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* [Xenomai-help] RTDM rs232 strange behavior
@ 2010-06-05  2:22 Everett Wang
  2010-06-07  8:05 ` Wolfgang Grandegger
  2010-06-09  6:19 ` Wolfgang Grandegger
  0 siblings, 2 replies; 7+ messages in thread
From: Everett Wang @ 2010-06-05  2:22 UTC (permalink / raw)
  To: xenomai

Hi All,

I am playing around with xenomai and RTDM serial driver on a
1.7Ghz Pentium-M machine running xenomai 2.5.3. The example cross-link
produced this result:

main : starting read-task
 Nr |   write->irq    |    irq->read    |   write->read   |
-----------------------------------------------------------
  0 |          118948 |          614135 |          733083
  1 |          115598 |          614281 |          729879
  2 |          108917 |          614982 |          723899
  3 |          106101 |          616560 |          722661
  4 |          113457 |          614971 |          728428
  5 |          110358 |          614265 |          724623
  6 |          106499 |          614406 |          720905
  7 |          110363 |          615015 |          725378
  8 |          115478 |          614840 |          730318
  9 |          110766 |          614168 |          724934
 10 |          108986 |          616435 |          725421
 11 |          108030 |          614299 |          722329
 12 |          109369 |          614420 |          723789
 13 |          105862 |          614456 |          720318
 14 |          110428 |          616301 |          726729

Is 0.7 millisecond between write and read a reasonable number?


I then changed the example a little: I let write task only
write 4 characters and instruct read task to read 10 characters.
I thought the read task will tell me when that only 4 characters
is read. But to my surprise, it waited until write-task
filled all 10 characters before finish reading. How can I
change the code to just do the read to whatever charaters
are avaliable without waiting to fill all the characters I
asked for? I will use this capability to read a GPS. It's
output length is unknow before reading.

Most GPS can also produce a precisive time pulse when data
is ready. Is it be possible to connect this to a pin in rs232 (CTS, for example)
to triger a IRQ so the data can be read in a timely manner?

Many thanks in advance.

Everett


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [Xenomai-help] RTDM rs232 strange behavior
  2010-06-05  2:22 [Xenomai-help] RTDM rs232 strange behavior Everett Wang
@ 2010-06-07  8:05 ` Wolfgang Grandegger
  2010-06-07 12:07   ` Everett Wang
  2010-06-09  6:19 ` Wolfgang Grandegger
  1 sibling, 1 reply; 7+ messages in thread
From: Wolfgang Grandegger @ 2010-06-07  8:05 UTC (permalink / raw)
  To: Everett Wang; +Cc: xenomai

On 06/05/2010 04:22 AM, Everett Wang wrote:
> Hi All,
> 
> I am playing around with xenomai and RTDM serial driver on a
> 1.7Ghz Pentium-M machine running xenomai 2.5.3. The example cross-link
> produced this result:
> 
> main : starting read-task
>  Nr |   write->irq    |    irq->read    |   write->read   |
> -----------------------------------------------------------
>   0 |          118948 |          614135 |          733083
>   1 |          115598 |          614281 |          729879
>   2 |          108917 |          614982 |          723899
>   3 |          106101 |          616560 |          722661
>   4 |          113457 |          614971 |          728428
>   5 |          110358 |          614265 |          724623
>   6 |          106499 |          614406 |          720905
>   7 |          110363 |          615015 |          725378
>   8 |          115478 |          614840 |          730318
>   9 |          110766 |          614168 |          724934
>  10 |          108986 |          616435 |          725421
>  11 |          108030 |          614299 |          722329
>  12 |          109369 |          614420 |          723789
>  13 |          105862 |          614456 |          720318
>  14 |          110428 |          616301 |          726729
> 
> Is 0.7 millisecond between write and read a reasonable number?

No, at least not for a baudrate of 115200. Does the "latency" test
report reasonable latency figures? And how did you load xeno_16550A.ko?

> I then changed the example a little: I let write task only
> write 4 characters and instruct read task to read 10 characters.
> I thought the read task will tell me when that only 4 characters
> is read. But to my surprise, it waited until write-task
> filled all 10 characters before finish reading. How can I
> change the code to just do the read to whatever charaters
> are avaliable without waiting to fill all the characters I
> asked for? I will use this capability to read a GPS. It's
> output length is unknow before reading.

Setting the config rx timeout to RTSER_TIMEOUT_NONE should help.

> Most GPS can also produce a precisive time pulse when data
> is ready. Is it be possible to connect this to a pin in rs232 (CTS, for example)
> to triger a IRQ so the data can be read in a timely manner?

That depends on the signals, I can imagine. I'm not a hardware guy but I
know that many GPS receiver come with a read-to-use RS232 interface.

Wolfgang.


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [Xenomai-help] RTDM rs232 strange behavior
  2010-06-07  8:05 ` Wolfgang Grandegger
@ 2010-06-07 12:07   ` Everett Wang
  2010-06-07 13:17     ` Wolfgang Grandegger
  0 siblings, 1 reply; 7+ messages in thread
From: Everett Wang @ 2010-06-07 12:07 UTC (permalink / raw)
  To: Wolfgang Grandegger; +Cc: xenomai

I am so glad that Wolfgang is able to help giving suggestions. Thanks
a lot. That is very useful for new users. :-)

On Mon, Jun 7, 2010 at 4:05 PM, Wolfgang Grandegger <wg@domain.hid> wrote:
> On 06/05/2010 04:22 AM, Everett Wang wrote:
>> Hi All,
>>
>> I am playing around with xenomai and RTDM serial driver on a
>> 1.7Ghz Pentium-M machine running xenomai 2.5.3. The example cross-link
>> produced this result:
>>
>> main : starting read-task
>>  Nr |   write->irq    |    irq->read    |   write->read   |
>> -----------------------------------------------------------
>>   0 |          118948 |          614135 |          733083
>>   1 |          115598 |          614281 |          729879
>>   2 |          108917 |          614982 |          723899
>>   3 |          106101 |          616560 |          722661
>>   4 |          113457 |          614971 |          728428
>>   5 |          110358 |          614265 |          724623
>>   6 |          106499 |          614406 |          720905
>>   7 |          110363 |          615015 |          725378
>>   8 |          115478 |          614840 |          730318
>>   9 |          110766 |          614168 |          724934
>>  10 |          108986 |          616435 |          725421
>>  11 |          108030 |          614299 |          722329
>>  12 |          109369 |          614420 |          723789
>>  13 |          105862 |          614456 |          720318
>>  14 |          110428 |          616301 |          726729
>>
>> Is 0.7 millisecond between write and read a reasonable number?
>
> No, at least not for a baudrate of 115200. Does the "latency" test
> report reasonable latency figures? And how did you load xeno_16550A.ko?
>
The latency test seems very reasonable:
4 microseconds when I try to open several browers at the
same time:

