> If you look at system/LedsC.nc and you will see it does more than just
> call TOSH_xxx.
>
I just did that and the _more_ is setting a bit in a local variable
(which is actually unnecessary because one _could_ just read back the
value of the pin), but this should amount to about 3 instructions
plus the function call overhead. Assuming that SET and CLR are single
instructions I count maybe 6 @ 1us... I guess I should go look at the
generated ASM and see what's using the other 2/3 of the time...
MS
Cory Sharp wrote:
On 11/15/06, *Chong Hui Kim* <[EMAIL PROTECTED]
<mailto:[EMAIL PROTECTED]>> wrote:
Dear all,
Now, I have tried to measure the execution time of several modules.
To measure exeuction time, I used the logic analyzer.
But, I found some strange things.
1. When I called Leds interface sequentially as below, I found that
it took a time about 20us.
call Leds.redOn();
call Leds.redOff();
But I found that it took a time about 2us when I called TOSH_SET
and TOSh_CLR.
TOSH_SET_RED_PIN();
TOSH_CLR_RED_PIN();
In my thought, it took much time since Leds interface used
operating system.
Why does two methods task a different elapsed time?
If you look at system/LedsC.nc and you will see it does more than just
call TOSH_xxx.
2. When I call send ZigBee TX in OscilloscopeRF application, I found
that it took a time about 4-8ms between call Send and event sendDone.
There are two questions. 1) Why is the difference of transmission
time large? 2) I think that it takes a long time to transmit packet
about 4ms. If I want to synchronize two modules, I think that I must
send packet for synchronization with short transmission time. Why is
transmission time large?
The delay is a combination of the backoff timer and clear channel
assessment.
Cory
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