huh, I hadn't considered that...good point. However...
at ~40 bytes (320 bits) per message, 100 messages is
32000 bits which _should_ still fit pretty easily
and I seem to remember pooping out around that rate.
Also I had the same-only-worse problem on the mica2,
needing a 20ms "retraction period" to minimize lost
messages. Has anyone actually measured the message
rate with a faster UART? Or between two micaz's
without UART overhead?
thx
MS
Cory Sharp wrote:
It is packet loss at the TOSBase where the serial port operating at
56kbps cannot keep up with the radio operating up to 250kbps. You could
try chaning the UART baudrate:
http://www.moteiv.com/community/Change_the_default_UART_baud_rate .
Cory
On 10/16/06, *harish prabhu* < [EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
Hi folks,
I find that on Tmotes (tinyos 1.x - latest CVS files for
CC2420RadioM.nc and CC2420RadioC.nc)
there is significant packet loss (while sending) under the
following conditions :
a) There is only one mote on the channel
b) Multiple packets are sent one after the other.
c) The packets are sent by posting a task in the send.SendDone of
the previous packet.The posted task calls Send.send.
d) The Radio does not return FAIL in the Send.sendDone
The packet loss rate increases with size of the packets.
I changed CntToRfm(Counter.nc <http://counter.nc/> ) to send 3
packets in a manner described above.
I also hacked IntToRfmM.nc to send a packet of size 44
(including TOS header) - with dummy bytes
and changed the TOSH_DATA_LENGTH to 60.
I wonder if this is a bug in the CC2420 radio library.
Adding a delay after Send.sendDone seems to reduce the packet loss.
I think this is not a problem with TOSBase missing packets -
because when
I changed CntToRfm to send a packet every 20 ms, TOSBase still did
not seem to
be losing any packets.
Here is the TOSBase log:
SAPP: 1E 01 08 30 FF FF FF FF 04 7D 30 07 01 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00 00
SAPP: 1E 01 08 31 FF FF FF FF 04 7D 31 07 01 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00
SAPP: 1E 01 08 32 FF FF FF FF 04 7D 32 07 01 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00
SAPP: 1E 01 08 33 FF FF FF FF 04 7D 33 07 01 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00
SAPP: 1E 01 08 35 FF FF FF FF 04 7D 35 07 01 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00
SAPP: 1E 01 08 37 FF FF FF FF 04 7D 37 07 01 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00
SAPP: 1E 01 08 39 FF FF FF FF 04 7D 39 07 01 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00
SAPP: 1E 01 08 3B FF FF FF FF 04 7D 3B 07 01 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00
SAPP: 1E 01 08 3D FF FF FF FF 04 7D 3D 07 01 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00
SAPP: 1E 01 08 3F FF FF FF FF 04 7D 3F 07 01 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00
SAPP: 1E 01 08 40 FF FF FF FF 04 7D 40 07 01 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00
SAPP: 1E 01 08 41 FF FF FF FF 04 7D 41 07 01 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00
SAPP: 1E 01 08 42 FF FF FF FF 04 7D 42 07 01 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00
SAPP: 1E 01 08 44 FF FF FF FF 04 7D 44 07 01 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00
SAPP: 1E 01 08 45 FF FF FF FF 04 7D 45 07 01 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00
SAPP: 1E 01 08 46 FF FF FF FF 04 7D 46 07 01 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00
SAPP: 1E 01 08 47 FF FF FF FF 04 7D 47 07 01 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00
SAPP: 1E 01 08 48 FF FF FF FF 04 7D 48 07 01 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00
SAPP: 1E 01 08 49 FF FF FF FF 04 7D 49 07 01 00 00 00 00 00 00 00 00
00 00 00 00 00 00 00 00 00 00 00
The code for Counter.nc <http://counter.nc/> :
module Counter {
provides {
interface StdControl;
}
uses {
interface Timer;
interface IntOutput;
}
}
implementation {
int state;
uint8_t num;
command result_t StdControl.init()
{
state = 1;
atomic num = 0;
return SUCCESS;
}
command result_t StdControl.start()
{
return call Timer.start (TIMER_REPEAT, 1000);
}
command result_t StdControl.stop()
{
return call Timer.stop();
}
task void intOutput()
{
if (call IntOutput.output(state))
state++;
}
event result_t Timer.fired()
{
post intOutput();
#if 0
if (call IntOutput.output(state))
state++;
dbg(DBG_TEMP|DBG_USR1, "Counter: Value is %i\n", (int)state);
#endif
return SUCCESS;
}
event result_t IntOutput.outputComplete(result_t success)
{
uint8_t temp;
if(success == 0) state --;
atomic temp = num;
if (temp < 3)
{
post intOutput();
atomic num++;
}
else
{
atomic num = 0;
}
return SUCCESS;
}
}
Regards,
Harish
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