Although Linux is not realtime, you may still be able to do what you
want, depending on the latency required to *react* to the pulses.
You can write an IRQ handler, which should be able to count pulses
accurately if there're not coming too quickly. I don't know what the
lower bound (I.e. What is too quick) would be, so that's probably worth
investigating.
From there, your app can read from the IRQ driver how many pulses. The
app is going to have latency, but you might not care about it there.
--Andy Gryc
On Wed, 30 Mar 2005 11:54 am, zliminator wrote:
> Thanks for your reply. Too bad, I was kinda looking forward to learning
> Linux. Now I'm wondering if there's any other OS that would work on
> this board that would be more suited to as an RTOS. Also, I seemed to
> remember seeing a flavor of Linux that was supposed to be RT. I'll have
> to do some research on google.
>
> Dan
> Ricardo Wiggers <> wrote:
>
>> zliminator escreveu:
>>> I want to use the TS-7200 for counting pulses from 1 or more
>>> hall-effect switches to determine wheel speed. I also want to read a
>>> keypad, display results on an LCD and so on. I remember trying this
>>> with either a 2800 (slow) or a 5300 from Technologic using DOS/uCos
>>> and it seemed to bog down. I'm wondering if the 7200 running Linux
>>> will be fast enough without having to come up with auxilary hardware
>>> like a PIC which reads the pulses and calculates the wheel speed and
>>> sends the info to the 7200 in an sync serial format (a lot of work and
>>> more to go wrong). Also, would Linux be the choice for a realtime app
>>> like this? This is meant for a car and will probably only read 2
>>> hall-eff switches to determine MPH and pulses from the coil to
>>> determine RPM. The reason I'm reading 2 hall-eff switches is to detect
>>> for wheel spin.
>>>
>>> Dan
>> Hi!
>> Linux is no realtime system. The RTAI port for TS7200 is going on, but
>> is far from ready. Reading pulses is a trivial task for a PLD or uC,
>> and
>> it seems a better option to count the pulses there and read it and
>> process int the SBC, but you app seems to me (from the vague
>> description
>> above) more suited to be entirely done in a uC.
>> Ricardo
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http://gryc.ws
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