mini:/usr/xenomai/share/xenomai/testsuite/klatency# ./run
*
*
* Type ^C to stop this application.
*
*
== Sampling period: 100 us
== Test mode: in-kernel periodic task
== All results in microseconds
warming up...
RTT|  00:00:01  (in-kernel periodic task, 100 us period, priority 99)
RTH|-----lat min|-----lat avg|-----lat max|-overrun|----lat best|---lat worst
RTD|      -0.722|      -0.618|       0.755|       0|      -0.722|       0.755
RTD|      -0.721|      -0.616|       0.803|       0|      -0.722|       0.803
RTD|      -0.708|      -0.616|       0.876|       0|      -0.722|       0.876
RTD|      -0.722|      -0.616|       0.854|       0|      -0.722|       0.876
RTD|      -0.708|      -0.617|       0.954|       0|      -0.722|       0.954
RTD|      -0.709|      -0.615|       0.682|       0|      -0.722|       0.954
RTD|      -0.724|      -0.595|       0.918|       0|      -0.724|       0.954
RTD|      -0.728|      -0.477|       2.785|       0|      -0.728|       2.785
RTD|      -0.725|      -0.526|       2.721|       0|      -0.728|       2.785
RTD|      -0.729|      -0.512|       2.609|       0|      -0.729|       2.785
RTD|      -0.726|      -0.485|       4.483|       0|      -0.729|       4.483
RTD|      -0.726|      -0.479|       4.142|       0|      -0.729|       4.483
RTD|      -0.723|      -0.542|       2.735|       0|      -0.729|       4.483
RTD|      -0.728|      -0.580|       1.896|       0|      -0.729|       4.483
RTD|      -0.728|      -0.540|       2.196|       0|      -0.729|       4.483
RTD|      -0.726|      -0.566|       1.831|       0|      -0.729|       4.483
RTD|      -0.711|      -0.607|       1.768|       0|      -0.729|       4.483
RTD|      -0.712|      -0.591|       1.050|       0|      -0.729|       4.483
RTD|      -0.721|      -0.615|       1.116|       0|      -0.729|       4.483
RTD|      -0.712|      -0.612|       0.694|       0|      -0.729|       4.483
RTD|      -0.721|      -0.614|       0.782|       0|      -0.729|       4.483
^CRTT|  00:00:22  (in-kernel periodic task, 100 us period, priority 99)
RTH|-----lat min|-----lat avg|-----lat max|-overrun|----lat best|---lat worst
RTD|      -0.724|      -0.610|       1.213|       0|      -0.729|       4.483
---|------------|------------|------------|--------|-------------------------
RTS|      -0.729|      -0.554|       4.483|       0|    00:00:24/00:00:24
mini:/usr/xenomai/share/xenomai/testsuite/klatency#

The user space latency is also reasonable at 10 microseconds:
mini:/usr/xenomai/share/xenomai/testsuite/latency# ./run
*
*
* Type ^C to stop this application.
*
*
== Sampling period: 100 us
== Test mode: periodic user-mode task
== All results in microseconds
warming up...
RTT|  00:00:01  (periodic user-mode task, 100 us period, priority 99)
RTH|----lat min|----lat avg|----lat max|-overrun|---msw|---lat best|--lat worst
RTD|      0.245|      0.391|      2.736|       0|     0|      0.245|      2.736
RTD|      0.132|      0.663|      7.012|       0|     0|      0.132|      7.012
RTD|      0.248|      0.871|      6.954|       0|     0|      0.132|      7.012
RTD|      0.245|      0.650|      5.741|       0|     0|      0.132|      7.012
RTD|      0.213|      1.009|     10.657|       0|     0|      0.132|     10.657
RTD|      0.247|      0.902|      8.936|       0|     0|      0.132|     10.657
RTD|      0.177|      0.776|      6.978|       0|     0|      0.132|     10.657
RTD|      0.246|      0.735|      7.571|       0|     0|      0.132|     10.657
RTD|      0.245|      0.918|      8.821|       0|     0|      0.132|     10.657
RTD|      0.127|      0.387|      3.423|       0|     0|      0.127|     10.657
RTD|      0.138|      0.429|      2.977|       0|     0|      0.127|     10.657
RTD|      0.096|      0.357|      3.100|       0|     0|      0.096|     10.657
RTD|      0.133|      0.357|      3.019|       0|     0|      0.096|     10.657
RTD|      0.132|      0.356|      2.246|       0|     0|      0.096|     10.657
RTD|      0.140|      0.382|      5.711|       0|     0|      0.096|     10.657
RTD|      0.131|      0.361|      2.041|       0|     0|      0.096|     10.657
^C---|-----------|-----------|-----------|--------|------|-------------------------
RTS|      0.096|      0.596|     10.657|       0|     0|    00:00:16/00:00:16
mini:/usr/xenomai/share/xenomai/testsuite/latency#

I load driver using this before running cross-link examples:

setserial /dev/ttyS0 uart none
setserial /dev/ttyS1 uart none
insmod /lib/modules/2.6.32.11-xeno/kernel/drivers/xenomai/serial/xeno_16550A.ko
io=0x3f8,0x2f8 irq=4,3 tx_fifo=10,20 start_index=0



>> I then changed the example a little: I let write task only
>> write 4 characters and instruct read task to read 10 characters.
>> I thought the read task will tell me when that only 4 characters
>> is read. But to my surprise, it waited until write-task
>> filled all 10 characters before finish reading. How can I
>> change the code to just do the read to whatever charaters
>> are avaliable without waiting to fill all the characters I
>> asked for? I will use this capability to read a GPS. It's
>> output length is unknow before reading.
>
> Setting the config rx timeout to RTSER_TIMEOUT_NONE should help.
>
Thanks for the suggestion, I will try that.

