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jiahong
2026-03-22 15:24:40 +08:00
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software-copyright/04-writech-gateway/protocol/protocol_converter.c
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/**
* 自然写教室智能网关管理软件 V1.0
*
* protocol_converter.c - BLE到MQTT协议转换模块
*
* 功能说明：
* - BLE原始帧解析为结构化笔迹数据
* - 笔迹数据编码为MQTT JSON/二进制负载
* - 多种消息类型转换（笔迹/状态/控制）
* - 数据压缩与批量打包
* - 消息序列号管理与去重
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdint.h>
#include <stdbool.h>
#include <time.h>
#include <math.h>
/* ======================== 常量与类型定义 ======================== */
/* BLE帧类型标识 */
#define BLE_FRAME_STROKE 0x01 /* 笔迹坐标帧 */
#define BLE_FRAME_PAGE_TURN 0x02 /* 翻页事件帧 */
#define BLE_FRAME_PEN_STATE 0x03 /* 笔状态帧（抬笔/落笔） */
#define BLE_FRAME_BATTERY 0x04 /* 电量上报帧 */
#define BLE_FRAME_HEARTBEAT 0x05 /* 心跳帧 */
#define BLE_FRAME_OTA_ACK 0x06 /* OTA响应帧 */
/* MQTT消息类型 */
#define MQTT_MSG_STROKE 0x10 /* 笔迹数据消息 */
#define MQTT_MSG_EVENT 0x20 /* 事件通知消息 */
#define MQTT_MSG_STATUS 0x30 /* 设备状态消息 */
#define MQTT_MSG_COMMAND_ACK 0x40 /* 命令应答消息 */
/* 协议参数 */
#define MAX_BATCH_POINTS 64 /* 单批次最大坐标点数 */
#define MAX_JSON_BUFFER 4096 /* JSON缓冲区大小 */
#define MAX_BINARY_PAYLOAD 2048 /* 二进制负载最大长度 */
#define COMPRESS_THRESHOLD 128 /* 触发压缩的数据量阈值(字节) */
#define SEQUENCE_NUM_MAX 65535 /* 序列号最大值 */
/* CRC-16 CCITT多项式 */
#define CRC16_CCITT_POLY 0x1021
/* BLE原始帧头结构 (与笔固件协议一致) */
typedef struct {
uint8_t sync_byte; /* 同步字节 0xAA */
uint8_t frame_type; /* 帧类型 */
uint8_t pen_id[6]; /* 笔MAC地址 */
uint16_t payload_len; /* 负载长度 */
uint16_t sequence; /* 帧序列号 */
} __attribute__((packed)) ble_frame_header_t;
/* 7字节紧凑坐标编码结构 (与笔端一致) */
typedef struct {
uint32_t x_coord : 20; /* X坐标 0-1048575 */
uint32_t y_coord : 20; /* Y坐标 0-1048575 */
uint16_t pressure : 12; /* 压力值 0-4095 */
uint8_t flags : 4; /* 标志位 */
} stroke_point_compact_t;
/* 解码后的笔迹坐标点 */
typedef struct {
float x; /* X坐标（毫米） */
float y; /* Y坐标（毫米） */
float pressure; /* 压力值（归一化 0.0-1.0） */
uint32_t timestamp_ms; /* 时间戳（毫秒） */
uint8_t pen_down; /* 落笔标志 */
} decoded_point_t;
/* MQTT负载结构 */
typedef struct {
char topic[128]; /* MQTT主题 */
uint8_t payload[MAX_BINARY_PAYLOAD]; /* 负载数据 */
uint32_t payload_len; /* 负载长度 */
uint8_t qos; /* QoS等级 */
bool retain; /* 保留标志 */
uint16_t msg_seq; /* 消息序列号 */
} mqtt_message_t;
/* 协议转换器上下文 */
typedef struct {
char gateway_id[32]; /* 网关标识 */
uint16_t next_sequence; /* 下一个消息序列号 */
uint16_t last_ble_seq[64]; /* 各笔最后BLE序列号(去重) */
uint32_t total_converted; /* 总转换消息数 */
uint32_t total_dropped; /* 丢弃的重复消息数 */
uint32_t error_count; /* 错误计数 */
bool use_binary_format; /* 是否使用二进制格式 */
bool compression_enabled; /* 是否启用压缩 */
} protocol_converter_ctx_t;
/* 全局协议转换器实例 */
static protocol_converter_ctx_t g_converter;
/* ======================== CRC校验 ======================== */
/**
* 计算CRC-16 CCITT校验值
* 用于验证BLE帧数据完整性
*/
static uint16_t crc16_ccitt(const uint8_t *data, uint32_t length)
{
uint16_t crc = 0xFFFF;
for (uint32_t i = 0; i < length; i++) {
crc ^= (uint16_t)data[i] << 8;
for (int j = 0; j < 8; j++) {
if (crc & 0x8000) {
crc = (crc << 1) ^ CRC16_CCITT_POLY;
} else {
crc <<= 1;
}
}
}
return crc;
}
/* ======================== BLE帧解析 ======================== */
