Hi Hugo,
Your guess is right. I read one axis, then wait readDone() to start another
axis. Your explanation let me understand what caused this problem. However,
I still cannot understand how to use accelStream. I list my old methods as
follows. Please help find how to solve the problem.
I created a DemoSensorXC and a DemoSensorYC, which look like:
generic configuration DemoSensorXC() {
provides interface Read<uint16_t>;
}
implementation {
components new AccelXC() as Sensor;
Read = Sensor;
}
In the application code, it look like:
module GetAccelC
{
uses {
interface Read<uint16_t> as ReadX;
interface Read<uint16_t> as ReadY;
...
}
}
implementation
{
//start to read X axis
event void Timer.fired() {
if (call ReadX.read() != SUCCESS)
report_problem();
}
//start to read Y axis after X is done
event void ReadX.readDone(error_t result, uint16_t data)
{
if (result != SUCCESS)
{
data = 0xffff;
report_problem();
}
local.readings[0] = data;
//start to read Y axial acceleration
if (call ReadY.read() != SUCCESS)
report_problem();
}
//send message out when Y is done
event void ReadY.readDone(error_t result, uint16_t data)
{
if (result != SUCCESS)
{
data = 0xffff;
report_problem();
}
local.readings[1] = data;
//send
if (!sendbusy && sizeof local <= call AMSend.maxPayloadLength())
{
memcpy(call AMSend.getPayload(&sendbuf), &local, sizeof local);
if (call AMSend.send(AM_BROADCAST_ADDR, &sendbuf, sizeof local)
== SUCCESS)
sendbusy = TRUE;
}
if (!sendbusy)
report_problem();
/* Part 2 of cheap "time sync": increment our count if we didn't
jump ahead. */
if (!suppress_count_change)
local.count++;
suppress_count_change = FALSE;
}
}
I think the key is the AccelConfigP.nc is used only once, but I still don't
know how to realize it. Is that right?
Regards,
Fangming
On 5/12/07, Hugo Sousa <[EMAIL PROTECTED]> wrote:
We need more information about your application, but I'm guessing you are
reading one axis, and when you get the readDone() you read the other axis,
right?
The accelerometer sensor has a warmup time of 17 ms (check AccelP.nc),
that means that every time you do a Read.read() it takes 17 ms to turn it
on and receive one reading. So the time for two readings (one X axis read
and one Y axis read) can be 34ms and that value comes allows 30Hz sampling
frequency,
Try using the accelStream components to get that frequency sampling.
Cheers
Hugo
On 5/12/07, Fangming Zhang < [EMAIL PROTECTED]> wrote:
> Hi everyone,
>
> My hardwares are MIB520, MTS310, and MICAZ. The transmitting rate of
> MIB520 is 57.4Kbps, and that of MICAZ is 250Kbps. The platform is
> Tinyos2.0. My objective is getting sample frequency of 64Hz when I only
> need data of accelerometer data, X and Y axis. However, it shows we can only
> obtain about 31Hz in my test expriment. Does this limited my TinyOs2.0?
> Or, is there any methods could improve this result?
>
> Regards,
> Fangming
>
> _______________________________________________
> Tinyos-help mailing list
> Tinyos-help@Millennium.Berkeley.EDU
> https://mail.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
>
>
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