Hi all,
Thanks for the the replies David, Michael and Eric.
Unfortunately my background doesn't allow me to go up and running with RF as
fast as I would like to. I am still trying to figure out where is the part of
the code where CSMA (collision detection?) is implemented with the CC1000. And
not only that. Is PLL tuning (or the crystal calibration) necessary how often?
Everytime that the reference frequency changes (due to freq hopping for
example?). Steep temperature variation? This tuning takes 34ms of time and I
could get rid of it if I am listening just to one channel correct?
Besides that, something that I suppose is straightforward for you: how can I
estimate the baudrate based on the rx baseband signal, tx frequency deviation
("1"=> fc+df, "0"=>fc-df)? Even knowing that this configurations are registered
selectable and independently. And where I set the number of bits for the
preamble and the minimum acknowledged required??
For Manchester, I think I'll just leave it for now.
Thanks guys for the feedback,
Edgar Charry
From: [EMAIL PROTECTED]: [EMAIL PROTECTED]; [EMAIL PROTECTED]; [EMAIL
PROTECTED]: [EMAIL PROTECTED]: RE: [Tinyos-help] Pumping up bandwidth -
Mica2Dot/Mica2Date: Mon, 14 Apr 2008 18:28:17 -0700
Manchester encoding. And CSMA.
Manchester halves the throughput. Instead of 76.8 kbps, Manchester will force
your radio to transmit at 38.4 kbps. Getting rid of Manchester may not be a
simple task: it’s there to zero out the energy seen by a receiver, so it can
easily know that it’s receiving valid data.
CSMA causes your transmitter to share the channel with other transmitters, and
the channel checks may be spaced relatively far apart which dramatically
decreases throughput.
The CC1000 radio could be a really kick-ass radio if it were implemented
properly. The ability to easily enable/disable Manchester, CSMA, etc. (among
other things) would really improve its situation. The CC1000 radio is much
more energy efficient than the CC2420 radio, and can transmit a lot farther
than the CC2420 radio (but that broken matching network on mica2’s and
especially mica2dot’s really cause everyone problems). It’s unfortunate so
many people dismiss the CC1000 radio as obsolete, when it could really
outperform their radios in terms of efficiency and range (not throughput).
29 bytes is only a software (and RAM) limitation. Increase it by doing a
CFLAGS+=-DTOSH_DATA_LENGTH=50 or something in your Makefile. Removing
unnecessary fields from the CC1000 header will decrease the header:payload
ratio and increase payload throughput.
If you’re thinking about rolling your own hardware, you should really be using
CC1100 or CC2500 radios for any wireless application that doesn’t require
802.15.4 compatibility: http://docs.tinyos.net/index.php/CC1100/CC2500
-David
From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Edgar
CharrySent: Monday, April 14, 2008 3:57 PMTo: [EMAIL PROTECTED]; Eric KellerCc:
[EMAIL PROTECTED]: Re: [Tinyos-help] Pumping up bandwidth - Mica2Dot/Mica2
Hi all, Thanks for your prompt replies. Unfortunately I that link didn't let
me through. In fact I am still trying to undestand them, as I wasn't aware of
that limitation of 33-50ms of the Mica2's! You are saying that the maximum
bandwidth my app should require is 0-25Hz so that I have a nice reconstruction
of my wave, due to HW limitations? I knew that the CC1000 has a maximum
bandwidth of 76.8kbps and of course due to EEPROM readings/writings, CPU
instructions, ADC's measurements etc. this number should decrease. But I wasn't
expecting a final bandwidth of 30pckts/s!!! In fact, I thought there were
problems related to the TOSBase. My app requirement need at least 100Hz
(Mica2's transmission needed thus 200 pckts/s), which is necessary to track a
complete gait cycle using acc and gyros with good definition. What is the most
critical factor in the Mica2's that blow the transmission rate so bad? Does
this happen with the Mica2Dot too? Data compression (sample with a higher freq,
store in the RAM and then send the whole bunch of bytes) has a limitation of 29
bytes due to TinyOS, correct? Thanks guys for the good info.Cheers,Edgar
Charry> Date: Mon, 14 Apr 2008 12:20:38 -0600> From: [EMAIL PROTECTED]> To:
[EMAIL PROTECTED]> CC: tinyos-help@millennium.berkeley.edu> Subject: Re:
[Tinyos-help] Pumping up bandwidth - Mica2Dot/Mica2> > Well, since people are
quoting my second source messages, have a look at:>
http://www.etantdonnes.com/Motes/report_mica2/> (which seems to be down right
now but will hopefully be back soon...).> > However my message
speed/reliability measurements use only the standard> GenericComm and TOS1
code. I think the OP was trying to fiddle timeouts> and backoffs to speed
things up further. Data mining of the help list> should turn up some more
useful advice in this respect.> > MS> > Eric Keller wrote:> > There is a limit
to how many packets you can send with a mica2 which you are> > at or above. You
probably want to lower your bandwidth requirements somehow.> > See this
message:> >
https://www.millennium.berkeley.edu/pipermail/tinyos-help/2008-April/032464.html>
> > > Eric> > > > > > On Mon, Apr 14, 2008 at 4:59 AM, Edgar Charry <[EMAIL
PROTECTED]> wrote:> >> Hi all,> >>> >> I am trying to pump my packet
transmission up between a Mica2Dot and a> >> Mica2 to at least 200Hz
[pckts/s].> >>> >> I've decreased the timer constant to a bottleneck of 33ms
(30 pckts/s) that> >> pratically executes a round of ADC measurements and send
the packet.> >> Decreasing from this point doesn't give me more bandwidth.
However, my> >> packet is 14bytes long (the TinyOS header + just a couple of
adc> >> measurements + CRC).> >>> >> I suspect that this 33ms (parsed time
stamps from XSniffer) are limited to> >> the TOSBase.nc on the Mica2. I suspect
that the PLL of the Mica2 is> >> listening through channels and is not locked
to the transmitter's one. Every> >> loop thus should take 33ms.> >>> >>
Actually, I haven't been through the CC1000 conf/mod components though, but> >>
I reckon with your experience this can be solved easily.> >> Cheers,> >> Edgar
Charry> >>> >> ________________________________> >> Explore the seven wonders
of the world Learn more!> >> _______________________________________________>
>> Tinyos-help mailing list> >> Tinyos-help@millennium.berkeley.edu> >>
https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help> >>> >
_______________________________________________> > Tinyos-help mailing list> >
Tinyos-help@millennium.berkeley.edu> >
https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help> > --
> Platform: WinXP/Cygwin> TinyOS version: 1.x, Boomerang> Programmer: MIB510>
Device(s): Mica2, MicaZ, Tmote> Sensor board: homebrew> >
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