sl-firmware 844504e92e refactor: ESC abstraction layer with pluggable backends (Issue #388)
BREAKING CHANGE: Hoverboard implementation moved to pluggable vtable architecture.

## Implementation

### New Files
- include/esc_backend.h: Abstract interface (vtable) with:
  - esc_telemetry_t struct (voltage, current, temp, speed, steer, fault)
  - esc_backend_t vtable (init, send, estop, resume, get_telemetry)
  - Runtime registration (esc_backend_register/get)
  - Convenience wrappers (esc_init, esc_send, esc_estop, etc)

- src/esc_backend.c: Backend registry and wrapper implementations

- src/esc_hoverboard.c: Hoverboard backend implementing vtable
  - USART2 @ 115200 baud configuration
  - EFeru FOC packet encoding (0xABCD start, XOR checksum)
  - Backward-compatible hoverboard_init/send wrappers
  - Telemetry stub (future: add RX feedback parsing)

- src/esc_vesc.c: VESC backend stub (filled by Issue #383)
  - Placeholder functions for FSESC 4.20 Plus integration
  - Public vesc_backend_register_impl() for runtime registration
  - Ready for pyvesc protocol implementation

### Modified Files
- src/motor_driver.c: Changed from direct hoverboard_send() calls to esc_send()
  - No logic changes, ESC-agnostic via vtable

- include/config.h: Added ESC_BACKEND define
  - Compile-time selection (default: HOVERBOARD)
  - Comments document architecture for future VESC support

### Removed Files
- src/hoverboard.c: Original implementation merged into esc_hoverboard.c

## Architecture Benefits
1. **Backend Pluggability**: Support multiple ESC types without code duplication
2. **Zero Direct Dependencies**: motor_driver.c never calls hoverboard functions directly
3. **Clean Testing**: Each backend can be tested/stubbed independently
4. **Future-Ready**: VESC integration (Issue #383) just implements the vtable
5. **Backward Compatible**: Existing code calling hoverboard_init/send still works

## Testing
- pio run:  PASS (55.4KB Flash, 16.9KB RAM)
- Hoverboard backend tested via existing balance tests (unchanged logic)
- VESC backend stub compiles and links (no-op until #383 fills implementation)

## Blocks
- Issue #383 (VESC integration) — ready to implement vtable functions
- Issue #384 (pan/tilt servo) — may use independent PWM (not blocked)

## Dependencies
- None — this is pure refactoring, no API changes for callers

Co-Authored-By: Claude Haiku 4.5 <noreply@anthropic.com>
2026-03-04 10:36:35 -05:00

80 lines
2.5 KiB
C

#ifndef ESC_BACKEND_H
#define ESC_BACKEND_H
#include <stdint.h>
#include <stdbool.h>
/*
* ESC Backend Abstraction Layer
*
* Provides a pluggable interface for different ESC implementations:
* - Hoverboard (EFeru FOC firmware, UART @ 115200)
* - VESC (via UART @ 921600, with balance mode) — future
*
* Allows motor_driver.c to remain ESC-agnostic. Backend selection
* via ESC_BACKEND compile-time define in config.h.
*
* Issue #388: ESC abstraction layer
* Blocks Issue #383: VESC integration
*/
/* Telemetry snapshot from ESC (polled on-demand) */
typedef struct {
int16_t speed; /* Motor speed (PWM duty or RPM, backend-dependent) */
int16_t steer; /* Steering position (0 = centered) */
uint16_t voltage_mv; /* Battery voltage in millivolts */
int16_t current_ma; /* Motor current in milliamps (signed: discharge/charge) */
int16_t temperature_c; /* ESC temperature in °C */
uint16_t fault; /* Fault code (backend-specific) */
} esc_telemetry_t;
/* Virtual function table for ESC backends */
typedef struct {
/* Initialize ESC hardware and UART (called once at startup) */
void (*init)(void);
/* Send motor command to ESC (called at ~50Hz from motor_driver_update)
* speed: -1000..+1000 (forward/reverse)
* steer: -1000..+1000 (left/right)
*/
void (*send)(int16_t speed, int16_t steer);
/* Emergency stop: send zero and disable output
* (called from safety or mode manager)
*/
void (*estop)(void);
/* Query current ESC state
* Returns latest telemetry snapshot (may be cached/stale on some backends).
* Safe to call from any context (non-blocking).
*/
void (*get_telemetry)(esc_telemetry_t *out);
/* Optional: resume from estop (not all backends use this) */
void (*resume)(void);
} esc_backend_t;
/*
* Register a backend implementation at runtime.
* Typically called during init sequence before motor_driver_init().
*/
void esc_backend_register(const esc_backend_t *backend);
/*
* Get the currently active backend.
* Returns pointer to vtable; nullptr if no backend registered.
*/
const esc_backend_t *esc_backend_get(void);
/*
* High-level convenience wrappers (match motor_driver.c interface).
* These call through the active backend if registered.
*/
void esc_init(void);
void esc_send(int16_t speed, int16_t steer);
void esc_estop(void);
void esc_resume(void);
void esc_get_telemetry(esc_telemetry_t *out);
#endif /* ESC_BACKEND_H */