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. _______________________________________________ Xenomai-help mailing list [email protected] https://mail.gna.org/listinfo/xenomai-help
