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Jack very well explained, Thanks.

Iron

I'm listening now to prepare for the Real Time Kernels class that starts today.

Gold

Great lecture with well explained concepts.

Iron

Good slides and very informative lecture. Thank you Sir Jack.

Iron

thanks for a great presentation sir jack, i will be back for day 4 class to finish the class session for 1 week...thanks regards to digikey and design news for education us...

goodnight & good morning to all of you in this class archived...bye!

class presentation is done and now listening with the wonderfule Q & A session...

i am now on slide 22 of the presentation slides...

i just downloaded the presentation slides for references...

good evening sir jack, i am here again for your day 3 class session...

Thanks guys, great presentation on RTOS for the conversation afterwards too.

Iron

Thanks Jack and Alex. Lots of informations.

Iron

Lots of information from many angles

great overview! thanks

Iron

Thank you Jack and Alex for another great discussion.

Iron

Again?  Slide 25?

Iron

18, rather, not 19.

Iron

Good catch Alex, though it sounds like Jack was still talking about slide 19.

Iron

Good presentation may watch again.

Iron

Great overview. Thank you!

Iron

Excellent overview. Wish I could have watched live.

Iron

Good presentation and good Q & A by the group and presenter.  It seems they first want you to write code, then they want you to debug it - what is task partitioning for then?  Also, now they are saying that LOC is not necessarily linked to productivity? :)

For the first time, an archived presentation just completely cut out right around one minute and 45 seconds.  Refresh fixed it though.

Iron

Another great presentation, Jack.  Thanks!

Iron

A GUI would be a good example of a code package to get from a vendor, true?

Iron

Would an RTOS be the chice to use for an electro-mechanicle servomanipulator?

Iron

Is the FORTH language still a viable option for an RTOS?

Iron

Great series! Thanks!!!

Iron

Thanks for the presentation.

the object oriented programming languages are good but using C in an RTOS is greatly more versitile.

Iron

C programming is still alive and well and will not be outdated any time soon. 

Iron

Hardware and software developers have to work together to find a Ucontroller to suit the needs of the design.  I've developed both ways and its always hard to go back and correct the other.

Iron

I've used Micro C for RTOS and it works well.  It has alot of the things they need and is easy to get up and running.

Iron

Good to know.  Thanks.

Iron
very informative, thank you
Iron

Nice presentation. Thanks Jack!

Iron

I looked up the price on the MicroC stuff.  Wow, spendy if you're a small shop doing a simple product.

Iron

and of course http://en.wikipedia.org/wiki/MicroC/OS-II also supports Cortex.  Jack mentions them several times in his lectures.

Iron

Nucleus OS also supports Cortex.  Heard good things about them.

Iron

Salvos works with Cortex:  Salvo

Iron

Here's a list of RTOSs on Wikipedia:  http://en.wikipedia.org/wiki/List_of_real-time_operating_systems

Iron

This was interesting.  Thank you Jack.  I saw you back at the embedded sys con in 2006.  Very interesting.

Iron

Thanks Jack - good presentation.

Which RTOSes can be recommended for processors like ARM Cortex M3/M4?

Iron

Luizcosta, you and your capslock key... XD

Liked the pro/con on "roll your own."  You have an app to write.  Do you *really* want to design and debug your own RTOS while writing that app?  Don't reinvent the wheel.  Save yourself a huge amount of time and purchase an RTOS with good tech support.

 

Gotta run, folks. Thanks for the great qustions!

Iron

Jack, do you know if there is any preference in the Northeast for one RTOS over another? I'm trying to figure out what is locally relevant in RTOSes.

 

No, I haven't seen any regional preferences.

Iron

Jack, do you know if there is any preference in the Northeast for one RTOS over another? I'm trying to figure out what is locally relevant in RTOSes.

oh, well, back to the grindstone for another 2 hours. Thanks everybody!

Iron

that's why my toothbrush runs on my right hand, not on battery :-)

Iron

Jack, are there any viable alternatives to the C Standard Library for embedded work? Legacy mistakes like "printf" abound...

 

The problem is that the library tends to be very compiler-dependent, and so is supplied by the compiler vendor. There are a few minor replacements, like the SMX GoFast floating point library I mentioned yesterday.

Iron

security in embedded systems ... I imagine that is a very different beast than on "normal" computers

 

I think this is a hugely-ignored issue. Heck, if your USB toothbrush got infected it could pass that around.

