Realtime feed rate for THC

[Francois-le-francais-dev]

I plan to use the actual feed rate (real time) to fine tune my THC.
I run GrblHAL on a T41E5XBB board from Ph. Barrett.
I want to use I2C to send it to my MEGA 2560 THC at 20 Hz frequency or more. Serial could be an other choice but not my question for now.

I made some working code (with AI help !) but it always lead to errors in the sender (bCNC, ioSender, etc.), code errors 1, 2, 25, etc. (gcode syntax pb caused by communication issue I suppose).
I think it's caused by ISR usage but my understading is lost in GrblHAL code structure and hook functions usage.

I tried to use :
1/ st_get_realtime_rate();
2/ stepper->exec_segment->current_rate;

Any advice to implement this trivial plugin ?

Here is a video of a working test of R03 plugin attached :
https://drive.google.com/file/d/1qO-Ugua_VGeInPjc2vxdHsw699LDRHlS/view?usp=drive_link

Many thanks for your kind help.

P.S. files attachement refused (CPP, C, H) so I converted to txt ;o)
my_plugin_c_R03.txt
my_plugin.txt

[Francois-le-francais-dev]

Complement files :
feedrate_i2c_wrapper_cpp.txt
feedrate_i2c_wrapper_h.txt

[terjeio]

1. Do not hook into grbl.on_realtime_report, per default this is called on demand from the sender. Use task_add_delayed() instead for repetitive task running slower than once per ms.

void my_task (void *data)
{
     task_add_delayed(my_task, NULL, 20); // reschedule

     ..do stuff....
}

void my_plugin_init(void) {

   ...init code...

    task_run_on_startup(my_task, NULL); // Start the show after startup completed
}

2. Do not call Arduino I2C code unless you are sure it does not block or interfere with the driver implementation. It is better to call the driver implementation. In addition this is portable between drivers. Some plugins are already using this API.

3. Tip: to convert the machine state from flags to sequential numbers use ffs( state_get()), this returns these values.

[Francois-le-francais-dev]

Compilation ok but the sender fails to open COM port.

my_plugin_c_R04.txt
errlog_bCNC.txt

[terjeio]

You have to ensure the I2C API is up and it is a good habit to probe the external device and not start polling unless present. An example.

And I suggest you use non-blocking transfers by setting the last parameter to i2c_send() to false, if there are no ongoing transfers the call will then return immediately after buffering the data. Or do you have to wait for the transfer to finish?

[Francois-le-francais-dev]

After numerous attempts, the I2C API never connected, so I gave up and went back to the Arduino code that works well with my board.
I will try to understand Keyboard I2C plugin example and test it again later.

So the plugin works great up to a 2 ms delay that is the fastest I tested !
It is now configurated at 10 ms delay that is the same as the default ACCELERATION_TIPS_PER_SECOND 100 GrblHAL conf.
It fits my Teensy based T41E5XBB board.

I'm so glad to have this new perfect tool to investigate THC control.
It is so useful to better understand Grbl motion control and what really happen when you do plasma cutting !

Ok, the code isn't very professional, but maybe it can serve as a basis for some other project.

Now I have to integrate the use of it in my DIY fast THC and to see if it can lead to a higher level my DIY plasma fast cutting CNC !
Yes I leave in a fast DIY world ;;;)))

If you have any remark or suggestion I will be pleased to read you again.

Thank you so much.
François

my_plugin_c_R05.txt

[Francois-le-francais-dev]

Arduino receiver code
feedrate_I2C_receiver_ino.txt