>> Most GPS can also produce a precisive time pulse when data
>> is ready. Is it be possible to connect this to a pin in rs232 (CTS, for example)
>> to triger a IRQ so the data can be read in a timely manner?
>
> That depends on the signals, I can imagine. I'm not a hardware guy but I
> know that many GPS receiver come with a read-to-use RS232 interface.
>
> Wolfgang.
>
Yes, you are right. My GPS has a rs232 port and I am trying
to use it. The GPS just dump out some information to the
rs232 port every 0.1 second. I am just trying to get the information
in a timely fashion. I thought that the extra time
pulse from the GPS can help.

Thanks a lot again for your help.

Everett


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [Xenomai-help] RTDM rs232 strange behavior
  2010-06-07 12:07   ` Everett Wang
@ 2010-06-07 13:17     ` Wolfgang Grandegger
  2010-06-08  1:32       ` Everett Wang
  0 siblings, 1 reply; 7+ messages in thread
From: Wolfgang Grandegger @ 2010-06-07 13:17 UTC (permalink / raw)
  To: Everett Wang; +Cc: xenomai

On 06/07/2010 02:07 PM, Everett Wang wrote:
> I am so glad that Wolfgang is able to help giving suggestions. Thanks
> a lot. That is very useful for new users. :-)
> 
> On Mon, Jun 7, 2010 at 4:05 PM, Wolfgang Grandegger <wg@domain.hid> wrote:
>> On 06/05/2010 04:22 AM, Everett Wang wrote:
>>> Hi All,
>>>
>>> I am playing around with xenomai and RTDM serial driver on a
>>> 1.7Ghz Pentium-M machine running xenomai 2.5.3. The example cross-link
>>> produced this result:
>>>
>>> main : starting read-task
>>>  Nr |   write->irq    |    irq->read    |   write->read   |
>>> -----------------------------------------------------------
>>>   0 |          118948 |          614135 |          733083
>>>   1 |          115598 |          614281 |          729879
>>>   2 |          108917 |          614982 |          723899
>>>   3 |          106101 |          616560 |          722661
>>>   4 |          113457 |          614971 |          728428
>>>   5 |          110358 |          614265 |          724623
>>>   6 |          106499 |          614406 |          720905
>>>   7 |          110363 |          615015 |          725378
>>>   8 |          115478 |          614840 |          730318
>>>   9 |          110766 |          614168 |          724934
>>>  10 |          108986 |          616435 |          725421
>>>  11 |          108030 |          614299 |          722329
>>>  12 |          109369 |          614420 |          723789
>>>  13 |          105862 |          614456 |          720318
>>>  14 |          110428 |          616301 |          726729
>>>
>>> Is 0.7 millisecond between write and read a reasonable number?
>>
>> No, at least not for a baudrate of 115200. Does the "latency" test
>> report reasonable latency figures? And how did you load xeno_16550A.ko?
>>
> The latency test seems very reasonable:
> 4 microseconds when I try to open several browers at the
> same time:
> 
> mini:/usr/xenomai/share/xenomai/testsuite/klatency# ./run
> *
> *
> * Type ^C to stop this application.
> *
> *
> == Sampling period: 100 us
> == Test mode: in-kernel periodic task
> == All results in microseconds
> warming up...
> RTT|  00:00:01  (in-kernel periodic task, 100 us period, priority 99)
> RTH|-----lat min|-----lat avg|-----lat max|-overrun|----lat best|---lat worst
> RTD|      -0.722|      -0.618|       0.755|       0|      -0.722|       0.755
> RTD|      -0.721|      -0.616|       0.803|       0|      -0.722|       0.803
> RTD|      -0.708|      -0.616|       0.876|       0|      -0.722|       0.876
> RTD|      -0.722|      -0.616|       0.854|       0|      -0.722|       0.876
> RTD|      -0.708|      -0.617|       0.954|       0|      -0.722|       0.954
> RTD|      -0.709|      -0.615|       0.682|       0|      -0.722|       0.954
> RTD|      -0.724|      -0.595|       0.918|       0|      -0.724|       0.954
> RTD|      -0.728|      -0.477|       2.785|       0|      -0.728|       2.785
> RTD|      -0.725|      -0.526|       2.721|       0|      -0.728|       2.785
> RTD|      -0.729|      -0.512|       2.609|       0|      -0.729|       2.785
> RTD|      -0.726|      -0.485|       4.483|       0|      -0.729|       4.483
> RTD|      -0.726|      -0.479|       4.142|       0|      -0.729|       4.483
> RTD|      -0.723|      -0.542|       2.735|       0|      -0.729|       4.483
> RTD|      -0.728|      -0.580|       1.896|       0|      -0.729|       4.483
> RTD|      -0.728|      -0.540|       2.196|       0|      -0.729|       4.483
> RTD|      -0.726|      -0.566|       1.831|       0|      -0.729|       4.483
> RTD|      -0.711|      -0.607|       1.768|       0|      -0.729|       4.483
> RTD|      -0.712|      -0.591|       1.050|       0|      -0.729|       4.483
> RTD|      -0.721|      -0.615|       1.116|       0|      -0.729|       4.483
> RTD|      -0.712|      -0.612|       0.694|       0|      -0.729|       4.483
> RTD|      -0.721|      -0.614|       0.782|       0|      -0.729|       4.483
> ^CRTT|  00:00:22  (in-kernel periodic task, 100 us period, priority 99)
> RTH|-----lat min|-----lat avg|-----lat max|-overrun|----lat best|---lat worst
> RTD|      -0.724|      -0.610|       1.213|       0|      -0.729|       4.483
> ---|------------|------------|------------|--------|-------------------------
> RTS|      -0.729|      -0.554|       4.483|       0|    00:00:24/00:00:24
> mini:/usr/xenomai/share/xenomai/testsuite/klatency#
> 
> The user space latency is also reasonable at 10 microseconds:
> mini:/usr/xenomai/share/xenomai/testsuite/latency# ./run
> *
> *
> * Type ^C to stop this application.
> *
> *
> == Sampling period: 100 us
> == Test mode: periodic user-mode task
> == All results in microseconds
> warming up...
> RTT|  00:00:01  (periodic user-mode task, 100 us period, priority 99)
> RTH|----lat min|----lat avg|----lat max|-overrun|---msw|---lat best|--lat worst
> RTD|      0.245|      0.391|      2.736|       0|     0|      0.245|      2.736
> RTD|      0.132|      0.663|      7.012|       0|     0|      0.132|      7.012
> RTD|      0.248|      0.871|      6.954|       0|     0|      0.132|      7.012
> RTD|      0.245|      0.650|      5.741|       0|     0|      0.132|      7.012
> RTD|      0.213|      1.009|     10.657|       0|     0|      0.132|     10.657
> RTD|      0.247|      0.902|      8.936|       0|     0|      0.132|     10.657
> RTD|      0.177|      0.776|      6.978|       0|     0|      0.132|     10.657
> RTD|      0.246|      0.735|      7.571|       0|     0|      0.132|     10.657
> RTD|      0.245|      0.918|      8.821|       0|     0|      0.132|     10.657
> RTD|      0.127|      0.387|      3.423|       0|     0|      0.127|     10.657
> RTD|      0.138|      0.429|      2.977|       0|     0|      0.127|     10.657
> RTD|      0.096|      0.357|      3.100|       0|     0|      0.096|     10.657
> RTD|      0.133|      0.357|      3.019|       0|     0|      0.096|     10.657
> RTD|      0.132|      0.356|      2.246|       0|     0|      0.096|     10.657
> RTD|      0.140|      0.382|      5.711|       0|     0|      0.096|     10.657
> RTD|      0.131|      0.361|      2.041|       0|     0|      0.096|     10.657
> ^C---|-----------|-----------|-----------|--------|------|-------------------------
> RTS|      0.096|      0.596|     10.657|       0|     0|    00:00:16/00:00:16
> mini:/usr/xenomai/share/xenomai/testsuite/latency#
> 
> I load driver using this before running cross-link examples:
> 
> setserial /dev/ttyS0 uart none
> setserial /dev/ttyS1 uart none
> insmod /lib/modules/2.6.32.11-xeno/kernel/drivers/xenomai/serial/xeno_16550A.ko
> io=0x3f8,0x2f8 irq=4,3 tx_fifo=10,20 start_index=0

