feat: camera module — OV3660 init and 96x96 grayscale capture

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

firmware/src/camera.cpp

@@ -0,0 +1,88 @@
+// firmware/src/camera.cpp
+// OV3660 pin assignments for M5Stack TimerCamera-F
+// Ref: https://docs.m5stack.com/en/unit/timercam_f
+#include "camera.h"
+#include "cv.h"
+#include "esp_camera.h"
+#include <string.h>
+
+#define CAM_PIN_PWDN  -1
+#define CAM_PIN_RESET 15
+#define CAM_PIN_XCLK  27
+#define CAM_PIN_SIOD  25
+#define CAM_PIN_SIOC  23
+#define CAM_PIN_D7    19
+#define CAM_PIN_D6    36
+#define CAM_PIN_D5    18
+#define CAM_PIN_D4    39
+#define CAM_PIN_D3     5
+#define CAM_PIN_D2    34
+#define CAM_PIN_D1    35
+#define CAM_PIN_D0    32
+#define CAM_PIN_VSYNC 22
+#define CAM_PIN_HREF  26
+#define CAM_PIN_PCLK  21
+
+bool camera_init() {
+    camera_config_t cfg = {};
+    cfg.ledc_channel = LEDC_CHANNEL_0;
+    cfg.ledc_timer   = LEDC_TIMER_0;
+    cfg.pin_d0       = CAM_PIN_D0;
+    cfg.pin_d1       = CAM_PIN_D1;
+    cfg.pin_d2       = CAM_PIN_D2;
+    cfg.pin_d3       = CAM_PIN_D3;
+    cfg.pin_d4       = CAM_PIN_D4;
+    cfg.pin_d5       = CAM_PIN_D5;
+    cfg.pin_d6       = CAM_PIN_D6;
+    cfg.pin_d7       = CAM_PIN_D7;
+    cfg.pin_xclk     = CAM_PIN_XCLK;
+    cfg.pin_pclk     = CAM_PIN_PCLK;
+    cfg.pin_vsync    = CAM_PIN_VSYNC;
+    cfg.pin_href     = CAM_PIN_HREF;
+    cfg.pin_sscb_sda = CAM_PIN_SIOD;
+    cfg.pin_sscb_scl = CAM_PIN_SIOC;
+    cfg.pin_pwdn     = CAM_PIN_PWDN;
+    cfg.pin_reset    = CAM_PIN_RESET;
+    cfg.xclk_freq_hz = 20000000;
+    cfg.pixel_format = PIXFORMAT_GRAYSCALE;
+    cfg.frame_size   = FRAMESIZE_QVGA;  // 320x240
+    cfg.fb_count     = 1;
+    cfg.grab_mode    = CAMERA_GRAB_WHEN_EMPTY;
+
+    esp_err_t err = esp_camera_init(&cfg);
+    if (err != ESP_OK) return false;
+
+    // Flip vertically — adjust if mounting orientation differs
+    sensor_t* s = esp_camera_sensor_get();
+    s->set_vflip(s, 1);
+    s->set_hmirror(s, 0);
+
+    return true;
+}
+
+// Box-filter downscale from QVGA (320x240) to 96x96 grayscale
+static void downscale(const uint8_t* src, int src_w, int src_h, uint8_t* dst) {
+    int bx = src_w / CV_W;
+    int by = src_h / CV_H;
+    for (int dy = 0; dy < CV_H; dy++) {
+        for (int dx = 0; dx < CV_W; dx++) {
+            int sum = 0, cnt = 0;
+            for (int ky = 0; ky < by; ky++)
+                for (int kx = 0; kx < bx; kx++) {
+                    int sx = dx * bx + kx;
+                    int sy = dy * by + ky;
+                    sum += src[sy * src_w + sx];
+                    cnt++;
+                }
+            dst[dy * CV_W + dx] = (uint8_t)(sum / cnt);
+        }
+    }
+}
+
+bool camera_capture_96(uint8_t* buf) {
+    camera_fb_t* fb = esp_camera_fb_get();
+    if (!fb) return false;
+    downscale(fb->buf, fb->width, fb->height, buf);
+    esp_camera_fb_return(fb);
+    return true;
+}

firmware/src/camera.h

@@ -0,0 +1,11 @@
+// firmware/src/camera.h
+#pragma once
+#include <stdint.h>
+#include <stddef.h>
+
+// Initialise OV3660 camera for TimerCamera-F. Returns false on failure.
+bool camera_init();
+
+// Capture one frame, downscale to 96x96 grayscale, write into buf.
+// buf must be CV_PIXELS (9216) bytes. Returns false on capture failure.
+bool camera_capture_96(uint8_t* buf);