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

[Andreas Koepke]

>>
>> 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 ;-)

>> 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).

Best, Andreas