drivers: stepper: introduce rudimentary ramp control #88564

jilaypandya · 2025-04-13T19:25:49Z

Introduce rudimentary control using following paper:

https://www.boost.org/doc/libs/1_81_0/libs/safe_numerics/example/stepper-motor.pdf

Other References:
Equation 13 in the above mentioned paper can also be seen in this app note.
https://ww1.microchip.com/downloads/en/Appnotes/doc8017.pdf (Thanks @andre-stefanov :) )

The idea is to create a ramp lib that can be integrated in any driver, the step counting for the driver itself stay unaffected by integration a ramp lib

I have been using Shell to see how the ramping looks like.

Starting This PR to get some early feedback.

Known open points:

Integrate ramp control for stepper_run as well
use of sqrt in calculate_start_velocity, this function gets called once when the ramping starts from zero-velocity
Implement unit tests
Introduce DT based selection of trapezoidal ramp, allowing inclusion of other ramps in future

drivers/stepper/ramp/ramp.h

include/zephyr/drivers/stepper.h

drivers/stepper/ramp/ramp_trapezoidal.c

andre-stefanov · 2025-04-13T21:40:49Z

include/zephyr/drivers/stepper.h

+	/** Ramp acceleration in micro-steps per second squared */
+	uint32_t acceleration;
+	/** Ramp maximum velocity in micro-steps per second */
+	uint32_t max_velocity;


is max_velocity really needed? next step interval depends only on current interval and acceleration/deceleration values.

the actual limit will be given by the requested stepper interval

Trying to depict a trapezoidal ramp. I am also using max_velocity to check for valid_timing in move_by and move_to. But i'll check this again for sure if it is actually needed :).

In my experience, the speed set via set_microstep_interval is sufficient.

Okay we can use that function, but we definitely need to have a better name for it though. set_microstep_interval atleast imo sounds like this interval will take place with immediate effect. Probably something like set_target_step_interval ?

jbehrensnx · 2025-04-14T06:32:30Z

include/zephyr/drivers/stepper.h

+	/** Ramp acceleration in micro-steps per second squared */
+	uint32_t acceleration;
+	/** Ramp maximum velocity in micro-steps per second */
+	uint32_t max_velocity;


In my experience, the speed set via set_microstep_interval is sufficient.

drivers/stepper/gpio_stepper_controller.c

jbehrensnx · 2025-04-14T07:07:13Z

drivers/stepper/gpio_stepper_controller.c

+
+	K_SPINLOCK(&data->lock) {
+		data->ramp_common.ramp_profile.acceleration = ramp_profile->acceleration;
+		data->ramp_common.ramp_profile.max_velocity = ramp_profile->max_velocity;


You don't need max_velocity, you already have set_microstep_interval.

We need to find a consensus on how to rename that function, set_microstep_interval imo signifies more like a tick time, could be compared with for instance , can_set_bitrate.

jbehrensnx · 2025-04-14T07:13:37Z

drivers/stepper/ramp/Kconfig

+
+if STEPPER_RAMP
+
+config STEPPER_RAMP_TRAPEZOIDAL


I would prefer a dt-binding instead to allow for a per stepper-controller decision on using ramps or not.

done. However, you would need one such variable for the source to be included, or is there a better way?

jbehrensnx · 2025-04-14T07:20:55Z

drivers/stepper/ramp/ramp_trapezoidal.c

+	switch (ramp_data->current_ramp_state) {
+	case STEPPER_RAMP_STATE_ACCELERATION:
+		ramp_data->ramp_actual_position++;
+		new_step_interval_in_ns = current_step_interval_in_ns -


You cant always use the approximation. You will need to use the accurate algorithm using the sqrt for a number of steps after starting accelerating and a couple of steps before stopping when decelerating. This is because of the approximation error.

jbehrensnx · 2025-04-14T07:24:48Z

My PR 88342 already uses the same algorithm (through I forgot to mention the algorithm admittedly) for a step-dir implementation. Several decisions made during development for that are relevant for this PR as well, so it should be included in the discussion.