Are the interrupts shared with some other devices. What does
/proc/interrupt show when you run the test? Also, the default tx_fifo
should be fine. And what does "setserial -G /dev/ttyS0" list before you
disable the device (with "uart none").

>>> I then changed the example a little: I let write task only
>>> write 4 characters and instruct read task to read 10 characters.
>>> I thought the read task will tell me when that only 4 characters
>>> is read. But to my surprise, it waited until write-task
>>> filled all 10 characters before finish reading. How can I
>>> change the code to just do the read to whatever charaters
>>> are avaliable without waiting to fill all the characters I
>>> asked for? I will use this capability to read a GPS. It's
>>> output length is unknow before reading.
>>
>> Setting the config rx timeout to RTSER_TIMEOUT_NONE should help.
>>
> Thanks for the suggestion, I will try that.
> 
>>> Most GPS can also produce a precisive time pulse when data
>>> is ready. Is it be possible to connect this to a pin in rs232 (CTS, for example)
>>> to triger a IRQ so the data can be read in a timely manner?
>>
>> That depends on the signals, I can imagine. I'm not a hardware guy but I
>> know that many GPS receiver come with a read-to-use RS232 interface.
>>
>> Wolfgang.
>>
> Yes, you are right. My GPS has a rs232 port and I am trying
> to use it. The GPS just dump out some information to the
> rs232 port every 0.1 second. I am just trying to get the information
> in a timely fashion. I thought that the extra time
> pulse from the GPS can help.

Just reading out the received data should be fine. They will generate an
interrupt anyway.

Wolfgang.


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [Xenomai-help] RTDM rs232 strange behavior
  2010-06-07 13:17     ` Wolfgang Grandegger
@ 2010-06-08  1:32       ` Everett Wang
  2010-06-08  2:46         ` Everett Wang
  0 siblings, 1 reply; 7+ messages in thread
From: Everett Wang @ 2010-06-08  1:32 UTC (permalink / raw)
  To: Wolfgang Grandegger; +Cc: xenomai

Hi Wolfgang,

Thanks for your quick email. :-)

