On Fri, Nov 06, 2015 at 08:28:48PM -0500, Neil wrote:
>=20
> On 11/6/2015 7:07 PM, James Cameron wrote:
> > I'm puzzled at this. While the underlying parts of a system may have=20
> > real-time requirements, there doesn't seem to be much need to extend=20
> > the real-time design process all the way up to the human interface,=20
> > unless you're dealing with split second decisions, such as playing a=20
> > musical instrument or rocketry range safety controls. The=20
> > garbage-collected languages have a wider standard deviation of=20
> > latency, but they can still be characterised and described. If you=20
> > need to infect the rest of the system with the real-time moniker,=20
> > don't forget the underlying operating system.=20
>=20
>=20
> A few years ago, I was using Java on Android to receive serial data=20
> (over bluetooth) from a PIC-based circuit.  I can't remember the specs,=20
> but pretty sure it was only under 100 bytes per second. Simple app that=20
> read the incoming data and put it on the screen.  It was very=20
> problematic, dropping bytes regularly.  I had an experienced app=20
> developer at the time who was working with me on this, and he chalked it=
=20
> up to be a limitation of Java.  Others also suggested I should instead=20
> use the NDK for that type of app.  This will be a big part of what I'm=20
> doing -- receiving continuous test data from embedded projects -- but on=
=20
> a PC this time, and can't see how Java would be much better on a PC.  I=20
> agree, the OS is a also a potential problem, but I'm somewhat stuck with=
=20
> that (as that's what my customers have), and I expect most average PC's=20
> would have more than enough HP to handle this.  So maybe I don't need=20
> full real-time, but definitely better than the Java I know.

Hmm, thanks.  To me that sounds like a Bluetooth card, driver, or
stack problem, and it should be isolated by using something other than
a Java app, something like busybox's cat on the Android debugging
console.

The Java app can then be isolated by feeding it simulated data some
other way.

I've never heard of Java, in and of itself, missing data at that kind
of low rate.

--=20
James Cameron
http://quozl.linux.org.au/
--=20
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