dts/bindings/stepper/ramp-parameters.yaml

dipakgmx · 2025-04-14T21:20:39Z

This is not related to the changes made in this PR, but could the functions move_to & move_by call either of them, I mean, in move_by, call move_to(current_pos+move_by_target)? It seems to me that some bits of code are repeated in both the functions (or thats what I felt when reviewing)

jilaypandya · 2025-04-14T21:24:42Z

This is not related to the changes made in this PR, but could the functions move_to & move_by call either of them, I mean, in move_by, call move_to(current_pos+move_by_target)? It seems to me that some bits of code are repeated in both the functions (or thats what I felt when reviewing)

you are right, move_to should call move_by. When can i expect a patch from you :-)

Copilot

Pull Request Overview

This PR introduces rudimentary ramp control for stepper drivers by implementing a trapezoidal ramp algorithm and integrating ramp profile support into both generic and GPIO stepper drivers. Key changes include:

Integrating a ramp profile in the main application code for the generic stepper driver.
Adding device tree bindings and header definitions for ramp parameters.
Implementing a trapezoidal ramp algorithm and integrating its API into the GPIO driver.

Reviewed Changes

Copilot reviewed 11 out of 18 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
samples/drivers/stepper/generic/src/main.c	Initializes and applies ramp profile in main for driver testing.
include/zephyr/dt-bindings/stepper/ramp.h	Defines ramp type constants for DT binding.
include/zephyr/drivers/stepper/stepper_ramp.h	Declares the ramp profile structure and APIs.
include/zephyr/drivers/stepper.h	Integrates ramp profile API into the stepper driver interface.
dts/bindings/stepper/zephyr,gpio-stepper.yaml	Adds ramp parameters inclusion for DT configuration.
dts/bindings/stepper/ramp-parameters.yaml	Provides DT properties for ramp configuration.
drivers/stepper/stepper_common.h	Introduces common stepper run modes.
drivers/stepper/step_dir/step_dir_stepper_common.h	Uses common stepper definitions.
drivers/stepper/ramp/ramp_trapezoidal.c	Implements the trapezoidal ramp algorithm logic.
drivers/stepper/ramp/ramp.h	Declares ramp API and supporting structures.
drivers/stepper/gpio_stepper_controller.c	Integrates ramp control logic within the GPIO stepper driver.

Files not reviewed (7)

drivers/stepper/CMakeLists.txt: Language not supported
drivers/stepper/Kconfig: Language not supported
drivers/stepper/ramp/CMakeLists.txt: Language not supported
drivers/stepper/ramp/Kconfig: Language not supported
samples/drivers/stepper/generic/Kconfig: Language not supported
samples/drivers/stepper/generic/boards/nucleo_g071rb.overlay: Language not supported
samples/drivers/stepper/generic/prj.conf: Language not supported

Comments suppressed due to low confidence (1)

drivers/stepper/gpio_stepper_controller.c:388

Using a magic number (10000) for steps in the ramp reset call reduces code clarity and flexibility. Consider defining a named constant or using a DT property for improved maintainability.

config->ramp_api->reset_ramp_data(&config->ramp_config, &data->ramp_common, &data->delay_in_ns, is_dir_changed, is_stepper_moving, 10000);

drivers/stepper/ramp/ramp_trapezoidal.c

Introduce rudimentary control using following paper: https://www.boost.org/doc/libs/1_81_0/libs/safe_numerics/example/stepper-motor.pdf Signed-off-by: Jilay Pandya <[email protected]>

github-actions bot added area: Stepper area: Samples area: Devicetree labels Apr 13, 2025

github-actions bot requested review from bjarki-andreasen, decsny, dipakgmx, fabiobaltieri, faxe1008, galak, jbehrensnx, kartben, nashif and rruuaanng April 13, 2025 19:26

github-actions bot assigned kartben Apr 13, 2025

jilaypandya force-pushed the feature/introduce-rudimentary-ramp branch from 3eb28c1 to d4a1f59 Compare April 13, 2025 19:31

jilaypandya mentioned this pull request Apr 13, 2025

Stepper API: Set Ramp Profile #88563

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drivers: stepper: introduce rudimentary ramp control

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Introduce rudimentary control using following paper: https://www.boost.org/doc/libs/1_81_0/libs/safe_numerics/example/stepper-motor.pdf Signed-off-by: Jilay Pandya <[email protected]>

jilaypandya force-pushed the feature/introduce-rudimentary-ramp branch from dd51fb8 to 67e6a1e Compare April 17, 2025 21:33

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drivers: stepper: introduce rudimentary ramp control #88564

drivers: stepper: introduce rudimentary ramp control #88564

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