How to delay until a next increment of time occurs ?

[Gene Heskett]

On Thursday 14 November 2019 13:05:06 Dennis Lee Bieber wrote:

> On Thu, 14 Nov 2019 09:31:34 +0100, "R.Wieser" <address at not.available>
>
> declaimed the following:
> >What I tried to indicate is that the Pi has 500,000 cycles to work
> > with between two of those time events.   I consider that to be quite
> > a few.
>
> 	But the ARM instruction set is not a 1:1 with clock cycles. Loading
> the program counter (in effect, jumps and subroutine calls) takes 5
> cycles on an older ARM 9 core. ARM apparently no longer provides
> instruction cycle data for processors (and suggests one should use
> performance counters to profile sections of code).
>
> 	And then one needs to take into account that Python is a byte-code
> interpreted language, wherein an instruction may invoke whole
> subroutines of native code.
>
> 	The R-Pi has never, to my knowledge, been billed as suitable for
> industrial/real-time/process-control... It was billed as a device for
> learning -- using Python and simple digital GPIO. The newer ones are
> getting closer to serving as a general desktop computer.
>
Gee I hate to burst your bubble Dennis, but I am currently running a 
cnc'd, 70 yo, 1500 lb, Sheldon 11x54 lathe with a 2GB rpi4. And if it 
wasn't for the cost of changing the interfaces, I am considering 
replacing all my intel stuff running 3 more such machines, with rpi4's. 
The pi's all use an spi interface running at several tens of megabites a 
second, where the wintels are using some variation of the old parport at 
about 5 mb/sec. I think its called progress. But at 85 the grim reaper 
has come calling twice, and blinked twice. I'll get a new aortic valve 
in December, which should lengthen my visit here, but who knows for 
sure?
>
>
> --
> 	Wulfraed                 Dennis Lee Bieber         AF6VN
> 	wlfraed at ix.netcom.com    http://wlfraed.microdiversity.freeddns.org/


Cheers, Gene Heskett
-- 
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page <http://geneslinuxbox.net:6309/gene>