jiahong
330 lines
10 KiB
C
330 lines
10 KiB
C
/*
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* 自然写智能点阵笔嵌入式固件软件 V1.0
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* image_capture_task.c - 图像采集任务
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*
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* 功能说明：
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* 1. 以100Hz频率驱动CMOS图像传感器采集点阵图案
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* 2. DMA方式高速传输图像数据
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* 3. 笔尖接触检测（上升沿/下降沿中断）
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* 4. 图像帧质量快速评估（丢弃模糊帧）
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* 5. 采集参数自适应调节（曝光、增益）
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*/
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#include <stdint.h>
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#include <stdbool.h>
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#include <string.h>
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#include "FreeRTOS.h"
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#include "task.h"
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#include "queue.h"
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#include "event_groups.h"
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#include "camera_driver.h"
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#include "hal_spi.h"
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#include "hal_dma.h"
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#include "hal_gpio.h"
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/* ========== 常量定义 ========== */
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/* 采集频率（Hz） */
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#define CAPTURE_FREQUENCY_HZ 100
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/* 采集周期（毫秒） */
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#define CAPTURE_PERIOD_MS (1000 / CAPTURE_FREQUENCY_HZ)
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/* 图像传感器分辨率 */
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#define SENSOR_WIDTH 32
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#define SENSOR_HEIGHT 32
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#define SENSOR_PIXELS (SENSOR_WIDTH * SENSOR_HEIGHT)
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/* 单帧图像字节数（8位灰度） */
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#define FRAME_SIZE_BYTES SENSOR_PIXELS
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/* DMA传输缓冲区（双缓冲） */
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#define DMA_BUFFER_COUNT 2
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/* 图像质量阈值（低于此值判定为模糊/无效帧） */
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#define QUALITY_THRESHOLD 30
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/* 最大连续无效帧数（超过则认为笔离开纸面） */
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#define MAX_INVALID_FRAMES 5
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/* 自动曝光调节步长 */
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#define AUTO_EXPOSURE_STEP 4
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/* ========== 数据结构 ========== */
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/* 图像帧元数据（放入队列传递给坐标计算任务） */
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typedef struct {
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uint8_t *pixel_buffer; /* 指向DMA缓冲区的像素数据 */
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uint32_t frame_id; /* 帧序号 */
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uint32_t timestamp_ms; /* 采集时间戳 */
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uint8_t quality_score; /* 图像质量评分（0-255） */
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uint8_t exposure_value; /* 当前曝光值 */
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uint16_t pressure_raw; /* 同步采集的压力原始ADC值 */
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} ImageFrameMetadata;
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/* 传感器配置参数 */
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typedef struct {
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uint8_t exposure; /* 曝光时间（寄存器值） */
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uint8_t gain; /* 模拟增益 */
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uint8_t threshold; /* 二值化阈值 */
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bool auto_exposure_enabled; /* 是否启用自动曝光 */
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} SensorConfig;
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/* ========== 外部引用 ========== */
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extern QueueHandle_t g_image_data_queue;
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extern EventGroupHandle_t g_ble_event_group;
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/* ========== 静态变量 ========== */
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/* DMA双缓冲区 */
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static uint8_t s_dma_buffer[DMA_BUFFER_COUNT][FRAME_SIZE_BYTES]
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__attribute__((aligned(4)));
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/* 当前活跃的DMA缓冲区索引 */
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static volatile uint8_t s_active_buffer = 0;
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/* 帧计数器 */
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static uint32_t s_frame_counter = 0;
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/* 连续无效帧计数 */
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static uint8_t s_invalid_frame_count = 0;
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/* 传感器配置 */
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static SensorConfig s_sensor_config;
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/* 笔尖状态 */
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static volatile bool s_pen_touching = false;
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/* ========== 笔尖接触检测 ========== */
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/**
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* 笔尖接触检测GPIO中断回调
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* 通过检测微动开关或红外反射判断笔尖是否接触纸面
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*/
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void pen_tip_irq_handler(void) {
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bool state = hal_gpio_read(GPIO_PEN_TIP_PIN);
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BaseType_t higher_priority_woken = pdFALSE;
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if (state && !s_pen_touching) {
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/* 笔落下（接触纸面） */
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s_pen_touching = true;
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xEventGroupSetBitsFromISR(g_ble_event_group, EVT_PEN_DOWN,
