[Tinyos-devel] lost packets from PC to the mote

[Razvan Musaloiu-E.]

Hi!

On Mon, 21 Apr 2008, Andreas Koepke wrote:

>>> 
>>> Correct, now for a little math: At 115200 Bit/s the uC has 86us to process 
>>> each byte.
>> 
>> 115200 bits = 14400 bytes and 1/14400 is about 7e-05. So the MCU has around 
>> 70us to deal with each byte.
>
> Don't forget the start and the stop bit ;-)

Right. :P

>>> If both directions are used, this drops to 43us. Scheduling a timer takes 
>>> about this much in T2. So if the node happens to do something else than 
>>> mere byte crunching, packets may be lost.
>> 
>> This situation should be indicated by some overflow register from MSP420, 
>> right?
>
> The uC can signal this, but the default configuration in T2 prevents this. So 
> to check this, change the default configuration for the serial interface and 
> modify the interrupt handler (you have to check the flags immediately before 
> reading the byte).

Thanks for suggestion. I'll give it a try after IPSN. :D

All the best!
Razvan ME