C路: VL53L0X 用户态I2C直驱 + 高速模式 29.6fps

- 搬运 ST API C 源码到 lib/vl53l0x/, 替换 I2C 层为用户态 i2c-dev
- 新增 vl53l0x_platform_user.cpp: WriteMulti/ReadMulti 等全平台接口
- 重写 vl53l0x.cpp: start时unbind内核驱动, 单次测距, 无后台轮询
- 高速模式 20000μs timing budget, 模型缓存零污染(41-43ms)
- LiDAR 每5帧一读(~20ms), 隔帧模型推理, fps 25.1→29.6 (+18%)
- 同事的LiDAR避障集成: 12个配置参数, 中线变形绕行, 刹车注释
- nice -10 + sched_yield 优先级优化

AGENTS.md

@@ -38,6 +38,8 @@ These source files exist but are **excluded from build**:
 
 - `vl53l0x.cpp` — laser ranging module, hardware not connected
 - `zebra_detect.cpp` — classic zebra-crossing detection (replaced by Mild model)
+- `PIDController.cpp` — unused (motor is open-loop direct drive)
+- `serial.cpp` — Vofa/serial image streaming, unused
 
 ## Device-side operation
 
@@ -52,7 +54,7 @@ sh ctl.sh stop          # stop and zero PWM
 
 `ctl.sh` sets default config values by writing to files like `./speed`, `./kp`, `./steer_gain`, etc. The running binary reads these files at startup and optionally re-reads them every 7 frames (when `./debug` = 1).
 
-`start.sh` is an alternative launcher using `LD_PRELOAD=./gpio_fix_final.so` for the GPIO 74 workaround.
+`start.sh` is an alternative launcher using `LD_PRELOAD=./gpio_fix_final.so` for the GPIO 74 workaround. **Note**: `start.sh` references the binary as `smartcar_demo` but the actual executable is `smartcar_demo1` — this is a known bug, use `ctl.sh` instead.
 
 ## Configuration system
 
@@ -94,7 +96,7 @@ All config is via single-value text files in the working directory:
 
 ## Architecture
 
-### Per-frame pipeline in `CameraHandler()` ([`src/camera.cpp`](file:///D:\PPPProgram\smartcar\smartcar2\src\camera.cpp))
+### Per-frame pipeline in `CameraHandler()` (`src/camera.cpp:578`)
 
 CameraHandler 现已拆分为多个函数，主函数 ~40 行仅做编排：
 
@@ -117,7 +119,7 @@ CameraHandler()
 
 - **Open-loop**: `MotorController::updateduty(spd)` — direct PWM duty cycle, no encoder feedback in normal driving.
 - **Encoder brake**: When `zebra_block=true` (red light or zebra stop), reads `g_enc_speed` from the encoder thread and applies reverse braking proportional to current speed.
-- **Encoder thread** ([`control.cpp:32`](file:///D:\PPPProgram\smartcar\smartcar2\src\control.cpp#L32)): polls GPIO67 (LSB pulse) + GPIO72 (direction) at ~2kHz, 100ms window speed calculation → `g_enc_speed` (pulses/sec). Now includes 500µs sleep to prevent CPU starvation.
+- **Encoder thread** (`control.cpp:32`): polls GPIO67 (LSB pulse) + GPIO72 (direction) at ~2kHz, 100ms window speed calculation → `g_enc_speed` (pulses/sec). Now includes 500µs sleep to prevent CPU starvation.
 - **Curve slowdown**: `speed *= (1.0 - |deviation| × 0.4)`, clamped to ≥ 60%.
 
 ### Model: Mild v12