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&higher_priority_woken);
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} else if (!state && s_pen_touching) {
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/* 笔抬起（离开纸面） */
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s_pen_touching = false;
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xEventGroupSetBitsFromISR(g_ble_event_group, EVT_PEN_UP,
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&higher_priority_woken);
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}
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portYIELD_FROM_ISR(higher_priority_woken);
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}
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/* ========== DMA传输完成回调 ========== */
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/**
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* SPI DMA传输完成中断回调
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* 图像数据已从传感器通过DMA传输到内存缓冲区
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*/
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void spi_dma_complete_handler(void) {
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/* 切换到另一个DMA缓冲区（乒乓缓冲） */
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s_active_buffer = (s_active_buffer + 1) % DMA_BUFFER_COUNT;
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}
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/* ========== 图像质量评估 ========== */
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/**
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* 快速评估图像帧质量
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* 通过计算图像的对比度（标准差近似）来判断是否有效
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* 有效的点阵图案应该有清晰的明暗对比
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*
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* @param pixels 像素数据
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* @param length 数据长度
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* @return 质量评分（0-255，越高越好）
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*/
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static uint8_t evaluate_frame_quality(const uint8_t *pixels, uint16_t length) {
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uint32_t sum = 0;
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uint32_t sum_sq = 0;
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uint16_t i;
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/* 采样统计（每4个像素取1个，减少计算量） */
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uint16_t sample_count = 0;
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for (i = 0; i < length; i += 4) {
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uint32_t val = pixels[i];
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sum += val;
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sum_sq += val * val;
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sample_count++;
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}
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if (sample_count == 0) return 0;
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/* 计算方差的近似值（反映对比度） */
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uint32_t mean = sum / sample_count;
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uint32_t variance = (sum_sq / sample_count) - (mean * mean);
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/* 方差映射到0-255评分 */
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if (variance > 2000) return 255;
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return (uint8_t)(variance * 255 / 2000);
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}
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/* ========== 自动曝光调节 ========== */
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/**
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* 根据图像亮度自动调节传感器曝光参数
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* 目标：使图像平均亮度保持在中间范围（100-150）
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*/
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static void auto_exposure_adjust(const uint8_t *pixels, uint16_t length) {
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if (!s_sensor_config.auto_exposure_enabled) {
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return;
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}
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/* 计算平均亮度 */
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uint32_t sum = 0;
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uint16_t i;
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for (i = 0; i < length; i += 8) {
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sum += pixels[i];
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}
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uint8_t avg_brightness = (uint8_t)(sum / (length / 8));
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/* 根据亮度偏差调节曝光值 */
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if (avg_brightness < 80 && s_sensor_config.exposure < 250) {
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/* 过暗，增加曝光 */
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s_sensor_config.exposure += AUTO_EXPOSURE_STEP;
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camera_set_exposure(s_sensor_config.exposure);
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} else if (avg_brightness > 170 && s_sensor_config.exposure > AUTO_EXPOSURE_STEP) {
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/* 过亮，减少曝光 */
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s_sensor_config.exposure -= AUTO_EXPOSURE_STEP;
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camera_set_exposure(s_sensor_config.exposure);
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}
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}
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/* ========== 传感器初始化 ========== */
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/**
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* 配置CMOS图像传感器初始参数
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*/
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static void sensor_setup(void) {
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/* 设置默认曝光和增益 */
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s_sensor_config.exposure = 128;
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s_sensor_config.gain = 64;
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s_sensor_config.threshold = 128;
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s_sensor_config.auto_exposure_enabled = true;
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/* 写入传感器寄存器 */
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camera_set_exposure(s_sensor_config.exposure);
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camera_set_gain(s_sensor_config.gain);