Iron

Jack, are there any viable alternatives to the C Standard Library for embedded work? Legacy mistakes like "printf" abound...

security in embedded systems ... I imagine that is a very different beast than on "normal" computers

Iron

@caa028: makes sense, I didn't think of that.

Iron

Comment about selecting an RTOS.  If you let the h/w guys pick the ucontroller, you could get stuck trying to find an RTOS that will fit.  That's how I ended up using Salvo because uC just would not fit.  Turn the process around.  Pick the RTOS/IDE that best suits your application, then tell the h/w guys to find you a ucontroller that meets the firmware requirements.

 

Absoultey agreed. The h/w and s/w people need to work together to pick a CPU. Seldom happens, though.

Iron

JACK, I THINK EVERYONE WILL AGREE THAT WE COULD STAY HERE WITH YOU FOR ANOTHER HOUR OR MORE. THANK YOU FOR THE GREAT INFORMATION.

Iron

@ s.schmiedl - the reason could be that you want to reuse a large project... etc...

Iron

> The former requries more CPU horsepower. I think all hypervisors are for 32 bit CPUs.

that's kind of my point: why would I want to use that when I could have it in another way?

 

Oh, well, a lot of systems are on 32 anyway. And a huge upside for hypervisors is the security they can bring along. Again, Green Hills is the leader in this.

Iron

QNX was wrtten in C and as far as I know it still is develop in such language.

 

Iron

Comment about selecting an RTOS.  If you let the h/w guys pick the ucontroller, you could get stuck trying to find an RTOS that will fit.  That's how I ended up using Salvo because uC just would not fit.  Turn the process around.  Pick the RTOS/IDE that best suits your application, then tell the h/w guys to find you a ucontroller that meets the firmware requirements.

Jack, thank you for one more very informative lecture!

Iron

> The former requries more CPU horsepower. I think all hypervisors are for 32 bit CPUs.

that's kind of my point: why would I want to use that when I could have it in another way?

Iron

Jack, I believe that FreeRTOS is written in C for portability.

 

Yes, it is. Nearly all are.

Iron

if i have a task that takes longer than the basic time tick and must be completed before another task runs do i lengthen the tick or is there a mechanism in the rtos to do that?

 

You can dynamically raise the priority, and lower it when done.

Iron

Jack, I believe that FreeRTOS is written in C for portability.

Jack, I've taking some trainint at QNX, but they are indeed expensive and the courses go way too fast. I meant YOUR OWN TRAINING or WEBINAR.

 

Sorry, no. Not enough hours in the day!

Iron

It might be better to use a chip that is too small for C Plus Plus in those classes, so students understand the need to limit themselves. ;)

let me approach it from another angle: virtualization vs. decomposition to AMP?

 

The former requries more CPU horsepower. I think all hypervisors are for 32 bit CPUs.

Iron

Jack, I've taking some trainint at QNX, but they are indeed expensive and the courses go way too fast. I meant YOUR OWN TRAINING or WEBINAR.

Iron

My  RTOS students frequently ask " why not C+ if we are using QNX Momentics anyway"? What is your answer?

 

I should have been clearer. A lot of people use C with RTOSes. But no RTOS I know of is written in C .

Iron

luizcosta, no issue, so long as C Plus Plus fits in your requirements. However, you should make the point that your students SHOULD get used to C, for embedded requirements that need it.

What database do you recommend for a RTOS?

 

I don't have any to recommend. Embedded databases have been pushed by a couple of companies. To my knowledge all have gone bust.

Iron

laxman, the more important question is whether that thread can be preempted or not. A thread can take more than one tick, IF it is safe to preempt it. Otherwise, extend the tick.

let me approach it from another angle: virtualization vs. decomposition to AMP?

Iron

My  RTOS students frequently ask " why not C+ if we are using QNX Momentics anyway"? What is your answer?

 

Iron

What database do you recommend for a RTOS?

Jack, do you have another RTOS training to recommend?

 

I think Netrino does some, but it's not free. Sometimes there's some at the Embedded Systems Conference (now called "Design").

Iron

if i have a task that takes longer than the basic time tick and must be completed before another task runs do i lengthen the tick or is there a mechanism in the rtos to do that?

Iron

@s.schmiedl - large scale embedded vs small scale...

Iron

somehow I have a cognitive problem with "embedded" and "virtualization". Am I the only one?

 

Ah, but this field is so big it's hard to even define "embedded." Some really big systems are embedded. But I know what you mean!

Iron

Jack, do you have another RTOS training to recommend?

Iron

schmiedl, RTOSes are very small. :)

When using something like FreeRTOS, how do you program in it.  Do you use C like on the PIC32?

