saltylab-firmware/src/motor_driver.c
sl-controls 80a41e5008 feat: motor driver layer — differential drive, steer ramp, estop
Adds motor_driver.c/h between the balance PID and the raw
hoverboard UART driver:

- Differential drive: balance_cmd → speed, steer_cmd → steer
- Steer-only ramping at MOTOR_STEER_RAMP_RATE (balance PID keeps
  full immediate authority — no ramp on speed channel)
- Headroom clamp: reduces steer so |speed|+|steer|<=MOTOR_CMD_MAX
  ensuring ESC never clips the balance command
- Emergency stop: latches on TILT_FAULT, clears on BALANCE_DISARMED;
  send path stays in 50Hz ESC tick to avoid flooding UART

main.c: replace bare hoverboard_send() with motor_driver_update();
config.h: MOTOR_CMD_MAX=1000, MOTOR_STEER_RAMP_RATE=20 counts/ms

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
2026-02-28 17:15:40 -05:00

59 lines
2.0 KiB
C

#include "motor_driver.h"
#include "hoverboard.h"
#include "config.h"
#include <stdlib.h>
void motor_driver_init(motor_driver_t *m) {
m->steer_actual = 0;
m->estop = false;
}
void motor_driver_update(motor_driver_t *m,
int16_t balance_cmd,
int16_t steer_cmd,
uint32_t now) {
static uint32_t s_last_tick = 0;
/* Delta-time for ramp (cap at 100ms to handle first call / long gaps).
* Always update tick so ramp starts fresh when estop clears. */
int32_t dt_ms = (int32_t)(now - s_last_tick);
if (dt_ms > 100) dt_ms = 100;
s_last_tick = now;
/* Emergency stop: send zero, hold latch */
if (m->estop) {
hoverboard_send(0, 0);
return;
}
/* Ramp steer toward target at MOTOR_STEER_RAMP_RATE counts/ms */
int32_t max_step = (int32_t)MOTOR_STEER_RAMP_RATE * dt_ms;
int32_t steer_error = (int32_t)steer_cmd - (int32_t)m->steer_actual;
if (steer_error > max_step) steer_error = max_step;
else if (steer_error < -max_step) steer_error = -max_step;
m->steer_actual = (int16_t)((int32_t)m->steer_actual + steer_error);
/* Headroom clamp: ensure |speed| + |steer| <= MOTOR_CMD_MAX
* Reduce steer (not balance) to preserve PID authority. */
int32_t speed = (int32_t)balance_cmd;
int32_t steer = (int32_t)m->steer_actual;
int32_t headroom = MOTOR_CMD_MAX - abs((int)speed);
if (headroom < 0) headroom = 0;
if (steer > headroom) steer = headroom;
if (steer < -headroom) steer = -headroom;
hoverboard_send((int16_t)speed, (int16_t)steer);
}
void motor_driver_estop(motor_driver_t *m) {
m->estop = true;
m->steer_actual = 0;
/* Don't call hoverboard_send here — caller must drive sends via
* motor_driver_update() at the normal 50Hz ESC rate to avoid
* flooding the UART with 1kHz zero packets. */
}
void motor_driver_estop_clear(motor_driver_t *m) {
m->estop = false;
}