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/* 配置为连续帧模式 */
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camera_set_mode(CAMERA_MODE_CONTINUOUS);
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/* 配置SPI DMA接收 */
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hal_dma_config(DMA_CHANNEL_SPI_RX,
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(uint32_t)camera_get_data_register(),
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(uint32_t)s_dma_buffer[0],
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FRAME_SIZE_BYTES);
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}
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/* ========== 图像采集主任务 ========== */
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/**
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* 图像采集任务（FreeRTOS任务函数）
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*
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* 运行流程：
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* 1. 等待笔尖接触纸面
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* 2. 以100Hz频率触发CMOS传感器拍摄
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* 3. DMA传输图像数据到双缓冲区
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* 4. 评估图像质量，丢弃无效帧
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* 5. 将有效帧元数据放入队列供坐标计算任务处理
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* 6. 笔抬起后暂停采集，进入低功耗等待
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*/
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void image_capture_task(void *pvParameters) {
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(void)pvParameters;
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TickType_t last_wake_time;
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/* 初始化传感器参数 */
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sensor_setup();
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/* 注册笔尖GPIO中断 */
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hal_gpio_set_irq(GPIO_PEN_TIP_PIN, GPIO_IRQ_BOTH_EDGE, pen_tip_irq_handler);
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while (1) {
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/* 等待笔落下事件（低功耗阻塞） */
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xEventGroupWaitBits(g_ble_event_group, EVT_PEN_DOWN,
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pdTRUE, pdFALSE, portMAX_DELAY);
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/* 笔已接触纸面，启动高速采集 */
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camera_power_on();
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/* 重置帧计数和无效帧计数 */
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s_frame_counter = 0;
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s_invalid_frame_count = 0;
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/* 记录采集起始时间 */
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last_wake_time = xTaskGetTickCount();
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/* 采集循环：持续采集直到笔抬起 */
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while (s_pen_touching) {
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/* 触发传感器拍摄 */
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camera_trigger_capture();
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/* 启动DMA传输（异步，CPU可做其他事） */
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uint8_t current_buffer = s_active_buffer;
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hal_dma_start(DMA_CHANNEL_SPI_RX,
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(uint32_t)s_dma_buffer[current_buffer],
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FRAME_SIZE_BYTES);
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/* 等待DMA完成（通常< 1ms） */
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hal_dma_wait_complete(DMA_CHANNEL_SPI_RX, 5);
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/* 同步读取压力传感器ADC值 */
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uint16_t pressure_raw = pressure_sensor_read_raw();
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/* 评估图像质量 */
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uint8_t quality = evaluate_frame_quality(
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s_dma_buffer[current_buffer], FRAME_SIZE_BYTES);
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if (quality >= QUALITY_THRESHOLD) {
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/* 有效帧，放入队列 */
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ImageFrameMetadata metadata;
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metadata.pixel_buffer = s_dma_buffer[current_buffer];
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metadata.frame_id = s_frame_counter;
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metadata.timestamp_ms = xTaskGetTickCount() * portTICK_PERIOD_MS;
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metadata.quality_score = quality;
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metadata.exposure_value = s_sensor_config.exposure;
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metadata.pressure_raw = pressure_raw;
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/* 非阻塞方式入队（如果队列满则丢弃） */
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xQueueSend(g_image_data_queue, &metadata, 0);
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s_invalid_frame_count = 0;
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} else {
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s_invalid_frame_count++;
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/* 连续多个无效帧，可能笔已离开但中断未触发 */
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if (s_invalid_frame_count >= MAX_INVALID_FRAMES) {
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s_pen_touching = false;
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break;
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}
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}
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/* 每16帧调整一次曝光（避免频繁调节） */
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if ((s_frame_counter & 0x0F) == 0) {
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auto_exposure_adjust(s_dma_buffer[current_buffer], FRAME_SIZE_BYTES);
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}
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s_frame_counter++;
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/* 精确定时：等待到下一个采集时间点 */
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vTaskDelayUntil(&last_wake_time, pdMS_TO_TICKS(CAPTURE_PERIOD_MS));
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}
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/* 笔抬起，关闭传感器降低功耗 */
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camera_power_off();
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}
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}
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