fix(polarizer-wheel): cleaner ramp, starts at 2s/turn speed

[fouge]

exact symetry of the pulses between the 2 positions cleaned code a bit

[Copilot]

Pull request overview

This PR refines the polarizer wheel motion profile by making the triangular ramp more symmetric and changing the ramp’s initial speed to start at 2s/turn, while also removing now-unused frequency bookkeeping fields.

Changes:

• Add a 2s/turn PWM frequency constant and use it as the ramp start/end frequency.
• Adjust ramp step computation to improve symmetry across the travel.
• Remove unused frequency/current_frequency fields and related updates.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 3 comments.

File	Description
main_board/src/optics/polarizer_wheel/polarizer_wheel.h	Adds a 2s/turn PWM frequency macro used by the updated ramp behavior.
main_board/src/optics/polarizer_wheel/polarizer_wheel.c	Updates ramp symmetry math, changes ramp start frequency, and removes unused state fields.

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[Copilot]

ramp_step can underflow when total_dist is 0 (e.g., if execute_set_angle() is called with target_step == current_step but target_position is UNKNOWN, so the early-return doesn’t trigger). With total_dist == 0, the expression (total_dist - distance_traveled - 1) wraps to a huge uint32_t, which then feeds calculate_linear_ramp_frequency() and may produce an invalid/erratic frequency. Consider guarding against zero-distance moves (preferably in execute_set_angle() before starting the motor), or at least handling total_dist == 0 in this ramp calculation to avoid unsigned wraparound. Adding a regression test for the zero-distance ramp move would help prevent this from reoccurring.

[Copilot]

In ramp mode, min_frequency is hard-coded to POLARIZER_WHEEL_SPIN_PWM_FREQUENCY_2SEC_PER_TURN, but polarizer_set_frequency() will reject any frequency above the runtime get_max_frequency() (derived from g_max_speed_ms_per_turn). If max speed is configured slower than 2s/turn (e.g., via polarizer_wheel_set_max_speed()), the initial polarizer_rotate(frequency) will fail immediately. Consider clamping the chosen ramp start frequency to get_max_frequency() (and/or validating set_max_speed inputs) so ramp mode remains usable across supported max-speed configurations.

[Copilot]

execute_set_angle() repurposes and mutates the frequency parameter (switching it from the caller-provided value to the internally chosen ramp start frequency). This makes the control flow harder to follow when debugging (especially since use_encoder/use_ramp are derived from the original value). Consider introducing a separate local like start_frequency (or similar) and keeping the input parameter unchanged, then pass the chosen start frequency to polarizer_rotate().