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I hope this message finds you well. I am currently trying to install LinuxCNC on a Raspberry Pi Zero 2 W for a course requirement. Unfortunately, most of the installation guides I have found online are outdated.The Raspberry Pi's current system version is Debian 11 Bullseye. I have successfully applied real-time patches to the Raspberry Pi, and the system version is as follows:
Linux raspberrypi 6.1.74-rt13-v7 #1 SMP PREEMPT_RT Thu Feb 29 16:17:14 CST 2024 armv7l GNU/Linux.My main issue arises when following the official LinuxCNC build instructions. When I use dpkg-checkbuilddeps, it prompts me with the following error: "dpkg-checkbuilddeps: error: Unmet build dependencies: dh-python python-lxml." However, when I try to install these two packages, I receive an error indicating that the packages cannot be located. I have tried several methods to resolve this issue but have been unsuccessful.I would greatly appreciate any assistance or guidance you can provide on how to resolve this issue. Thank you very much for your time and support.Best regards

rodw wrote:

I can't help you with as I don't have the hardware. But I can put you on the right track!.
Homing is managed in Linuxcnc by homing.c
github.com/LinuxCNC/linuxcnc/blob/master.../emc/motion/homing.c

Master branch has recently released the homecomp.comp compoonent
linuxcnc.org/docs/devel/html/man/man9/homecomp.9.html
and the source file here github.com/LinuxCNC/linuxcnc/blob/master...onents/homecomp.comp
The purpose of homecomp is to give a method to override homing.c behaviour to build a custom homing behaivour

You should also look at Domminic Braun's ethercat cia402.comp and supporting hal file github.com/dbraun1981/hal-cia402
which predates homecomp and also attempts to deal with hardware which homes externally. He also deals with the conversion of motion units between Linuxcnc and external hardware. Look at how he uses read and write functions. This might be able to be done in halcomp as there are procedures that read all pins and writes all pins.
Your homecomp needs to be able to deal with following errors that will ocur when the extenral drives move without lcnc's knowledge. This can be done by equating the feedback position with current position during external homing.
There are a large number of homing states that can be skipped or ignored when external homing is done so you homecomp basically just needs to initiate homing and wait intil homing is completed ,Tell Linuxcnc you are homed, and then let Linuxcnc continue on.

God luck with this, its complex because in a homecomp, you need to deal with all joints at a time where a component like cia402.comp has a seperate instance of the component for each drive being homed...
 
 

some time left after that - but i continued working on that. firs a short update on current status:

-> for homing 2.9+ is necessary (took some time that i recognized that i was still on 2.8. on my raspberry)
-> on my Raspberry the user COMP does not work on 2.9.2 (first i tried the bookworm image of dec23, and also tried to run on Buster with manual install based on instruction and froum thread)
-> anyway my pokeys.comp seems to work fine on a laptop using the "linuxcnc_2.9.2-amd64.hybrid.iso"
-< for the problems due to not yet created pins when halfile tries to write on them, i created two dummy components that add some millisecond delay during loading of Hal (e.g. loadusr -W start_delay_5000), these use the extra_setup option during start to wait for 5000 ms or 3000 ms.

i created a first version of pokeys_homecomp.comp. As pokeys.comp itself is userspace and the homecomp is RT, as a first step the homecomp is a dummy, which receives the hal-commands and routes it to the pokeys.comp using pins and signals.
-> it seems to compile fine BUT when i try to load that in [EMCMOT]HOMEMOD=pokeys_homecomp i get a cyclic errors like "USRMOT: ERROR: command timeout", so i added some debugmessages in hope that it helps to find out which function is causing that.
-> so far no idea yet.

on a second path i try to get that poKeysLib usable in a RT. Currently it compiles and EMC was starting but it did not show up in HALMonitor. But since i added references & calls for PokeysLib i get a "undefined symbols" when i try to start a hal that contains that comp.
-> here i assume that pokeyslib is not yet ready to run on RT (i assume because lubusb1.0) so i started to create a copy of that H file which excludes that (using the #undef POKEYSLIB_USE_LIBUSB), but it seems that there's more work on that to do.

You would be better off looking for debian packaged VNC software here packages.debian.org/index
It will tell you if there are ARM64 packages but the way debian works, it builds for all platforms 

Rods tool chain creates a Debian based image, not a Raspberry Pi OS based image. Whilst the are similar there are some differences, you lose some of the customizations that Raspberry Pi Foundation has.
On my Raspberry Pi based image I used this tutorial:
pimylifeup.com/raspberry-pi-vnc-server/

Can't remember if I checked latency, if I did it doesn't stick in my mind there were any latency issues. One thing I forgot to add is I changed from the wayland backend to the X11 backend using raspi-config. The X11 layer in wayland was very very slow in some of the tests I tried.

just a brief status of my experiments...

I spent several days trying to setup the feasible VNC server on the Debian 12 LinuxCNC image but unfortunately looks like I can't. The only successful result was reached with x11vnc, but jitter grew up to ~280 μs (280,000 ns) just after I run x11vnc process (even with no connections).

I also tried to install there wayvnc like on raspberry OS, but debian sources contains too old version 0.5xx. On raspberry it is 0.8xx RC and several days ago they released regular 0.8. But I didn't understand how to resolve the dependency hell with all the required packages...

Will try to use Rod's toolchain to prepare the image based on the Raspberry Pi OS — I'm really loved in the way how can I customize all the required packages and appearance before the image has been flashed.

If someone resolved the lightsweight enough VNC server on Debian, I would be pleased to take a look. Thanks,

1, You can wire the drives with either
common ground:
= drive step-/dir- --> GND,  BOB step/dir --> drive step+,dir+
or common +5V:
= drive step+,dir+ --> 5V, BOB step/dir --> drive step-,dir-

If you use common 5V, you must invert the step outputs
as they are now active low

Typically you would not use an axis for the spindle


 

Regarding the Sain Smart 5-Axis CNC Break Out Boards (ST-V3)  and lathe spindle, is the A axis used for the spindle?  Or is that somehow configured in LinuxCNC?

I have received the two Sain Smart 5-Axis CNC Break Out Boards (ST-V3) which connected easily to the Mesa 7C81. 

When I connect these BOBs to the StepperOnline DM542T drivers, it seems that the common connection is +5V, not GND.  Does it seem right that it would be connected this way?

BOB                    DM542T
+5V                      PULse +
                             ENAble +
                             DIRection +

ENable                ENAble -

DIRection           DIRection -

STEP                    PULse -

I'm another with a KMB-I. Mine is 1981 B control, and is fully functional as is. Pretty much original. Parajust VFD, ServoMate ±12V signal Servo boards and has the same Electro-craft 90volt brushed motors with built in tachos and Litton 200 cpr quadrature encoders almost as described here. forum.linuxcnc.org/12-milling/39662-hurc...s-cnc-update?start=0  It has the Bristol Erickson quick change #30 spindle. Oh yes, I do also have Buddy Maughon's tape emulator. It had stood unused in a private workshop from 2001 to 2021. Had to replace a variety of electronic pieces in the control and parajust to get it to start and run, six month entertainment, prodding with a scope and voltmeter, but worth is as only run for 1938 hours, so straight and true. Oiler, spindle, brake safety pressure switch coolant systems, flood and mist etc all in good order.

My requirement is 'only' that I want to be able to send it some G-code so I can machine some weird 3D shapes.
So, I'd like to be able to swap to a Linuxcnc front end, but in a way I could perhaps swap back to the conversational system I have come to admire and like. I guess in one dream, maybe a Hurco conversational front end could be built for linuxcnc...
Yes, I know the obvious solution would be a B to BX controller upgrade. Would I think do all I need, but the current price is so much more than what I paid for the whole machine, I'm having a hard time justifying that kind of expenditure.

So, I've a running linuxcnc 2.9.2 app as well as mesact installed on a Raspberry PI-5 and a 7i95T ethernet on order from JT, too many axes I know, I am also aware the the three shaft encoders will need more pulses, and can handle that as have already fitted one USdigital item to deal with the Y encoder that had a chip out of the glass scale and several lines missing. The USD part needed a mounting base making, but otherwise worked straight out of the box. 
But then I kind of missed the point with all the daughter board options, and I would appreciate some clear sighted and informed opinions on which ones I really need to make this dream a possibility. 7i77 or 7i83 for instance might be ok for the servos, but then they've 10V versus 12V output that the ServoMate is expecting. Secondly I probably also need maybe a 7i73 to interface with any jog generator and buttons on the panel.

Apologies for writing so much, but I'm hoping that the detail will be helpful to someone some day.

Fingers crossed.

If you type sudo menu-config, you should be able to edit your username and password and other settings in a graphical environment. Refer the screen dump in the read.me on my repo.

There is a script mentioned on tthe qtplasmac docs page for installing QT. Maybe find it and give it a try

I installed the kernel using packages & info here
github.com/kdoren/linux/wiki/Installatio...ge-(Raspberry-Pi-OS)

then I used the following to prevent the kernel being upgraded
sudo apt-mark hold linux-image
sudo apt-mark hold linux-headers

reboot
used this
www.linuxcnc.org/linuxcnc-install.sh

then installed linuxcnc-uspace-dev

Seemed to work fine

you probably need to run the daemon before qt, its probably in start menu

Thank you cornholio and rodw for your answers!
- About the SD Card and I decided to think that it was some troubles with SD partition and just taken another one, if it will be reproduced - I'll dig it deeper.

- I understand the idea of selecting kernel-and-patch consistency, in my actual test I try to take fresh kernel 6.1.77 and corresponding RT patch 77-rt24.

I also excited about the way of installing additional packages from standard Debian sources as well as from additional using userscripts.

rodw, I also would suggest a small fix to support the spaces in full name, otherwise someone will receive something like that (example for full name "Andrey CNC"):
+ adduser ago --gecos Andrey CNC --disabled-password
adduser: The user `ago' does not exist.

As I understand it is placed in two places:
* github.com/rodw-au/rpi-img-builder-lcnc/...ccount#L12C29-L12C36
* github.com/rodw-au/rpi-img-builder-lcnc/.../scripts/stage2#L112
(Not sure about the correct fix, I am not very experienced with bash yet. I tried to fix it with '${NAME}' but just received name ${NAME}
I am very excited to the way you did this image builder!

cornholio, you said that you did something similar to my experiment with the original Raspberry Pi OS image. I slightly confused with my tutorial at the early beginning of this thread. Nevertheless I did it once, I can not repeat it anymore... Not sure what the problem is, unfortunately screen shows very fast several red lines in the console during the boot and then I see the only black screen. Did you posted your steps somewhere? I I will be very pleased if you could briefly take a look at my solution and find problems there if any.