On Mon, Jun 7, 2010 at 9:17 PM, Wolfgang Grandegger <wg@domain.hid> wrote:
> On 06/07/2010 02:07 PM, Everett Wang wrote:
>> I am so glad that Wolfgang is able to help giving suggestions. Thanks
>> a lot. That is very useful for new users. :-)
>>
>> On Mon, Jun 7, 2010 at 4:05 PM, Wolfgang Grandegger <wg@domain.hid> wrote:
>>> On 06/05/2010 04:22 AM, Everett Wang wrote:
>>>> Hi All,
>>>>
>>>> I am playing around with xenomai and RTDM serial driver on a
>>>> 1.7Ghz Pentium-M machine running xenomai 2.5.3. The example cross-link
>>>> produced this result:
>>>>
>>>> main : starting read-task
>>>>  Nr |   write->irq    |    irq->read    |   write->read   |
>>>> -----------------------------------------------------------
>>>>   0 |          118948 |          614135 |          733083
>>>>   1 |          115598 |          614281 |          729879
>>>>   2 |          108917 |          614982 |          723899
>>>>   3 |          106101 |          616560 |          722661
>>>>   4 |          113457 |          614971 |          728428
>>>>   5 |          110358 |          614265 |          724623
>>>>   6 |          106499 |          614406 |          720905
>>>>   7 |          110363 |          615015 |          725378
>>>>   8 |          115478 |          614840 |          730318
>>>>   9 |          110766 |          614168 |          724934
>>>>  10 |          108986 |          616435 |          725421
>>>>  11 |          108030 |          614299 |          722329
>>>>  12 |          109369 |          614420 |          723789
>>>>  13 |          105862 |          614456 |          720318
>>>>  14 |          110428 |          616301 |          726729
>>>>
>>>> Is 0.7 millisecond between write and read a reasonable number?
>>>
>>> No, at least not for a baudrate of 115200. Does the "latency" test
>>> report reasonable latency figures? And how did you load xeno_16550A.ko?
>>>
>> The latency test seems very reasonable:
>> 4 microseconds when I try to open several browers at the
>> same time:
>>
>> mini:/usr/xenomai/share/xenomai/testsuite/klatency# ./run
>> *
>> *
>> * Type ^C to stop this application.
>> *
>> *
>> == Sampling period: 100 us
>> == Test mode: in-kernel periodic task
>> == All results in microseconds
>> warming up...
>> RTT|  00:00:01  (in-kernel periodic task, 100 us period, priority 99)
>> RTH|-----lat min|-----lat avg|-----lat max|-overrun|----lat best|---lat worst
>> RTD|      -0.722|      -0.618|       0.755|       0|      -0.722|       0.755
>> RTD|      -0.721|      -0.616|       0.803|       0|      -0.722|       0.803
>> RTD|      -0.708|      -0.616|       0.876|       0|      -0.722|       0.876
>> RTD|      -0.722|      -0.616|       0.854|       0|      -0.722|       0.876
>> RTD|      -0.708|      -0.617|       0.954|       0|      -0.722|       0.954
>> RTD|      -0.709|      -0.615|       0.682|       0|      -0.722|       0.954
>> RTD|      -0.724|      -0.595|       0.918|       0|      -0.724|       0.954
>> RTD|      -0.728|      -0.477|       2.785|       0|      -0.728|       2.785
>> RTD|      -0.725|      -0.526|       2.721|       0|      -0.728|       2.785
>> RTD|      -0.729|      -0.512|       2.609|       0|      -0.729|       2.785
>> RTD|      -0.726|      -0.485|       4.483|       0|      -0.729|       4.483
>> RTD|      -0.726|      -0.479|       4.142|       0|      -0.729|       4.483
>> RTD|      -0.723|      -0.542|       2.735|       0|      -0.729|       4.483
>> RTD|      -0.728|      -0.580|       1.896|       0|      -0.729|       4.483
>> RTD|      -0.728|      -0.540|       2.196|       0|      -0.729|       4.483
>> RTD|      -0.726|      -0.566|       1.831|       0|      -0.729|       4.483
>> RTD|      -0.711|      -0.607|       1.768|       0|      -0.729|       4.483
>> RTD|      -0.712|      -0.591|       1.050|       0|      -0.729|       4.483
>> RTD|      -0.721|      -0.615|       1.116|       0|      -0.729|       4.483
>> RTD|      -0.712|      -0.612|       0.694|       0|      -0.729|       4.483
>> RTD|      -0.721|      -0.614|       0.782|       0|      -0.729|       4.483
>> ^CRTT|  00:00:22  (in-kernel periodic task, 100 us period, priority 99)
>> RTH|-----lat min|-----lat avg|-----lat max|-overrun|----lat best|---lat worst
>> RTD|      -0.724|      -0.610|       1.213|       0|      -0.729|       4.483
>> ---|------------|------------|------------|--------|-------------------------
>> RTS|      -0.729|      -0.554|       4.483|       0|    00:00:24/00:00:24
>> mini:/usr/xenomai/share/xenomai/testsuite/klatency#
>>
>> The user space latency is also reasonable at 10 microseconds:
>> mini:/usr/xenomai/share/xenomai/testsuite/latency# ./run
>> *
>> *
>> * Type ^C to stop this application.
>> *
>> *
>> == Sampling period: 100 us
>> == Test mode: periodic user-mode task
>> == All results in microseconds
>> warming up...
>> RTT|  00:00:01  (periodic user-mode task, 100 us period, priority 99)
>> RTH|----lat min|----lat avg|----lat max|-overrun|---msw|---lat best|--lat worst
>> RTD|      0.245|      0.391|      2.736|       0|     0|      0.245|      2.736
>> RTD|      0.132|      0.663|      7.012|       0|     0|      0.132|      7.012
>> RTD|      0.248|      0.871|      6.954|       0|     0|      0.132|      7.012
>> RTD|      0.245|      0.650|      5.741|       0|     0|      0.132|      7.012
>> RTD|      0.213|      1.009|     10.657|       0|     0|      0.132|     10.657
>> RTD|      0.247|      0.902|      8.936|       0|     0|      0.132|     10.657
>> RTD|      0.177|      0.776|      6.978|       0|     0|      0.132|     10.657
>> RTD|      0.246|      0.735|      7.571|       0|     0|      0.132|     10.657
>> RTD|      0.245|      0.918|      8.821|       0|     0|      0.132|     10.657
>> RTD|      0.127|      0.387|      3.423|       0|     0|      0.127|     10.657
>> RTD|      0.138|      0.429|      2.977|       0|     0|      0.127|     10.657
>> RTD|      0.096|      0.357|      3.100|       0|     0|      0.096|     10.657
>> RTD|      0.133|      0.357|      3.019|       0|     0|      0.096|     10.657
>> RTD|      0.132|      0.356|      2.246|       0|     0|      0.096|     10.657
>> RTD|      0.140|      0.382|      5.711|       0|     0|      0.096|     10.657
>> RTD|      0.131|      0.361|      2.041|       0|     0|      0.096|     10.657
>> ^C---|-----------|-----------|-----------|--------|------|-------------------------
>> RTS|      0.096|      0.596|     10.657|       0|     0|    00:00:16/00:00:16
>> mini:/usr/xenomai/share/xenomai/testsuite/latency#
>>
>> I load driver using this before running cross-link examples:
>>
>> setserial /dev/ttyS0 uart none
>> setserial /dev/ttyS1 uart none
>> insmod /lib/modules/2.6.32.11-xeno/kernel/drivers/xenomai/serial/xeno_16550A.ko
>> io=0x3f8,0x2f8 irq=4,3 tx_fifo=10,20 start_index=0
>
> Are the interrupts shared with some other devices. What does
> /proc/interrupt show when you run the test? Also, the default tx_fifo
> should be fine. And what does "setserial -G /dev/ttyS0" list before you
> disable the device (with "uart none").
>

I look at the bios setting. All irqs are set automatically. Window
setup indicated no conflict of IRQs. But dmesg has this:

 [    0.356143] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
[    0.356143] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
[    0.356143] serial8250: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A
[    0.359109] 00:07: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
[    0.359263] 00:08: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A

I guess the IRQ is shared with something else. But I can't finger our
what else is using IRQ 3 and 4. The computer has only two serial
ports.

setserial -G has this:

#  setserial -G /dev/ttyS0
/dev/ttyS0 uart 16550A port 0x03f8 irq 4 baud_base 115200 spd_normal skip_test
# setserial -G /dev/ttyS1
/dev/ttyS1 uart 16550A port 0x02f8 irq 3 baud_base 115200 spd_normal skip_test

