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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

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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