#linuxcnc-devel Logs

Nov 27 2017

09:26 AM pcw_home: andypugh: The discovery protocol supports up to 256 bytes, currently there are a few limits to FPGA size: UART FIFOs use SRL16s for efficiency
09:27 AM pcw_home: so 16 bytes maximum (-status and CRC) so this limits user data to 14 bytes (now 3x32bits = 12 bytes max)
09:27 AM pcw_home: on Spartan6 chips you have SRL32s available so you could roughly double the user data without a huge FPGA resource hit but this would require
09:27 AM pcw_home: Spartan6(7) only and more RAM also since each channel has RAM RX and TX buffers, I would have to check where we are with RAM
09:53 AM jepler: this is apropos of nothing, but I was reading about i2s audio and thinking about how you could get about 44 channels of audio from one 50-pin connector (a shared clock, a shared "word select", and 22 data channels each carrying 2 audio channels). There's got to be somebody out there who needs this product, right?
10:11 AM pcw_home: I think theres some kind of RS-485 Audio distribution system that theatres use (may be replaced by Ethernet nowadays)
03:20 PM jepler: it is better to marry than to burn with passion.
03:20 PM jepler: oops
03:22 PM jepler: I meant to paste this: https://mastodon.social/@JoeOsborn/99078363089955504
04:55 PM andypugh: I wonder how crazy it is to try to make a state machine with nested loops in it. One that continues the nested loops on re-entry.
04:55 PM andypugh: I am trying to make a thread-safe way to iterate through an array of items.
04:56 PM andypugh: (where the items might need attention that takes too long to run inside the servo thread)
04:57 PM andypugh: static int i;
04:57 PM andypugh: for ( ; i < max; i++){
04:57 PM andypugh: That wiil probably work, won’t it?
04:58 PM Tom_L: syntax looks ok
04:58 PM Tom_L: why the
04:58 PM Tom_L: ; before the i though?
04:59 PM andypugh: I thought you needed one.
04:59 PM Tom_L: c? or something else?
05:00 PM seb_kuzminsky: yes you need it
05:00 PM seb_kuzminsky: the for() statement in c takes three expressions: initializer; conditional; increment
05:01 PM seb_kuzminsky: in this case the initializer is empty, but you still need the ; to indicate the empty statement
05:01 PM andypugh: When I sat down here I thought that this idea would be hard to imlement, but now I suspect that it won’t.
05:01 PM andypugh: Though I will write a test-case first.
05:05 PM seb_kuzminsky: just make sure i gets set *somewhere*
05:19 PM jepler: andypugh: if it's something that can be related to multiple instances, then probably relate it to instance data instead of as a static. we already had one apparent bug like that in hostmot2. https://github.com/LinuxCNC/linuxcnc/issues/343
05:23 PM andypugh: Very good point.
05:24 PM andypugh: Yes, it would potentially all go a bit wrong with mutiple sserial ports
05:24 PM skunkworks_: seb_kuzminsky, I ran zultrons limit3 all weekend with no surprises...
05:25 PM seb_kuzminsky: skunkworks_: wow, that's great
06:23 PM Roguish: hey all. is there a way to find a particular post in the forum given the post number?
06:25 PM Roguish: got it. google to the rescue.
06:43 PM andypugh: You can just click on any post and then edit the url to the number you want
06:44 PM andypugh: Hmm, or maybe you can’t
06:45 PM andypugh: Sorry, that doesn’t actually seem to work.
08:37 PM jepler: it seems you have to also know the number of the sub-forum
08:38 PM jepler: ugh mentioning the forum made me check. kunena minor update incoming. let's hope there are no earth-shattering kabooms.
08:53 PM jepler: OK so the direct link to a topic by topic number is https://forum.linuxcnc.org/topic?id=286 -- the direct link to a post by post number is https://forum.linuxcnc.org/topic?mesid=346#346
08:53 PM jepler: roguish: ^ not that you'll see this