Now I load xeno_16550A.ko with default fifo.
I also looked at the /proc/interrupt file
during running of the cross-link
everett@domain.hid$ cat interrupts
           CPU0
  0:      18169   IO-APIC-edge      timer
  1:       1492   IO-APIC-edge      i8042
  3:         10   IO-APIC-edge
  4:          9   IO-APIC-edge
  7:          0   IO-APIC-edge      parport0
  8:          2   IO-APIC-edge      rtc0
  9:          0   IO-APIC-fasteoi   acpi
 10:          0   IO-APIC-edge      MPU401 UART
 14:       7835   IO-APIC-edge      ide0
 15:       6662   IO-APIC-edge      ide1
 16:       9665   IO-APIC-fasteoi   uhci_hcd:usb1, i915@domain.hid
 17:          1   IO-APIC-fasteoi   Intel 82801DB-ICH4
 18:      28708   IO-APIC-fasteoi   uhci_hcd:usb4, ipw2200
 19:          0   IO-APIC-fasteoi   uhci_hcd:usb3
 20:       3660   IO-APIC-fasteoi   eth0
 23:          2   IO-APIC-fasteoi   ehci_hcd:usb2
NMI:          0   Non-maskable interrupts
LOC:      72987   Local timer interrupts
SPU:          0   Spurious interrupts
PMI:          0   Performance monitoring interrupts
PND:          0   Performance pending work
TRM:          0   Thermal event interrupts
THR:          0   Threshold APIC interrupts
MCE:          0   Machine check exceptions
MCP:          3   Machine check polls
ERR:          0
MIS:          0

I can see IRQ 1, which is used by i8042, as well as local time
interrupt are increasing. But not IRQ 3 and 4. They are
not changing during cross-link run.

>>>> I then changed the example a little: I let write task only
>>>> write 4 characters and instruct read task to read 10 characters.
>>>> I thought the read task will tell me when that only 4 characters
>>>> is read. But to my surprise, it waited until write-task
>>>> filled all 10 characters before finish reading. How can I
>>>> change the code to just do the read to whatever charaters
>>>> are avaliable without waiting to fill all the characters I
>>>> asked for? I will use this capability to read a GPS. It's
>>>> output length is unknow before reading.
>>>
>>> Setting the config rx timeout to RTSER_TIMEOUT_NONE should help.
>>>
>> Thanks for the suggestion, I will try that.
Yes, changing the rx timeout can read 4 characters. That is now working.

>>>> Most GPS can also produce a precisive time pulse when data
>>>> is ready. Is it be possible to connect this to a pin in rs232 (CTS, for example)
>>>> to triger a IRQ so the data can be read in a timely manner?
>>>
>>> That depends on the signals, I can imagine. I'm not a hardware guy but I
>>> know that many GPS receiver come with a read-to-use RS232 interface.
>>>
>>> Wolfgang.
>>>
>> Yes, you are right. My GPS has a rs232 port and I am trying
>> to use it. The GPS just dump out some information to the
>> rs232 port every 0.1 second. I am just trying to get the information
>> in a timely fashion. I thought that the extra time
>> pulse from the GPS can help.
>
> Just reading out the received data should be fine. They will generate an
> interrupt anyway.
>
> Wolfgang.
>
That is great. If I can get this serial IRQ to work, I don't have to
deal with the time pulse signal. The original idea is from a book. It
states that GPS precision time pulse should be used to drive data
acquisition action.

Thanks a lot.

Everett


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [Xenomai-help] RTDM rs232 strange behavior
  2010-06-08  1:32       ` Everett Wang
@ 2010-06-08  2:46         ` Everett Wang
  0 siblings, 0 replies; 7+ messages in thread
From: Everett Wang @ 2010-06-08  2:46 UTC (permalink / raw)
  To: Wolfgang Grandegger; +Cc: xenomai

Hi Wolfgang,

I overlooked the irq thing. If I look at the /proc/xenomai/irq
I see this when cross-link is not running:
everett@domain.hid$ cat irq
everett@domain.hid$ cat irq
IRQ         CPU0
300:       11671         [timer]
322:           0         [virtual]

when cross-link is running:
everett@domain.hid$ cat irq
IRQ         CPU0
  3:        1320         rtser1
  4:         165         rtser0
300:       14785         [timer]
322:         500         [virtual]
The IRQ 3 and 4 numbers are increasing rapidly. So it seems to be
working fine. What a normal time lag is expect between write
and read for X86 machine?

