Re: missed keystrokes problem, back with a vengeance.
On Sun, 2017-01-29 at 13:10 -0500, Gene Heskett wrote:
> On Sunday 29 January 2017 12:16:52 Jonathan Wilson wrote:
>
> > On Sun, 2017-01-29 at 08:47 -0500, Gene Heskett wrote:
> > > Greetings everybody;
> > >
> > > I am in the process of bringing a nearly 70 yo Sheldon lathe back to
> > > life, useing an raspberry-pi 3b for the machine controller.
> > >
> > > However, I have now had 5 different keyboards plugged into it, some
> > > wired, some wireless, and none of them can give me a dependable
> > > response to a key, and the error seems much worse for the key-up
> > > event. When driving the machine by hand as we often do for one-offs,
> > > missing a keyup event can be disastrous for the part being made
> > > because it keeps on cutting until you've given that, or another key,
> > > a quick tap to stop the unwanted motion.
> >
> > I'm wondering if the problem is noise on the power, or RFI noise being
> > picked up/interfering with the usb cable and/or PI in general. I'm
> > guessing that the lathe is probably kicking out a shed load of RF
> > noise into the air or on to the power line and the pi is not overly
> > hardened for such a harsh environment.
>
> Understatement of the month... :)
:-) Its a good old British tradition to always understate ;-)
> This application, linuxcnc, is largely written in python, but I'm not fam
> enough with python to go mucking about in its internals. And the fact
> that 3 other installations of the same code on x86 boxes do not have
> this problem tends to point a pretty stiff finger at the pi.
Yeah, the PI is made down to a price point (Although I'm fairly sure it
meets some CE requirements:
https://www.element14.com/community/docs/DOC-43262/l/updated-29-march-frequently-asked-questions-about-raspberry-pi but it may be that any standards regarding "input noise", as opposed to it generating RFI, are possibly not met, likewise input shielding, de-coupling, etc.) ... X86 boards not only have to meet Intel standards but also a host of International and US standards and I'm guessing that some of the standards, either international or Intel, exceed the minimum legal/ISO/CE requirements (for being able to sell into markets) when taken as a whole.
>
> > > There is something funkity in the usb keyboard handling that can get
> > > much worse with a reboot, or get almost perfect with a reboot.
> > >
> > > Its all uptodate a/o yesterday. The psu is a 4 amp box, making 5.07
> > > volts solidly. Verified with a 100 Mhz scope.
> > >
> > > What can I do to fix this?
> > >
> > > Cheers, Gene Heskett
>
> Thank you. There might be the seeds of a fix in this.
You're welcome.
>
> Cheers, Gene Heskett
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