I use an RTOS every day, but I was wondering why a lot of people still don't use one? I find it a very useful tool, but I still run into a lot embedded engineers that don't use one, why? Too hard? To expensive? I don't need one? Never bothered to learn? My boss said no way?
I don't use an RTOS because...
Started by ●January 12, 2005
Reply by ●January 13, 20052005-01-13
Paul@Rasdoc.com wrote:> I use an RTOS every day, but I was wondering why > a lot of people still don't use one? > I find it a very useful tool, but I still run into a lot > embedded engineers that don't use one, why? > > > Too hard? > > To expensive? > > I don't need one? > > Never bothered to learn? > > My boss said no way? > >I almost always use RTOS's these days, but: If the application is way small, or if it requires very high reliability, then an RTOS doesn't make sense. Otherwise its useful. If you've never ever used an RTOS before you would pull the threshold much higher -- learning to effectively use an RTOS is a pretty steep curve for any one project, but it sure makes sense in the long run. -- Tim Wescott Wescott Design Services http://www.wescottdesign.com
Reply by ●January 13, 20052005-01-13
On Wed, 12 Jan 2005 19:57:30 -0800, Paul@Rasdoc.com wrote in comp.arch.embedded:> I use an RTOS every day, but I was wondering why > a lot of people still don't use one?Use them in some places, either commercial or custom built in house, don't use them in others.> I find it a very useful tool, but I still run into a lot > embedded engineers that don't use one, why? > > Too hard? > > To expensive?An RTOS is expensive in terms of code space, RAM space, and execution time even it has no direct monetary cost for source or run-time licenses. How expensive it is in those terms relative to the rest of the application depends on a lot of factors.> I don't need one?I don't use one when I don't need one. There are two major reasons that I can see for using an OS (RT or not) in an embedded system: 1. It comes with a lot of drivers that you would need to build separately, such as USB stack, TCP/IP stack, file system, etc. 2. (RTOS only) when you need to respond to a mix of asynchronous events with different priorities. In this case, an RTOS with priority based preemptive multitasking and good message passing facilities can be a necessity. On the other hand, something like an 8-bit micro built into a hand control device that has to debounce user button presses and send messages over a serial or CAN bus when they happen doesn't need one.> Never bothered to learn?Know how to use 'em, know how to make 'em for special purposes.> My boss said no way?My boss knows enough to leave such decisions to me, unless the financial cost is significant. -- Jack Klein Home: http://JK-Technology.Com FAQs for comp.lang.c http://www.eskimo.com/~scs/C-faq/top.html comp.lang.c++ http://www.parashift.com/c++-faq-lite/ alt.comp.lang.learn.c-c++ http://www.contrib.andrew.cmu.edu/~ajo/docs/FAQ-acllc.html
Reply by ●January 13, 20052005-01-13
I drive a Truck every day, but I was wondering why a lot of people still don't use one? I find it a very useful tool, but I still run into a lot embedded engineers that don't use one, why? Too hard? To expensive? I don't need one? Never bothered to learn? My boss said no way? Simple CPUs and simple project do not need them. Bigger project MUST use them. Then of course there is the projects in the middle that could go either way. The engineer needs to decided what the project needs. Cost , learning curve, memory, and familiarity are all part of the equation.
Reply by ●January 13, 20052005-01-13
Paul@Rasdoc.com wrote :> Too hard?dont know> To expensive?sometimes, everything is expensive compared do FreeBSD and Linux> I don't need one?yes, but i'm lucky> Never bothered to learn?yes> My boss said no way?I'm not that schizofrenic :)) Pozdrawiam. -- RusH // http://randki.o2.pl/profil.php?id_r=352019 Like ninjas, true hackers are shrouded in secrecy and mystery. You may never know -- UNTIL IT'S TOO LATE.
Reply by ●January 13, 20052005-01-13
Paul@Rasdoc.com wrote:> I use an RTOS every day, but I was wondering why > a lot of people still don't use one?2k flash, 128 bytes RAM, a lot to do. Nuff said? Or requirements are simple. I don't want to use a PowerPC and 256G RAM and a compact flash boot disk just to flash a couple of LEDs. Though it looks better on the CV. I use an RTOS if I need one and have the space- I even wrote one (very simple one) once. Paul Burke
Reply by ●January 13, 20052005-01-13
>Subject: I don't use an RTOS because... >From: Paul@Rasdoc.com >Date: 13/01/2005 03:57 GMT Standard Time >Message-id: <p8sbu0dm1676t3emidlbrq31skvhfq4dvo@4ax.com> > > >I use an RTOS every day, but I was wondering why >a lot of people still don't use one? >I find it a very useful tool, but I still run into a lot >embedded engineers that don't use one, why? >They are only really usefull for big projects, especialy team efforts.
Reply by ●January 13, 20052005-01-13
CBarn24050 wrote:>>I use an RTOS every day, but I was wondering why >>a lot of people still don't use one? >>I find it a very useful tool, but I still run into a lot >>embedded engineers that don't use one, why? >> > > > They are only really usefull for big projects, especialy team efforts.Not really. They are very useful when you need to do unrelated tasks on a single system, or have a time sensitive control task and a number of other tasks (human interface, setup, management) that you would like to operate transparently while the main task goes on. Very useful in their place, can be very expensive (in resources if not fees) out of place. Paul Burke
Reply by ●January 13, 20052005-01-13
<Paul@Rasdoc.com> wrote in message news:p8sbu0dm1676t3emidlbrq31skvhfq4dvo@4ax.com...> > I use an RTOS every day, but I was wondering why > a lot of people still don't use one?As others have said, RTOSs have their uses. But they're not a panacea. Most of my applications are cost-sensitive and high-reliability. If I had to choose one reason for *not* using an RTOS, it would be reliability. I'm a big fan of the KISS principle, and I'm adept at writing complex but reliable schedulers. Why should I spend money on something that contributes bloat and reduces reliability? Steve http://www.fivetrees.com
Reply by ●January 13, 20052005-01-13
Paul Burke wrote:> CBarn24050 wrote: > >>> I use an RTOS every day, but I was wondering why >>> a lot of people still don't use one? I find it a very useful tool, >>> but I still run into a lot embedded engineers that don't use one, why? >>> >> >> >> They are only really usefull for big projects, especialy team efforts. > > > Not really. They are very useful when you need to do unrelated tasks on > a single system, or have a time sensitive control task and a number of > other tasks (human interface, setup, management) that you would like to > operate transparently while the main task goes on. Very useful in their > place, can be very expensive (in resources if not fees) out of place. >In fact, one of the biggest embedded project I've worked to date (+100,000 LOCS) is the only one in which I have not used an RTOS! That's because it was safety-critical, and it was much cheaper to design it as a one-task program and show its safety level this way than to use an RTOS and show its safety level with the several tasks approach.