Thanks,

Everett

On Tue, Jun 8, 2010 at 9:32 AM, Everett Wang <everteq@domain.hid> wrote:
> Hi Wolfgang,
>
> Thanks for your quick email. :-)
>
> On Mon, Jun 7, 2010 at 9:17 PM, Wolfgang Grandegger <wg@domain.hid> wrote:
>> On 06/07/2010 02:07 PM, Everett Wang wrote:
>>> I am so glad that Wolfgang is able to help giving suggestions. Thanks
>>> a lot. That is very useful for new users. :-)
>>>
>>> On Mon, Jun 7, 2010 at 4:05 PM, Wolfgang Grandegger <wg@domain.hid> wrote:
>>>> On 06/05/2010 04:22 AM, Everett Wang wrote:
>>>>> Hi All,
>>>>>
>>>>> I am playing around with xenomai and RTDM serial driver on a
>>>>> 1.7Ghz Pentium-M machine running xenomai 2.5.3. The example cross-link
>>>>> produced this result:
>>>>>
>>>>> main : starting read-task
>>>>>  Nr |   write->irq    |    irq->read    |   write->read   |
>>>>> -----------------------------------------------------------
>>>>>   0 |          118948 |          614135 |          733083
>>>>>   1 |          115598 |          614281 |          729879
>>>>>   2 |          108917 |          614982 |          723899
>>>>>   3 |          106101 |          616560 |          722661
>>>>>   4 |          113457 |          614971 |          728428
>>>>>   5 |          110358 |          614265 |          724623
>>>>>   6 |          106499 |          614406 |          720905
>>>>>   7 |          110363 |          615015 |          725378
>>>>>   8 |          115478 |          614840 |          730318
>>>>>   9 |          110766 |          614168 |          724934
>>>>>  10 |          108986 |          616435 |          725421
>>>>>  11 |          108030 |          614299 |          722329
>>>>>  12 |          109369 |          614420 |          723789
>>>>>  13 |          105862 |          614456 |          720318
>>>>>  14 |          110428 |          616301 |          726729
>>>>>
>>>>> Is 0.7 millisecond between write and read a reasonable number?
>>>>
>>>> No, at least not for a baudrate of 115200. Does the "latency" test
>>>> report reasonable latency figures? And how did you load xeno_16550A.ko?
>>>>
>>> The latency test seems very reasonable:
>>> 4 microseconds when I try to open several browers at the
>>> same time:
>>>
>>> mini:/usr/xenomai/share/xenomai/testsuite/klatency# ./run
>>> *
>>> *
>>> * Type ^C to stop this application.
>>> *
>>> *
>>> == Sampling period: 100 us
>>> == Test mode: in-kernel periodic task
>>> == All results in microseconds
>>> warming up...
>>> RTT|  00:00:01  (in-kernel periodic task, 100 us period, priority 99)
>>> RTH|-----lat min|-----lat avg|-----lat max|-overrun|----lat best|---lat worst
>>> RTD|      -0.722|      -0.618|       0.755|       0|      -0.722|       0.755
>>> RTD|      -0.721|      -0.616|       0.803|       0|      -0.722|       0.803
>>> RTD|      -0.708|      -0.616|       0.876|       0|      -0.722|       0.876
>>> RTD|      -0.722|      -0.616|       0.854|       0|      -0.722|       0.876
>>> RTD|      -0.708|      -0.617|       0.954|       0|      -0.722|       0.954
>>> RTD|      -0.709|      -0.615|       0.682|       0|      -0.722|       0.954
>>> RTD|      -0.724|      -0.595|       0.918|       0|      -0.724|       0.954
>>> RTD|      -0.728|      -0.477|       2.785|       0|      -0.728|       2.785
>>> RTD|      -0.725|      -0.526|       2.721|       0|      -0.728|       2.785
>>> RTD|      -0.729|      -0.512|       2.609|       0|      -0.729|       2.785
>>> RTD|      -0.726|      -0.485|       4.483|       0|      -0.729|       4.483
>>> RTD|      -0.726|      -0.479|       4.142|       0|      -0.729|       4.483
>>> RTD|      -0.723|      -0.542|       2.735|       0|      -0.729|       4.483
>>> RTD|      -0.728|      -0.580|       1.896|       0|      -0.729|       4.483
>>> RTD|      -0.728|      -0.540|       2.196|       0|      -0.729|       4.483
>>> RTD|      -0.726|      -0.566|       1.831|       0|      -0.729|       4.483
>>> RTD|      -0.711|      -0.607|       1.768|       0|      -0.729|       4.483
>>> RTD|      -0.712|      -0.591|       1.050|       0|      -0.729|       4.483
>>> RTD|      -0.721|      -0.615|       1.116|       0|      -0.729|       4.483
>>> RTD|      -0.712|      -0.612|       0.694|       0|      -0.729|       4.483
>>> RTD|      -0.721|      -0.614|       0.782|       0|      -0.729|       4.483
>>> ^CRTT|  00:00:22  (in-kernel periodic task, 100 us period, priority 99)
>>> RTH|-----lat min|-----lat avg|-----lat max|-overrun|----lat best|---lat worst
>>> RTD|      -0.724|      -0.610|       1.213|       0|      -0.729|       4.483
>>> ---|------------|------------|------------|--------|-------------------------
>>> RTS|      -0.729|      -0.554|       4.483|       0|    00:00:24/00:00:24
>>> mini:/usr/xenomai/share/xenomai/testsuite/klatency#
>>>
>>> The user space latency is also reasonable at 10 microseconds:
>>> mini:/usr/xenomai/share/xenomai/testsuite/latency# ./run
>>> *
>>> *
>>> * Type ^C to stop this application.
>>> *
>>> *
>>> == Sampling period: 100 us
>>> == Test mode: periodic user-mode task
>>> == All results in microseconds
>>> warming up...
>>> RTT|  00:00:01  (periodic user-mode task, 100 us period, priority 99)
>>> RTH|----lat min|----lat avg|----lat max|-overrun|---msw|---lat best|--lat worst
>>> RTD|      0.245|      0.391|      2.736|       0|     0|      0.245|      2.736
>>> RTD|      0.132|      0.663|      7.012|       0|     0|      0.132|      7.012
>>> RTD|      0.248|      0.871|      6.954|       0|     0|      0.132|      7.012
>>> RTD|      0.245|      0.650|      5.741|       0|     0|      0.132|      7.012
>>> RTD|      0.213|      1.009|     10.657|       0|     0|      0.132|     10.657
>>> RTD|      0.247|      0.902|      8.936|       0|     0|      0.132|     10.657
>>> RTD|      0.177|      0.776|      6.978|       0|     0|      0.132|     10.657
>>> RTD|      0.246|      0.735|      7.571|       0|     0|      0.132|     10.657
>>> RTD|      0.245|      0.918|      8.821|       0|     0|      0.132|     10.657
>>> RTD|      0.127|      0.387|      3.423|       0|     0|      0.127|     10.657
>>> RTD|      0.138|      0.429|      2.977|       0|     0|      0.127|     10.657
>>> RTD|      0.096|      0.357|      3.100|       0|     0|      0.096|     10.657
>>> RTD|      0.133|      0.357|      3.019|       0|     0|      0.096|     10.657
>>> RTD|      0.132|      0.356|      2.246|       0|     0|      0.096|     10.657
>>> RTD|      0.140|      0.382|      5.711|       0|     0|      0.096|     10.657
>>> RTD|      0.131|      0.361|      2.041|       0|     0|      0.096|     10.657
>>> ^C---|-----------|-----------|-----------|--------|------|-------------------------
>>> RTS|      0.096|      0.596|     10.657|       0|     0|    00:00:16/00:00:16
>>> mini:/usr/xenomai/share/xenomai/testsuite/latency#
>>>
>>> I load driver using this before running cross-link examples:
>>>
>>> setserial /dev/ttyS0 uart none
>>> setserial /dev/ttyS1 uart none
>>> insmod /lib/modules/2.6.32.11-xeno/kernel/drivers/xenomai/serial/xeno_16550A.ko
>>> io=0x3f8,0x2f8 irq=4,3 tx_fifo=10,20 start_index=0
>>
>> Are the interrupts shared with some other devices. What does
>> /proc/interrupt show when you run the test? Also, the default tx_fifo
>> should be fine. And what does "setserial -G /dev/ttyS0" list before you
>> disable the device (with "uart none").
>>
>
> I look at the bios setting. All irqs are set automatically. Window
> setup indicated no conflict of IRQs. But dmesg has this:
>
>  [    0.356143] Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
> [    0.356143] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
> [    0.356143] serial8250: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A
> [    0.359109] 00:07: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
> [    0.359263] 00:08: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A
>
> I guess the IRQ is shared with something else. But I can't finger our
> what else is using IRQ 3 and 4. The computer has only two serial
> ports.
>
> setserial -G has this:
>
> #  setserial -G /dev/ttyS0
> /dev/ttyS0 uart 16550A port 0x03f8 irq 4 baud_base 115200 spd_normal skip_test
> # setserial -G /dev/ttyS1
> /dev/ttyS1 uart 16550A port 0x02f8 irq 3 baud_base 115200 spd_normal skip_test
>
> Now I load xeno_16550A.ko with default fifo.
> I also looked at the /proc/interrupt file
> during running of the cross-link
> everett@domain.hid$ cat interrupts
>           CPU0
>  0:      18169   IO-APIC-edge      timer
>  1:       1492   IO-APIC-edge      i8042
>  3:         10   IO-APIC-edge
>  4:          9   IO-APIC-edge
>  7:          0   IO-APIC-edge      parport0
>  8:          2   IO-APIC-edge      rtc0
>  9:          0   IO-APIC-fasteoi   acpi
>  10:          0   IO-APIC-edge      MPU401 UART
>  14:       7835   IO-APIC-edge      ide0
>  15:       6662   IO-APIC-edge      ide1
>  16:       9665   IO-APIC-fasteoi   uhci_hcd:usb1, i915@domain.hid000:00:02.0
>  17:          1   IO-APIC-fasteoi   Intel 82801DB-ICH4
>  18:      28708   IO-APIC-fasteoi   uhci_hcd:usb4, ipw2200
>  19:          0   IO-APIC-fasteoi   uhci_hcd:usb3
>  20:       3660   IO-APIC-fasteoi   eth0
>  23:          2   IO-APIC-fasteoi   ehci_hcd:usb2
> NMI:          0   Non-maskable interrupts
> LOC:      72987   Local timer interrupts
> SPU:          0   Spurious interrupts
> PMI:          0   Performance monitoring interrupts
> PND:          0   Performance pending work
> TRM:          0   Thermal event interrupts
> THR:          0   Threshold APIC interrupts
> MCE:          0   Machine check exceptions
> MCP:          3   Machine check polls
> ERR:          0
> MIS:          0
>
> I can see IRQ 1, which is used by i8042, as well as local time
> interrupt are increasing. But not IRQ 3 and 4. They are
> not changing during cross-link run.
>
>>>>> I then changed the example a little: I let write task only
>>>>> write 4 characters and instruct read task to read 10 characters.
>>>>> I thought the read task will tell me when that only 4 characters
>>>>> is read. But to my surprise, it waited until write-task
>>>>> filled all 10 characters before finish reading. How can I
>>>>> change the code to just do the read to whatever charaters
>>>>> are avaliable without waiting to fill all the characters I
>>>>> asked for? I will use this capability to read a GPS. It's
>>>>> output length is unknow before reading.
>>>>
>>>> Setting the config rx timeout to RTSER_TIMEOUT_NONE should help.
>>>>
>>> Thanks for the suggestion, I will try that.
> Yes, changing the rx timeout can read 4 characters. That is now working.
>
>>>>> Most GPS can also produce a precisive time pulse when data
>>>>> is ready. Is it be possible to connect this to a pin in rs232 (CTS, for example)
>>>>> to triger a IRQ so the data can be read in a timely manner?
>>>>
>>>> That depends on the signals, I can imagine. I'm not a hardware guy but I
>>>> know that many GPS receiver come with a read-to-use RS232 interface.
>>>>
>>>> Wolfgang.
>>>>
>>> Yes, you are right. My GPS has a rs232 port and I am trying
>>> to use it. The GPS just dump out some information to the
>>> rs232 port every 0.1 second. I am just trying to get the information
>>> in a timely fashion. I thought that the extra time
>>> pulse from the GPS can help.
>>
>> Just reading out the received data should be fine. They will generate an
>> interrupt anyway.
>>
>> Wolfgang.
>>
> That is great. If I can get this serial IRQ to work, I don't have to
> deal with the time pulse signal. The original idea is from a book. It
> states that GPS precision time pulse should be used to drive data
> acquisition action.
>
> Thanks a lot.
>
> Everett
>