 

Yes, it's all in C.

Iron

somehow I have a cognitive problem with "embedded" and "virtualization". Am I the only one?

Iron

kenward, do the world a favor, and edit the Wikipedia page on Salvo. :)

When using something like FreeRTOS, how do you program in it.  Do you use C like on the PIC32?

Iron

I was about to ask the same question about virtualization options for embedded...
Thank you, Jack - I'll have to look closer at Green Hills hypervisor

Iron

Jack, I hear a lot about virtualization from you. What is available to run virtualization in the embedded world?

 

Green Hills has a hypervisor for embedded work.

Iron

kenward, while it is not a personal priority, we have LOTS of biotech companies in the Northeast. It's good to know. :)

a resistor in series with signal if signal is not terminated will limit current to ic and protect diodes from over current

Iron

kenstan: you say you have a relay. Be sure that you have a reverse diode accross the coils or a zener or other snubber to stop the spikes where they are generated; kill noise as quick as possible at the source and at all I/O line.

Iron

Salvo is a cooperative RTOS.  $1200 gets you the source, tech support, no per-unit royalties.  The FDA will sign off on it as well, unlike many other RTOS's.  If you're not doing a med device then maybe you don't care about the FDA...

Jack, I hear a lot about virtualization from you. What is available to run virtualization in the embedded world?

Iron

Jack, the C Standard Library was never really built to be Hard Real-Time. Things like "printf", for instance, are a disaster. Is there an alternative for Hard Real-Time systems?

A diode from signal lines to supplies helps save ICs from spikes

 

Just make sure it's aimed the right way!

Iron

A diode from signal lines to supplies helps save ICs from spikes

Iron

Oh, Jack, for future presentations, you should talk more about coroutines.

 

Good point. Z-Wold's Dynamic C has built-in coroutine support.

Iron

Great presentation Jack. I now have plenty of resources to round up.

kenstan your spike is probably not just on the signal line but maybe pwr and ground (at opto)

Iron

how can i prevent spike from affecting my mcu even after using optocoulper

 

That's a huge subject! There are a million ways a spike can affect an MCU.

Iron

Oh, Jack, for future presentations, you should talk more about coroutines.

how can i prevent spike from affecting my mcu even after using optocoulper

Iron

kenward, is Salvo coroutine based?

The goal of an RTOS is to do its job very efficiently. Naturally, different RTOSes do this job better than others.

How about dual boot embedded system where two options are "normal" and "extra debugs"?


Sure, makes sense if the system is resource-constrained. A lot of people just leave a debug monitor in the code all the time.

Iron

For an implanted class 2 med device, I used a PIC18F45J10 (32k of flash, 1k of ram).  Using Salvo required 4k of flash and 254 bytes of ram, to run 13 tasks.  Note that Salvo is not pre-emptive, but it is deterministic.  No RMA hand-waving.  

Thanks for the informative presentation, Jack.

Nothing was ever mentioned about the TIME overhead eaten by RTOS.  And time eats power most of the time. Can you expand on this?

 

Sure. An RTOS will eat time. But very, very little. Context switches can be on the order of a handful of microseconds, depending on CPU, clock, etc.

Iron

The FreeRTOS manual is good for people like me with no experience with RTOS. It starts out discussing Scheduling strategies and explains why some things work and others don't.  It also discusses priorities.

Iron

How about dual boot embedded system where two options are "normal" and "extra debugs"?

 

Iron

Nothing was ever mentioned about the TIME overhead eaten by RTOS.  And time eats power most of the time. Can you expand on this?

 

Gold

Jack, any experience with Earliest Deadline First scheduling?

 

Lately there's been a lot of talk about EDF. I have yet to see a system that uses it, though.

Iron

TT: you made me read "Easter Deadline First" scheduling ...

Iron

is there specialised Mcu for driving Dc motor , i used atmel 89c52 but it hangs few seconds the motor ic connected to the bidirectional relay driver

 

Sorry, I really don't know. I have seen some CPUs with motor drivers, but can't think of their names off-hand.

Iron

Jack, any experience with Earliest Deadline First scheduling?

thank you Jack for a great presentation

Iron

where can I learn about scheduling strategies?

 

Wikipedia has good references on this.

Iron

Does it make sense to dual boot an embedded system with RTOSes?

 

I guess if there's a good reason to, though I can't think of any. Today instead of dual boot more people are thinking in terms of virtualization to run multiple OSes.

Iron

is there specialised Mcu for driving Dc motor , i used atmel 89c52 but it hangs few seconds the motor ic connected to the bidirectional relay driver

Iron

where can I learn about scheduling strategies?

Iron

Just to understand further if an RTOS is managing an AMP, how will it save stack for one core and run it on the other one if the architecture does not match eg register set etc?

 

Like I said, you'll be running a copy of the RTOS on all of the cores. The implementation will vary between RTOSes. Best resources on this are QNX and Green Hills' Integrity.

Iron

Does it make sense to dual boot an embedded system with RTOSes?

thanks, jack21, that's a memory range I can handle .-)

Iron

I'm sure that depends on the RTOS, krana.

Just to understand further if an RTOS is managing an AMP, how will it save stack for one core and run it on the other one if the architecture does not match eg register set etc?

Iron

What's the size of the smallest RTOS (firmware, not source code), you've used?
How much RAM does one actually need to use an RTOS to handle, say, half a dozen tasks?

 

For a small OS like FreeRTOS you're talking probably tens of bytes of RAM per task, plus some constant overhead.

Iron

krana, the goal of RTOS development is to satisfy every possible combination of threads, periodic or not. The relevant issue is the extent to which a given RTOS achieves that goal.

What is the difference between mutex and binary semaphore?

 

Essentially the same thing. Neither can count.

Iron

Can one RTOS manage AMP (Asymmetric Multi Processing) or do we need multiple RTOSes for this type of system?

 

Some RTOSes will manage several cores, though usually you're running a copy on each. Others are not SMP/AMP aware.

Iron

What's the size of the smallest RTOS (firmware, not source code), you've used?
How much RAM does one actually need to use an RTOS to handle, say, half a dozen tasks?

Iron

What is the difference between mutex and binary semaphore?

Iron

Jack, I have recently purchased an LPC1114 ARM cortex M0 and quite new to this. Before loading a RTOS a bootloader is required from what I understand, whats the best way to select such a bootloader or do I have to write my own?

 

Often the chip vendor will have code. Otherwise you'll have to write it. Or, get an eval board and use the code from that (if legal).

Iron

Some of the tools are awesome! Check out Micrium's uC/Probe.

Thanks Jack.

Iron

Jack, can you say ssomething about POSIX, pthread, and successful program design. I had the impression so far, that QNX provides the programmers with the least headaches.

 

It's hard to speak to that, but I talk to many happy QNX users.

Iron

Can one RTOS manage AMP (Asymmetric Multi Processing) or do we need multiple RTOSes for this type of system?

 

Iron

how to measure interrupt latency?

Lots of ways. Easieist is to scope intr-req and assert a bit when the ISR starts. Measure the difference.

Iron

Jack, I have recently purchased an LPC1114 ARM cortex M0 and quite new to this. Before loading a RTOS a bootloader is required from what I understand, whats the best way to select such a bootloader or do I have to write my own?

 

Iron

Do all compilers exhlbit the execution time of each line of code?

Iron

Jack, any experience with Earliest Deadline First scheduling?

I am using interupt/ timer hold during temperature conversion as part of specs. So there is lag in my timing and it is represented in terms of flicker on seven segment display. How can I avoid it?

 

Jack, can you say ssomething about POSIX, pthread, and successful program design. I had the impression so far, that QNX provides the programmers with the least headaches.

Iron

priority inversion seems to be a big thing using RTOS and there are also ways to avoid that. Buit don't you think they are just workarounds, what is better way of avoiding it?

 

Things like priority ceiling protocol will help a lot.

Iron

Agree - PDF slides would be perfect

Iron

is there specialised Mcu for driving Dc motor , i used atmel 89c52 but it hangs few seconds the motor ic connected to the bidirectional relay driver

Iron

Forth is not an RTOS. Forth is a language.

Iron

Jack, How good are the profiling tools for RTOS based system compared to profiling C subroutines in Non-OS based microcontroller code..

 

Some of the tools are awesome! Check out Micrium's uC/Probe.

Iron

Forth is probably smallest footprint RTOS.

Iron

It is always a good idea to be able to get the source code for the RTOS (or as much as possible) when buying one so you can tweak things if needed

 

I think that is useful, but not all vendors will do that. Also important in case vendor goes out of business, though most will escrow the code for you.

Iron

priority inversion seems to be a big thing using RTOS and there are also ways to avoid that. Buit don't you think they are just workarounds, what is better way of avoiding it?

Iron

Jack, do you know what RTOSes are frequently used in the Northeast?

Have used Forth, is RPN stack based.

Iron

If you get a chance, please join our Digi-Key Continuing Education Center LinkedIn Group at http://linkd.in/yoNGeY

Blogger

Jack, How good are the profiling tools for RTOS based system compared to profiling C subroutines in Non-OS based microcontroller code..

Iron

Relating to the previous session: when should I consider a feature just a task in an RTOS and when it should be partitioned to another MCU?

 

I like to use another CPU when the problem is completely bounded and solved entirely in that CPU. Tasks are more tightly integrated into the code.

Iron

how to measure interrupt latency?

Iron

does anybody remember/have experience with any forth-based systems?

Iron

thanks for the presentation

Iron

Is it recommonded to use external interrupt when OS is introduced in the system?

 

Absolutely - use interrupts to have I/O signal a need for service, for instance.

Iron

It is always a good idea to be able to get the source code for the RTOS (or as much as possible) when buying one so you can tweak things if needed.

Iron

Luiz, you've got Capslock on again...

Relating to the previous session: when should I consider a feature just a task in an RTOS and when it should be partitioned to another MCU?

Do you recommend any book(s), papers that show a good philosophy procedure to write RTOS(es), pieces of it, etc?

Can you write down the name of the books, papers, etc again please?

 

Iron

Thank you Jack and Alex.. Great presentation

Iron

How does android stand up as a near real time type OS

Jack, what RTOSes do you use, and what RTOSes are typically used in different parts of the country? In particular, I'd like to know what RTOSes are typically used in the Northeast!

 

I don't think there are any regional diffs in the USA. In Europe we see more of Enea, etc.

Iron

JACK, HOW ARE THE OS VENDORS GOING TO OFFER TIME ESTIMATES, WHEN THE CODE SEGMENTS HAD CALLS TO FUNCTIONS?

Iron

audio has just ended

Iron

Is it recommonded to use external interrupt when OS is introduced in the system?

Thank you Jack and Alex.

Great Presentation.

Iron

Thanks Jack - Another great discussion

 

Iron

Thank you for the presentation

Iron

Jack, once again, Thanks!

Iron

Good intro for RTOS from Jack.. Have lot to read and understand in this topic...

Iron

Do you recommend any book(s), papers that show a good philosophy procedure to write RTOS(es), pieces of it, etc?

Iron

Here is a fair link for RTOS selection from the Embedded Systems Glossary:

http://www.netrino.com/Embedded-Systems/How-To/RTOS-Selection

 

Iron

Jack, what RTOSes do you use, and what RTOSes are typically used in different parts of the country? In particular, I'd like to know what RTOSes are typically used in the Northeast!

Another great class- Thanks!

Iron

no audio for a few seconds

Iron

FrankBishop, you can usually pick whatever time scale you like as a variable. Some RTOSes will have different limits than others, but the one that typically operates in the time scale you want will likely be better for your application.

FreeRTOS from the UK really is free but the manuals cost $20 and $30 US

Iron

Have a lot to learn about RTOS...Thanks

Iron

Yes Alex. That was a good point on determinism

Iron

Thank you for the presentation.

Iron

for simple round robin tasking, you should set a max runtime for each task so that others can run.

 

Iron

@tenacious It was more of a generic comment trying to see what kind of time is real time

to the nearest sec , milli second uMsec or what

You said during the discussion of slide 27 that the RTOS should be chosen based on the Prossor selected and the Compiler used.  Doesn't it make more more sense to chose a Compiler that is optimised for the Processor selected and the RTOS?

Iron

Is it recommonded to use external interrupt when OS is introduced in the system?

 

Thank you for today's presentation

Iron

@alaskaman66: as long as possible, as short as necessary

Iron

Thank you Jack and all for a great and informative session, see you tomorrow.

Iron

Thanks Jack.  Excellent presentation.  WIll be here tomorrow.

do we have to write our own rtos or are there canned options of the operations options for portions of the systems???

Nuclear Power Plants = Hard Real TIme

Kind of a simple quetion: with Round Robin tasking,  if the duration is user selectable, does one try to choose a duration long enough for most tasks to complete, or are these durations typically only a small percentage of the average task time?

Yes, it is interrupt latency that is critical in real-timesystems.

 

Being able to guarantee a certain level of performance has value to lots of application developers.

Jack, Thanks for your great presentation

 

Iron

Thanks Jack and Alex!

Iron

FrankBishop, it depends on what kind of communications you want. Can you be more specific? What is the application?

thanks jack and alex. great presentation

Iron

When using something like FreeRTOS, how do you program in it.  Do you use C like on the PIC32?

Iron

Are thier different degrees of RTOS I work in the second and millisecond realm with communications

software for communicating over USB, irDA and the network

But I measure in nanoseconds and try and work + or - 50 msec

Thanks Jack, Bruce, and Digikey for this great presentation!

Iron

Thanks Jack. Nice presentation. Is profiling easy in the context of RTOS situation compared to the Raw C code without an Operating System for Microcontroller?

Iron

Thanks, Jack - this refreshes my memory from a RTOS course I took at Wright State back in the late 80s with pdp-11 assembly language.

Iron

another great presentation, jack. thanks.

 

Iron

You probably would need a new kernel. :)

Absolutley great session besides the drop out :-) Thank you Jack and Alex!!

Very valuable information, thank you Jack!

Iron

thanks Jack, today presentation is so great.

Iron

Oh This is totally software-centric

Iron

Jack what is your Faivorite RTOS for Microchip MCU's ?

 

Iron

@Island_Al, bits toggle, works for me with a good scope

Iron

Is there a list of what popular RTOSes are out there, and some advantages/disadvantages/costs etc?

 

Iron

you can use a scope to measure time by setting out bits (toggle)

Gold

@SimonDo: there is not deadlock when it has mutex

A: Actually, mutex is what creates the possibility of deadlock. Only with a low-priority or ill-behaved task taking a mutex and never releasing it, or with two tasks that take multiple mutexes in opposite orders, can deadlock occur. Of course, without a mutex, the shared resources will get corrupted and likely the system will fail, often spectacularly

Iron

@SimonDo - perhaps I'm a little confused.  If 1 task acquires the lock and never relinquishes it, how will other tasks be able to access the resource?

Iron

is there a good resource out there on scheduling strategies for (RT)OSes?

Iron

Jack, change that slide! It looks like "Eleven is greater than Twelve"!

Jack, what about Earliest Deadline First?

does mutex have a way of "timing out" the handling of a task if it "sees" a problem?

 

Iron

How to interrupt kernel? Will ASSEMBLY on porcessor operant do? 

Iron

My way to handle real time reliably is to put the time critical tasks on a separate micro dedicated for the tasks, could also be a multicore.

Iron

I meant mutex will take care of deadlock situation.

Iron

there is not deadlock when it has mutex.

 

Iron

Can Jack address "deadlock"?

Iron

As things stand, if you want a piece of hardware designed for Hard Real-Time needs, you have to settle for a consumer chip that was targeted to general purpose devices, which receive little development priority for Hard Real-Time needs, because the chip companies want to target the general market.

@jrjohns -  yep.  it's called a deadlock

Iron

Can use of a Mutex result in lockup if one task keeps the token (semiphore)?

 

Iron

My main beef is this... as was noted yesterday, developments like Cache make Hard Real-Time performance incredibly complicated. If desktop computing hardware had to satisfy Hard Real-Time needs from the ground up, Commercial Off-The-Shelf hardware would be better designed for Hard Real-Time needs, because everyone wants their desktop to go faster.

slide 18. audio should be fine

Blogger

Let's put it this way, Bruce McLaren... I strongly suspect that Real-Time physics simulations would benefit from a Hard Real-Time OS. I'm sure Video Game developers would appreciate some determinism as well, once they get used to the idea.

BruceMcLaren - not really - some flavors of RTOS can run a desktop OS as a task though

Iron

@TenTech: I admit I'm out of my core expertice, so correct me if I'm talking non-sense. Can desktop OS be made real time without undue effort (undue effort a term I am unable to define)? Is it needed, or just a nice feature to have?

Or pick an RTOS that fits your needs and pick an MCU that it already runs on. :-)

Iron

LeoVargas, that can often be the best alternative, because it tells you what is used locally... look for the more popular classes, and you will get an idea on what is most locally relevant. :)

@FrankBishop - glad to help :)  I just went through an RTOS search in the last few weeks

Iron

these sugesstions are flowing in at high speed

Good thing I can read through the transcript in the weeks ahead

 

Intel bought VXWorks/WindRiver

Iron

Determine your needs, pick an MCU, and see what RTOS(s) are available for it.

Iron

Thanks wikipedia is a great resource

some examples of rtos are traffic control systems, and ncads..

 

Wind River's long-standing RTOS is called VXWorks... I used it in the 90s, it's still around.

 

is bootloader needed in say atem 8952 microcontroller

Iron

Has this has been an example of Running -> Pending -> Ready?

QNX
VxWorks
eCos
Embedded Real Time Linux (uClinux, Spaceflight Linux, RTLinux, ...)
Pumpkin's Salvo
FreeRTOS
TinyOS
AVRx
mCOS II
Etc...

Iron

Yes, and what would be of hardware if no software existed?

Iron

And these other ones mentioned

 

@FrankBishop - wikipedia actually has a pretty good list of RTOSs.  Not totally exhaustive, but a good starting point if you're looking for some to look into.

Iron

Leovargas, try your local IEEE. They often have useful industry related classes, particularly in the Northeast.

I was really curious about FreeRTOS... it seems to be a very popular choice

FrankBishop: I'm always creating custom RTOS, but I've learned alot from uC/OS code

Iron

Ill check out the wind river thanks

 

RTOS memory/resources footprint determines MCU size.  Usually need at least 1MB memory.  1/2MB RAM, 1/2MB ROM(or Flash).  As long as MCU can handle that and have enough timers for RTOS tick, you are good to go.

Iron

I've used TinyOS, QNX, VXWorks although there are alot of options depending on your patform

 

Iron

insert jeopardy theme here

 

Iron

Wind River makes RTOSs

 

Tenacious, where other places do you know where i can find useful classes like this one?

Iron

Hi Jack and Alex! I also had problems of my own, getting stranded on the road.

Iron

alex: is "enviable" a task state ;^)

Iron

Yup... live radio hazards stay the same.

 

"not an enviable task" ... funny!

Iron

Can anyone mention some examples of RTOS they have used

 

@kenstan - it's a piece of code that runs at startup and loads the OS

Iron

I would dispute that, Bruce... Desktop Computers are meant to be generalized computing platforms. As they stand, they are insufficiently generalized for my purposes. That being said, it should be noted that, if Hard Real-Time issues aren't going to be tackled by the desktop community, then COTS computing hardware is going to continue to diverge from Hard Real-Time needs.

I can hear it now

it did drop out a few seconds

didi the audio drop out

 

Iron

Anyway, Hard Real-Time versions of LInux tend to break compatibility with typical Linux software, so there is virtually no compatibility benefit to using a Hard Real-Time version of Linux over something else, for Hard Real-Time applications. That being said, I've heard Xenomai is very good for a Hard Real-Time Linux.

Related to my earlier question: what is the "smallest" MCU, where you'd attempt to run a RTOS on?

Iron

Sounds liek agreat idea, but also sounds like a way to get desktop OSes that don't do what they need to.

More complex requirements always worry me.

Unless, you have a good way to make it easy, of course.

Sure...  Always have a bootloader.

Iron

Do RTOSes also require bootloaders?

Among the different RTOS available is there a way we can decide which one is the most suitable for a particular application ?

 

Iron

@jl - also there is a so called "Priority Inversion" to give CPU time for tasks with lower priority

Iron

@TenTech: You better smile when you say that! :-)

What we really need is for Desktop OSes to become Hard Real-Time. :)

Has its uses but I want my own.

Iron

i believe QNX is real time

Iron

Linux = village bicycle

Iron

if linux sucks, which one is better?

Iron

The kernal has always be tightly controlled 

Does the kernel require all that memory

 

To many flavours of linux to choose from

Iron

Interrupt latency in Unix is horrid.

 

jl - yes, most RTOSs have functions which will cause the task to wait for some period of time.  However, if you find yourself using it, think carefully about your design.  It might make sense to break the operation up into multiple tasks.

Iron

download todays slide deck

Iron

linux is like mutt ... it sucks less :-)

Iron

Linux is great for what it does, but it SUCKS for Hard Real Time!

Butler, try reloading the page, and if that doesn't work, try a different browser.

jl priorities can be used for this.  Sometimes theer's a yield() type of operation.

I don't see anything, I don't hear anything. No error messages. How do I access this lecture?

 

Iron

Whats the best RTOS with alot of free library support for this stuff

do most RTOS systems have a function that releases processing so that other tasks can get some time slice. this would be used in a longer running task

Iron

Thanks, Dan Lafleur and Techhunter. :)

what code sizes are RTOSes? min? typical?

Iron

slide numbers are good

Iron

the audio is much better today, thanks Jack and Alex

Iron

sound  is ok now after refreshing

Iron

your slides are onee number off.you are on slide 6

slide three has nothing. you are on slide 5

@franchzilla, possibly GUI for operator interface to device

Iron

franchzilla, an RTOS is not an alternative to Linux or iOS. An RTOS is a requirements driven thing; if you REQUIRE Hard Real-Time performance, then you use an RTOS. If Soft Real-Time performance is "kind of nice" for your application, you use something more common, like Linux, or whatever operating system runs on your device.

I had tried reloading. But still it is barely audible

Iron

is there another places like this one to keep learning, has been very useful :)

Iron

Is the GUI really important for embedded systems?

 

Audio is just fine for me with my volume set at only 17%

Iron

ok, is loud and clear now.

Iron

Hi folks, having problems with the audio but now it is working :)

Iron

There is problem with audio. Why is it so feebe?

Iron

jack needs to turn up his microphone. I can only just barely hear him

 

Iron

Just got back from a meeting- hope I haven't misssed too much...

Iron

mine was saying blog talk radio too. I just logged out and back in and it started working.

Iron

@danlafleur. Thanks! Refresh helped.

Can the audio be reset?  It is in a loop!

Iron

I think that voice is saying, "Blog Talk Radio", not "Block Talk Radio"

Iron

Audio is feeble at max vol setting, please

Iron

tye refresh, my sound looped as well

Iron

my computer keeps saying 'block talk radio! is it just me?

hello everyone...

 

Iron

cool just got here on time using playbook...

Iron

sound good but repeat the title continuously

Iron

Roll my own - lots of interrupts, some timer-based, some async events

I prefer self-shoveling snow

Iron

QNX, eCos, custom RTOS, and no RTOS

Iron

In our current project, we're using Linux. I asked "why not RTOS" and the answer was just a plain "it's free and people here are used to Linux".

FreeRTOS is a scheduler

 

Iron

Most of the time a state machine.

i want to see snow....cal. dreaming

Iron

°C = 5/9 (°F – 32)
 °F = 9/5°C + 32

Iron

most of my things are real time measurements

Iron

Hi folks! Laxman - I'm near you, in Finksburg, MD

Iron

State machine for my work.

Iron

Chilly morning in Honolulu, 72F.

Iron

Just a reminder... today is change your password day :) Try changing your passwords to make your online life safer

All I know is, here in New England, my father's new ski goggles are going to waste... there hasn't been any snow worthy of note!

Question:  Since today's session is about RTOS, what are most of the participants using?  An RTOS or a simple scheduler / state machine?

 

Iron

For future reference, -40 is exactly the same in Celsius and Farenheit, not -70. :)

We could use a little cold (and snow) here in NJ as well. But strictly in the hills and not on the highways/driveways. Or am I asking for too much :)

Iron

Hi all, 65 in Baltimore, md

Iron

"burying their fuel tanks and lines with snow to bring the fuel temp up a little."  Now that's funny.  I guess the Inuit's knew weather better than the new emigrants.

Iron

Hey too...  Yeah, enjoying a mild winter here, too!

Iron

here in California is "pretty" cold too, 44ºF...

Iron

hi all --- winter heatwave in the 50's (today only) in the midwest, tomorrow back to 30's

Iron

wood is OK, you get warm twice, once when chopping, second when burning ;-)

Iron

Hey, you got summer down there!

I'm glad that the weather is warmly enjoyable even in southern Brazil. 

#1 and kerosene gells at about -60. So the residents of Alakaket and Huslia were going back to using wood stoves and burying their fuel tanks and lines with snow to bring the fuel temp up a little.

sounds like the movie "day after tomorrow"

Iron

@Alaskaman66: My diesel truck here in New Mexico won't start below 0F.  Kerosene is a little better but diesel turns to jelly at those temperatures.

 

Iron

These temps were in Farenheit, and that's actual temperature, not wind chill.

@Alaskaman66: Send some of it our way (Philadelphia). It's unseasonably hot here; we could use a couple of snow days!

Iron

The two temp graphs cross at -40. So -40 Celsius = -40 Farenheit

wow, forget about the groundhogs being out tomorrow! -70!!! doesn't even matter C or F!

Iron

@Alaskaman66: at some point asking if you mean C or F doesn't amtter. It's just plain cold. :-)

Good morning, all. FYI: some towns along the Yikon saw temperatures to -70 this week. All the kerosene stoves quit working

ready for another great session today.

Iron

Good afternon everyone

Iron

Be sure to click 'Today's Slide Deck' under Special Educational Materials above right to download the PowerPoint for today's session.

Blogger

The streaming audio player will appear on this web page when the show starts at 2pm eastern today. Note however that some companies block live audio streams. If when the show starts you don't hear any audio, try refreshing your browser.

 

Blogger

Good afternoon.

At what time do you start today?

Iron

Link tested and ready...Standing by...

Iron


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