make micaz sim mkdir -p build/micaz placing object files in build/micaz writing XML schema to app.xml compiling BlinkAppC to object file sim.o ncc -c -fPIC -o build/micaz/sim.o -g -O0 -tossim -fnesc-nido-tosnodes=1000 -fnes c-simulate -fnesc-nido-motenumber=sim_node\(\) -finline-limit=10 -Wall -Ws hadow -DDEF_TOS_AM_GROUP=0x7d -Wnesc-all -target=micaz -fnesc-cfile=build/micaz/ app.c -board=micasb -Wno-nesc-data-race BlinkAppC.nc -fnesc-dump=components - fnesc-dump=variables -fnesc-dump=constants -fnesc-dump=typedefs -fnesc-dump=inte rfacedefs -fnesc-dump=tags -fnesc-dumpfile=app.xml In file included from C:/cygwin/opt/tinyos-2.x/tos/lib/tossim/sim_mac.c:34, from C:/cygwin/opt/tinyos-2.x/tos/lib/tossim/tos.h:90: C:/cygwin/opt/tinyos-2.x/tos/lib/tossim/sim_gain.c:14: warning: declaration of ` link' shadows global declaration /usr/include/sys/unistd.h:97: warning: location of shadowed declaration C:/cygwin/opt/tinyos-2.x/tos/lib/tossim/sim_gain.c:20: warning: declaration of ` link' shadows global declaration /usr/include/sys/unistd.h:97: warning: location of shadowed declaration C:/cygwin/opt/tinyos-2.x/tos/lib/tossim/sim_gain.c: In function `sim_gain_alloca te_link': C:/cygwin/opt/tinyos-2.x/tos/lib/tossim/sim_gain.c:134: warning: declaration of `link' shadows global declaration /usr/include/sys/unistd.h:97: warning: location of shadowed declaration C:/cygwin/opt/tinyos-2.x/tos/lib/tossim/sim_gain.c: At top level: C:/cygwin/opt/tinyos-2.x/tos/lib/tossim/sim_gain.c:141: warning: declaration of `link' shadows global declaration /usr/include/sys/unistd.h:97: warning: location of shadowed declaration In file included from C:/cygwin/opt/tinyos-2.x/tos/chips/atm128/timer/sim/HplAtm 128Timer0AsyncC.nc:53, from C:/cygwin/opt/tinyos-2.x/tos/platforms/mica/AlarmCounterMi lliP.nc:30, from C:/cygwin/opt/tinyos-2.x/tos/platforms/mica/sim/HilTimerMi lliC.nc:41, from C:/cygwin/opt/tinyos-2.x/tos/system/TimerMilliP.nc:41, from C:/cygwin/opt/tinyos-2.x/tos/system/TimerMilliC.nc:40, from BlinkAppC.nc:46: In component `HplAtm128Counter0C': C:/cygwin/opt/tinyos-2.x/tos/chips/atm128/timer/sim/HplAtm128Counter0C.nc: In fu nction `timer0_overflow_handle': C:/cygwin/opt/tinyos-2.x/tos/chips/atm128/timer/sim/HplAtm128Counter0C.nc:31 1: w arning: declaration of `time' shadows global declaration /usr/include/time.h:49: warning: location of shadowed declaration In file included from C:/cygwin/opt/tinyos-2.x/tos/chips/atm128/timer/sim/HplAtm 128Timer0AsyncC.nc:58, from C:/cygwin/opt/tinyos-2.x/tos/platforms/mica/AlarmCounterMi lliP.nc:30, from C:/cygwin/opt/tinyos-2.x/tos/platforms/mica/sim/HilTimerMi lliC.nc:41, from C:/cygwin/opt/tinyos-2.x/tos/system/TimerMilliP.nc:41, from C:/cygwin/opt/tinyos-2.x/tos/system/TimerMilliC.nc:40, from BlinkAppC.nc:46: In component `HplAtm128CompareC': C:/cygwin/opt/tinyos-2.x/tos/chips/atm128/timer/sim/HplAtm128CompareC.nc: In fun ction `timer0_compare_handle': C:/cygwin/opt/tinyos-2.x/tos/chips/atm128/timer/sim/HplAtm128CompareC.nc:195 : wa rning: declaration of `time' shadows global declaration /usr/include/time.h:49: warning: location of shadowed declaration cc1: warning: -fPIC ignored for target (all code is position independent) . . . . And afterward everything fails! :-) Thanks in advance, Luis Enrique Palafox-Maestre ___ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
Re: [Tinyos-help] RSSI
A follow up question - is there any way I would be able to access the RSSI values in TOSSIM. Thanks KnOn 6/13/06, Philip Levis [EMAIL PROTECTED] wrote: On Jun 13, 2006, at 12:15 PM, Keyan Mahadevan wrote: I saw a few people talking about getting RSSI values. RSSI value seems to be zero when I use TOSSIM on a PC. Is that normal?Yes; TOSSIM in 1.x doesn't model RF signal strength. (2.x does, butit does not yet make it accessible to applications).Phil ___ Tinyos-help mailing list Tinyos-help@Millennium.Berkeley.EDU https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
Re: [Tinyos-help] NesC and TinyOS
On 6/13/06, Adam [EMAIL PROTECTED] wrote:
In the following common seeing code segment, I notice someone add 'atomic'
before 'm_data = data;' (such as OscilloscopeRF), someone does not (such as
Delta from Moteiv). Since another 'dataReady' interupt could come before
task sendData is excuted, it seems to me the first 'atomic' is not necessary
-- even if you have, the 'm_data' will be changed before sendData excuted.
Further more, if 'msg' will be modified here only, I even think the second
'atomic' is not necessary. Since one task will not preempt another task. In
other words, another post sendData will not excute until the current
sendData finish.
async event result_t ADC.dataReady(uint16_t data) {
atomic m_data = data;
post sendData();
return SUCCESS;
}
task void sendData() {
.
atomic msg-data = m_data; // assume msg will be modified here only
}
It seems to me that 'atomic' is useful only if there are a set of variables
- you want to keep the integrity of the variable set.
There is no guarantee that the write of a single variable is atomic.
In fact, on many mote platforms, reads or writes of anything larger
than a single variable are not atomic. So in the code above, a
dataReady interrupt at the wrong time could give a rather weird value
in m_data (assuming it is 16-bits it could get one byte from one
reading, and one byte from the next).
Also, if you write
x = x+1
there's only one variable. But you still get a data-race even if it is
a single byte. In fact, this is the classic example of a data-race...
Some people skip the atomic because either:
- they are more worried at the code size/execution time overhead of
atomic than the potential data race
- they know that the data-race won't occur for some other reason.
E.g., if I'm sampling once every 5 minutes, then there isn't going to
be a race on m_data (or if there is, there's clearly a very large
other problem ;-))
David Gay
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