^ permalink raw reply	[flat|nested] 7+ messages in thread

* Re: [Xenomai-help] RTDM rs232 strange behavior
  2010-06-05  2:22 [Xenomai-help] RTDM rs232 strange behavior Everett Wang
  2010-06-07  8:05 ` Wolfgang Grandegger
@ 2010-06-09  6:19 ` Wolfgang Grandegger
  1 sibling, 0 replies; 7+ messages in thread
From: Wolfgang Grandegger @ 2010-06-09  6:19 UTC (permalink / raw)
  To: Everett Wang; +Cc: xenomai

On 06/05/2010 04:22 AM, Everett Wang wrote:
> Hi All,
> 
> I am playing around with xenomai and RTDM serial driver on a
> 1.7Ghz Pentium-M machine running xenomai 2.5.3. The example cross-link
> produced this result:
> 
> main : starting read-task
>  Nr |   write->irq    |    irq->read    |   write->read   |
> -----------------------------------------------------------
>   0 |          118948 |          614135 |          733083
>   1 |          115598 |          614281 |          729879
>   2 |          108917 |          614982 |          723899
>   3 |          106101 |          616560 |          722661
>   4 |          113457 |          614971 |          728428
>   5 |          110358 |          614265 |          724623
>   6 |          106499 |          614406 |          720905
>   7 |          110363 |          615015 |          725378
>   8 |          115478 |          614840 |          730318
>   9 |          110766 |          614168 |          724934
>  10 |          108986 |          616435 |          725421
>  11 |          108030 |          614299 |          722329
>  12 |          109369 |          614420 |          723789
>  13 |          105862 |          614456 |          720318
>  14 |          110428 |          616301 |          726729
> 
> Is 0.7 millisecond between write and read a reasonable number?

I just ran this test on my PC and got similar results. The figures are
in *nanoseconds*. And yes, stupid me, 0.7 *milli-seconds* is a resonable
number for 115200: (2 * 4 bytes * 10 bits-per-byte) / 115200 bits/sec.

Wolfgang.


^ permalink raw reply	[flat|nested] 7+ messages in thread

end of thread, other threads:[~2010-06-09  6:19 UTC | newest]

Thread overview: 7+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2010-06-05  2:22 [Xenomai-help] RTDM rs232 strange behavior Everett Wang
2010-06-07  8:05 ` Wolfgang Grandegger
2010-06-07 12:07   ` Everett Wang
2010-06-07 13:17     ` Wolfgang Grandegger
2010-06-08  1:32       ` Everett Wang
2010-06-08  2:46         ` Everett Wang
2010-06-09  6:19 ` Wolfgang Grandegger

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