Did you try "fflush()" after the "write()" syscall?
-----Original Message----- From: uclinux-dev-boun...@uclinux.org [mailto:uclinux-dev-boun...@uclinux.org] On Behalf Of Alexey Goncharov Sent: Monday, July 05, 2010 3:58 AM To: uClinux development list Subject: [uClinux-dev] how to decrease serial port tx latency? Hi folks, I'm working on an application that runs under uClinux on a custom board (arm7) and deals with serial port. It's kind of a data acquisition app that uses serial port to yield the data from remote sensors. Application uses "request->response" technique: sends an appropiate command to the sensors periodically and waits response from them. Sensors work fine and respond within 15-25 ms right after they get the command. But application doesn't work as we want. The problem is that the time between "write" syscall (write to serial port) and the moment when the data physically appears on a pin is huge - up to 200 ms and it varies from one cycle to another. And it's unacceptable for us. You may find the configuration of serial port which i'm using at the moment. I have only 2 questions to the whole maillist: 1. how to decrease this latency down to ... 50 ms (i guess, would be fine)? 2. what information do you want me to provide to help fixing this issue? Thank you! -- Agava Design Bureau 620026, Russia, Yekaterinburg, Bazhova str. 174 tel./fax. +7 (343) 262-92-76, 262-92-78, 262-92-87 http://kb-agava.ru ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________ ______________________________________________________________________ This email has been scanned by the MessageLabs Email Security System. For more information please visit http://www.messagelabs.com/email ______________________________________________________________________
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