On 11/15/06, Michael Schippling <[EMAIL PROTECTED]> wrote:
> 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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