From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 11318 invoked by alias); 17 Feb 2006 22:18:08 -0000 Received: (qmail 11303 invoked by uid 22791); 17 Feb 2006 22:18:07 -0000 X-Spam-Check-By: sourceware.org Received: from www.mcmanis.com (HELO www.mcmanis.com) (66.125.189.29) by sourceware.org (qpsmtpd/0.31) with SMTP; Fri, 17 Feb 2006 22:18:05 +0000 Received: (qmail 93354 invoked from network); 17 Feb 2006 22:24:31 -0000 Received: from unknown (HELO CMCMANIS-LXP.mcmanis.com) (198.95.226.240) by www.mcmanis.com with SMTP; 17 Feb 2006 22:24:31 -0000 Message-Id: <6.1.0.6.0.20060217135240.01ed3498@66.125.189.29> X-Sender: cmcmanis@66.125.189.29 (Unverified) Date: Fri, 17 Feb 2006 22:18:00 -0000 To: "vasantha.rajan" , From: Chuck McManis Cc: ecos-discuss@ecos.sourceware.org In-Reply-To: <200602171910.56724.vasantha.rajan@cranessoftware.com> References: <200602171910.56724.vasantha.rajan@cranessoftware.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; format=flowed Mailing-List: contact ecos-discuss-help@ecos.sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: ecos-discuss-owner@ecos.sourceware.org Subject: Re: [ECOS] CYGNUM_HAL_RTC_PERIOD X-SW-Source: 2006-02/txt/msg00184.txt.bz2 At 05:40 AM 2/17/2006, vasantha.rajan wrote: >I have some doubt in CYGNUM_HAL_RTC_PERIOD. I will list my doubts > >1. In my code I just want to trigger my alarm for some micro seconds (say for >25 us) That is a very short time for most systems. Yours especially. Ignoring other aspects (like how the RTC timer is configured) for the moment, realize that on average the ARM9 achieves about 1.5 cycles per instruction. (This from the ARM9 FAQ) and that when clocked at 150Mhz (which the Excalibur board apparently is) that's roughly 100 million instructions per section. So 25 micro seconds is roughly 2500 instructions. At 3 instructions per line of C code (on average) that's about 833 lines of C code between clock ticks. Perhaps you need some specialized hardware to meet this timing requirement? --Chuck -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss