How to enable the velocity ramp running in the TMC-Eval FW from pytrinamic ?

[marlesus]

Hi there,

I am tryting to enable the velocity ramp option that is available within the Position Mode from TMCL-IDE. Can you please tell me how can I do this using the pytrinamic ? Do you have an example of code snippet for this ?

Thank you very much for your time!

Best regards, Paul

[trinamic-bp]

Hi Paul, Could you tell us what eval board you are using. I guess then it is easier for us to help you.

BR Benjamin

[marlesus]

Hi Benjamin,

Oh, sorry, I forgot to specify this. I am using the TMC4671 Eval board with a BLDC motor & ABN Encoder.

Best, Paul

[trinamic-bp]

Code examples for the TMC4671-EVAL can be found under examples/evalboards/TMC4671. But I think the examples only cover torque mode. Not sure what the "enable velocity ramp option" in the TMCL-IDE is about, I'll take a look at it.

[trinamic-bp]

I think I got it now. The firmware on the Ladungsbruecke implements this ramp. The firmware maybe does its own position control and is feeding the PID_VELOCITY_TARGET, not sure though. This functionality is configured and controlled via a higher level (parameter) interface to the Landungsbruecke . The PyTrinamic examples only operate on pure register-level. Technically PyTrinamic could also talk to the firmware on the Landungsbruecke via this higher level interface, but I'm not sure if you really want that? I guess important takeaway is that this position/velocity ramp is not implemented in the TMC4671 chip itself.

[marlesus]

Hi Benjamin,

yes, that‘s exactly what I would like to achieve: enable and use the velocity ramp (which is done by simply ticking a checkbox in the Position Mode window from TMCL-IDE) from python using the PyTrinamic libraries… So, there is no example on how to do that? It‘s a pity… This is really a useful feature, as it limits the acceleration and avoids the unwanted bumps especially when starting a move… But there‘s no way on how you can guide me to enable this velocity ramping from PyTrinamic ?

Best regards, Paul

[trinamic-bp]

We are trying to create you an example. It will probably be something like this.

with ConnectionManager().connect() as my_interface:

    # Create TMC4671-EVAL and TMC6100-EVAL class which communicate over the Landungsbrücke via TMCL
    mc_eval = TMC4671_eval(my_interface)
    drv_eval = TMC6100_eval(my_interface)

    ... # lots of mc_eval.write_register()

    my_interface.set_axis_parameter(12, 0, 1)

Via the set_axis_parameter() function we can access the "higher level parameters" I was talking about before. But yeah, a real example is coming.

[marlesus]

Hi Benjamin,

Thank you very much! Much appreciated.

Best regards, Paul

[trinamic-bp]

Hi Paul, we added a new example: examples/evalboards/TMC4671/TMC4671_eval_TMC6100_eval_BLDC_ABN_encoder_position_mode_linear_ramp.py I hope you can make sens of it. In line 98 to 100 the ramp settings are updated.

Please note that you will also need to update to the latest PyTrinamic version (0.2.6), we did a few updates there.