> From: [EMAIL PROTECTED] > To: [EMAIL PROTECTED]; [email protected] > Date: Thu, 9 Oct 2008 00:05:32 -0700 > Subject: RE: [ECOS] Is eCos running any background process? > >> From: Yong Chen Tan >> >> Hi, currently I am using polling to capture all my 2238 items >> because the interrupt is not fast enough. For my application, my >> DSYNC pulse is at 4.72us. That means I need to read on every >> 4.72us. My total time required to finish capture 2238 data is >> calculated to be 10.6ms. Based on your analysis saying that eCos >> will actually receive interrupts from system clock every 10ms. Is >> there a way to prevent eCos from doing anything during the >> 10.6ms? Because data is coming in at every 4.72us, so everytime >> when I execute this function, there is bound to be 4 DSYNC values >> not caputred. > > What's probably causing your data loss is the timer DSR. Every 10ms > (typically) the timer generates an IRQ, and the ISR code schedules the timer > DSR code. The ISR probably runs in well under 4.72us, but the DSR takes much > longer. Since all DSRs have higher priority than all threads, this causes > your data loss. > > However all ISRs have a higher priority than all DSRs, too. So if you have > some way of hooking up your DSYNC to an external IRQ line, you can write an > ISR that does nothing but write one byte into the buffer. This should be > able to keep up with the data rate just fine, assuming you're running the > ARM at a typical 166-200MHz speed. > > If you don't have a way to get DSYNC to generate an interrupt, then you've > got a hardware design that isn't going to give you a clean way to accomplish > this, and you'll have to resort to some nasty hack like shutting off > interrupts entirely while you fill the buffer, and possibly suffering a lost > timer interrupt. > > -- > > Ciao, Paul D. DeRocco > Paul mailto:[EMAIL PROTECTED] > > > -- > Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos > and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss >
Hi, thanks for your valuable advice you have given. Is it possible to shut off interrupts entirely? _________________________________________________________________ Join the Fantasy Football club and win cash prizes here! http://fantasyfootball.sg.msn.com -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss
