As for baremetal RTOSes, I usually find that ChibiOS is quite good. It has
very good support for the STM32 (including the F4) and it already comes
with a HAL.
2014-09-07 16:01 GMT-03:00 Gullik Webjörn <[email protected]>:
> I saw the STM32F429 Discovery kit, a little bit more cpu, 64 Mb ram,
> a TFTP display so could display the constellation, at about € 20.
>
> Who is the first to port to that board?
>
> G
>
> On 08/21/2014 12:29 AM, glen english wrote:
> > Nice work David.
> > Maybe some one can let me know what the scope of topics of this forum
> > is. Hopefully, forum users will accept this brief off topic discussion.
> > I apologize in advance.
> >
> > Agreed with all on development cost. Depends on the market I guess. The
> > STM32 is actually right at the high end of complexities for the MCU
> > market. It is a complex device. But effective.
> >
> > From my aristocratic POV, 60mA at 3V is a real power hog for a battery
> > device, but- as you say David - IT MEETS THE OBJECTIVES , and that is
> > really what it is all about . Something either meets objectives, or it
> > doesn't . Anything else is just fluff.
> >
> > For a box that does not have to do much- simple sequential processing,
> > IE convert ADC, filter microphone samples- encode audio - add framing
> > bits - generate modulator samples, a simple interrupt driven job is fine.
> >
> > Now, throw in a bunch of asynchronous peripherals, peripherals that
> > must be talked to loaded with data, waited up for events to finish and
> > now you have a real problem with the sequential system, and the simple
> > kernel that provides waitable semaphores and timers and some basic co
> > operative multitasking is the answer, rather than a complex state
> > machine. And a basic kernel will only cost less than 100 cycles on a
> > context switch. In 2000 I wrote basic kernel for the AVR that did a
> > context switch in about 60 cycles. So, OS need not have much overhead,
> > and it is ideal when different people are writing for different
> > jobs/peripherals on the one chip.
> >
> > glen english
> > VK1XX
> > "yes - I do this for a living"
> > Altium- ModelSim, Matlab, Vivado, Rowley.
> >
> >
> >
> > On 21/08/2014 8:12 AM, David Rowe wrote:
> >> Hello Glen,
> >>
> >> Yes I agree re the STM32F4's DSP capability. It doesn't have proper
> >> single cycle MACs. However it's fast and cheap and has float so it does
> >> the job nicely. Curiously, no operating system ends up being kinda
> >> helpful on a CPU of this size.
> >>
> >> I measured 60mA at 3V on the STM32F4, that's the lowest power CPU I have
> >> ever played with! I estimated 24 hours operation on a pair of AA's.
> >> Plenty.
> >>
> >> I think if I was doing a multi-channel FreeDV device I'd use .... a PC.
> >> Just throw MIPs at the problem. Dead easy to develop on. I/O would be
> >> the only hassle.
> >>
> >> Cheers,
> >>
> >> David
> >>
> >> On 21/08/14 07:27, glen english wrote:
> >>> indeed Bruce.
> >>>
> >>> Consider I might be aiming at a portable device, or other low power,
> low
> >>> count silicon platform. (5$)
> >>> and bear in mind, I might want a heap processing power left over for
> >>> modulator/demod, error correction, some audio processing , noise
> >>> reduction etc.
> >>>
> >>> For those that know real DSPs, they'll recognize that the Cortex M4
> >>> (stm32 4...) is NOT a real DSP. It has some handy instructions, they
> >>> call DSP, sure. But start throwing it alot of filtering tasks and
> you'll
> >>> run out of cycles.
> >>>
> >>> It is a very good general purpose processor though, excellent in fact.
> >>> I use it for all sorts of things when I don't care about power
> >>> consumption. The CODEC2 is not a simple DSP task, it is much more a
> >>> complex algorithm that doesnt get alot of help from a real DSP. The
> >>> STM32M4 is not a low power processor.
> >>> A real FP processor like the latest low power SHARCs ($10) for similar
> >>> money might do the job for less power, depending on the efficiency of
> >>> the coder- that's the thing to get the advantage of the real DSP, you
> >>> got to know what you are doing. The M4 will make fairly good throughput
> >>> out of junk coding. I use the Rowley Associates toolchain.
> >>>
> >>>
> >>> glen english
> >>> VK1XX
> >>> "yes - I do this for a living"
> >>> Altium- ModelSim, Matlab, Vivado, Rowley.
> >>>
> >>> On 21/08/2014 5:44 AM, Bruce Perens wrote:
> >>>> The reasoning is indeed that floating point is easier to develop and
> >>>> that our development time is more expensive than CPUs.We don't know
> >>>> the table sizes offhand.
> >>>>
> >>>> However, the assumption that both of the codec and modem would fit in
> >>>> really small and relatively low-power floating point chips was
> >>>> optimistic and as of this moment it's right on the edge of working in
> >>>> the STM32F405 that David has built into his SmartMic project. The
> >>>> STM32F405 is an ARM Cortex M4F at 168 MHz, 1 MB FLASH, 126K
> >>>> instruction/data RAM, and 64K data RAM.
> >>>>
> >>>> Over the past weeks David has torn through the code working on
> >>>> optimization, and at this moment the receive speed is "borderline".
> >>>>
> >>>> Thanks
> >>>>
> >>>> Bruce
> >>>>
> >>>> CPOn 08/20/2014 11:42 AM, Steve wrote:
> >>>>> I think the reasoning is, that floating point and memory are so cheap
> >>>>> now, that trying to fit a design into a restricted space would just
> >>>>> lengthen the time to profit.
> >>>>>
> >>>>> Why design to a fixed point $30 DSP when you can buy a $5 CPU with
> >>>>> hardware FP.
> >>>>>
> >>>>> 73,Steve
> >>>>>
> >>>>>
> >>>>>
> ------------------------------------------------------------------------------
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> >>>>> _______________________________________________
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> >>>>
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> >>>> _______________________________________________
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> >>> --
> >>> -
> >>> Glen English
> >>> RF Communications and Electronics Engineer
> >>>
> >>> CORTEX RF
> >>> &
> >>> Pacific Media Technologies Pty Ltd
> >>>
> >>> ABN 40 075 532 008
> >>>
> >>> PO Box 5231 Lyneham ACT 2602, Australia.
> >>> au mobile : +61 (0)418 975077
> >>>
> >>>
> >>>
> >>>
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