Data transfer LinuxCNC to / from custom board - Solved

Just one thing to consider a USB connected device is not “realtime” and is at the mercy of all the delays, latency and disconnection and reconnection that comes with it.
Where as the 7i73 is realtime, rock solid and I’ve never seen it lose a connection.
Another great thing is due to the use of Cat5 cable for connection it can be mounted anywhere.
Unless you design your device to use native USB, which I can only recall one project that did ie: it enumerates as a HID device, you’ll basically be operating at serial port speeds rather than 2.5M bits a second. This may not be an issue depending on packet size.

Basically what it boils down to a 7i73 pendant is going to be more responsive than a USB based one.

Now there is always the possibility of implementing the smart serial protocol into your device.

Good points. I did a reality check on responsiveness by setting jog increment to 0.001" and then banged in 10 moves as fast as I could and it caught all 10, so faster than me.

I'm not ruling out the 7i73, one option would be to buy one and then remove the chip and solder it to my board I don't need the other stuff on the board, or perhaps Mesa will sell me just the chip? This approach still looks a little messy because the data from the touchscreen also needs to make its way to the 7i73.

Earlier (IIRC) (EDIT you  actually it was spumco) provided a link to an ArduinoConnect project. This is another possible solution I watched the video and thought hmmm this might just work? So pulled a little Nano out of the smorgasbord of wires etc on my bench and perhaps 20 minutes later it was hooked up to my Linux machine and visible in HAL configuration however when I manipulated the one input and output it did not work. I will try and find some time today to see if I can get it working. From my really quick perusal of the code other than the 5 s heartbeat it's static unless something changes so hopefully low burden and hopefully responsive enough.

I made a quick list of things I want to get from Linux back to my board and it's really not much (from memory)
Mode: jog, MDI, gcode running = 2 bits
Status: Estop, machine power, spindle on = 3 bits
Limit switches: = 6 bits or 3 if I code them
Rates: jog, feed = 8 bits each.

I don't have a sense of how much Linux time will be required for the .py code used for the HAL interface to deal with a small amount of data like this? I will need to learn about Linux tools for evaluating timing and burden. Bored in retirement ya.... sure;-)

This might be interesting, no src code but hex files to program 32 bit MicroChip MCU.

github.com/talla83/tshw

Well thanks to spumco for providing this link...
spumco post=294853 userid=28776

github.com/AlexmagToast/LinuxCNC_ArduinoConnector

I now have a little nano board communicating with HAL both inputs and outputs. So I just need to port the communication code from the nano test board into my ARM project and rejig the messages a bit and with a touch of luck I should have bidirectional data flow from HAL to my board. Hopefully the .py script is easy on the Linux overhead.

slowpoke wrote:

Well thanks to spumco for providing this link...
spumco post=294853 userid=28776

github.com/AlexmagToast/LinuxCNC_ArduinoConnector

I now have a little nano board communicating with HAL both inputs and outputs. So I just need to port the communication code from the nano test board into my ARM project and rejig the messages a bit and with a touch of luck I should have bidirectional data flow from HAL to my board. Hopefully the .py script is easy on the Linux overhead.
 

ArduinoConnector has major issues that the author does not seem to want to fix as they've been working on a V2 branch. The last commit was my friend fixing a bug I found before I dropped it. I wasted alot of time with ArduinoConnector, I made 2 custom PCBs around it just to realize it had so much lag it was unuseable (see my git issue).

Maybe version 2 will be better, but the main branch can't handle an MPG. You will wait literally 10 seconds for it to count the pulses and relay them back to LinuxCNC. All the lag comes from the Python side, the MCU side is fine. It's a great idea, with some great features. Unfortunately it's currently unusable unless you just want to push a couple of buttons.

andypugh wrote:

I knew there was another HAL component that might be relevant, I don't know how I missed it:

linuxcnc.org/docs/stable/html/man/man1/sendkeys.1.html
 

 

Andy,

I need some clarity on a few points for sendkeys.

At this point I have an Arduino board that can trigger events in halshow, So when I activate an Arduino connected push button, the jog-x-pos and the halui.axis.x.plus changes from yellow to red. I expect the actual X-axis to jog when I press that button, however other than the yellow to red indication nothing happens. (the system is NOT in Estop, and the machine is enabled on the manual control tab. If I mouse click on the "+" button, the x axis does jog.

Do I need to enable/invoke SENDKEYS, to actually get the yellow to red indication of jog-x-pos to do something?

Assuming that I do need to enable SENDKEYS, I need a little help with a few points in the SENDKEYS documentation.
 Instructions say "Create a new entry in .B/etc/udev/rules.d/99-input.rules"

I'm not sure where ".B" is?

I did find       /etc/udev/rules.d/70-persistent-cd.rules
So neglecting the missing ".B"  I assumed this is the file I'm supposed to update?
However when I add "sudo echo KERNEL=="uinput", GROUP="uinput", MODE:="0660" | sudo tee /etc/udev/rules.d/70-persistent-cd.rules" to that file I get the attached error message. So lots of possible mistakes here: wrong location, wrong file, adding the uinput group did not work even though it seemed to (see last attachment) the discrepancy between 99-input.rules ,77-persistant-cd.rules , 88-input.rules?

Please advise.
 

 
 

Aciera wrote:

Note that 'halui.axis.jog-speed' needs to be set for plus minus jogging: 

linuxcnc.org/docs/html/man/man1/halui.1.html

Thanks for that, however setting halui.axis.x.plus did not help.
When I press the Arduino button, the jog-x-pos and the halui.axis.x.plus indicators both change from yellow to red. For some reason they don't trigger an actual jog.