/**
* 验证BLE帧头有效性
* 检查同步字节、帧类型范围、负载长度合理性
*/
static bool validate_ble_frame(const uint8_t *raw_data, uint32_t raw_len)
{
if (raw_len < sizeof(ble_frame_header_t) + 2) {
/* 数据长度不足（帧头 + CRC-16） */
return false;
}
const ble_frame_header_t *header = (const ble_frame_header_t *)raw_data;
/* 检查同步字节 */
if (header->sync_byte != 0xAA) {
return false;
}
/* 检查帧类型范围 */
if (header->frame_type < BLE_FRAME_STROKE ||
header->frame_type > BLE_FRAME_OTA_ACK) {
return false;
}
/* 检查负载长度合理性 */
uint32_t expected_len = sizeof(ble_frame_header_t) + header->payload_len + 2;
if (expected_len > raw_len || header->payload_len > MAX_BINARY_PAYLOAD) {
return false;
}
/* CRC校验 - 计算帧头+负载的CRC并与尾部CRC比较 */
uint32_t data_len = sizeof(ble_frame_header_t) + header->payload_len;
uint16_t calc_crc = crc16_ccitt(raw_data, data_len);
uint16_t recv_crc = *(uint16_t *)(raw_data + data_len);
if (calc_crc != recv_crc) {
g_converter.error_count++;
return false;
}
return true;
}
/**
* 解码7字节紧凑坐标为浮点坐标
* 坐标单位从点阵码单位转换为毫米
* 压力值归一化到0.0-1.0范围
*/
static void decode_compact_point(const uint8_t *compact_data,
decoded_point_t *point)
{
/* 从7字节紧凑编码中提取各字段 */
uint32_t raw_x = ((uint32_t)compact_data[0] << 12) |
((uint32_t)compact_data[1] << 4) |
((compact_data[2] >> 4) & 0x0F);
uint32_t raw_y = ((uint32_t)(compact_data[2] & 0x0F) << 16) |
((uint32_t)compact_data[3] << 8) |
compact_data[4];
uint16_t raw_pressure = ((uint16_t)compact_data[5] << 4) |
((compact_data[6] >> 4) & 0x0F);
uint8_t flags = compact_data[6] & 0x0F;
/* 坐标转换：点阵码坐标 → 毫米（分辨率约0.3mm/单位） */
point->x = (float)raw_x * 0.3f;
point->y = (float)raw_y * 0.3f;
/* 压力值归一化到 0.0-1.0 */
point->pressure = (float)raw_pressure / 4095.0f;
/* 落笔标志在flags低位 */
point->pen_down = (flags & 0x01) ? 1 : 0;
}
/**
* 解析BLE笔迹帧为坐标点数组
* 返回实际解码的坐标点数量
*/
static int parse_stroke_frame(const uint8_t *payload, uint16_t payload_len,
decoded_point_t *points, int max_points)
{
/* 每个坐标点占7字节紧凑编码 + 4字节时间戳 = 11字节 */
int point_size = 11;
int num_points = payload_len / point_size;
if (num_points > max_points) {
num_points = max_points;
}
for (int i = 0; i < num_points; i++) {
const uint8_t *point_data = payload + (i * point_size);
/* 解码紧凑坐标 */
decode_compact_point(point_data, &points[i]);
/* 提取时间戳 (小端序，4字节毫秒时间戳) */
points[i].timestamp_ms = (uint32_t)point_data[7] |
((uint32_t)point_data[8] << 8) |
((uint32_t)point_data[9] << 16) |
((uint32_t)point_data[10] << 24);
}
return num_points;
}
/* ======================== 序列号去重 ======================== */
/**
* 检查BLE帧序列号是否重复
* 使用滑动窗口检测重复帧，防止BLE重传导致数据重复
*/
static bool is_duplicate_frame(uint8_t pen_index, uint16_t ble_sequence)
{
if (pen_index >= 64) {
return false;
}
uint16_t last_seq = g_converter.last_ble_seq[pen_index];
/* 考虑序列号回绕：如果新序列号在旧序列号的合理范围内则认为重复 */
if (ble_sequence == last_seq) {
g_converter.total_dropped++;
return true;
}
/* 更新最后序列号 */
g_converter.last_ble_seq[pen_index] = ble_sequence;
return false;
}
/**
* 分配下一个MQTT消息序列号
* 单调递增，到达最大值后回绕
*/
static uint16_t allocate_msg_sequence(void)
{
uint16_t seq = g_converter.next_sequence;
g_converter.next_sequence = (seq + 1) % (SEQUENCE_NUM_MAX + 1);
return seq;
}
/* ======================== JSON编码 ======================== */
/**
* 将笔迹坐标数组编码为JSON格式
* 格式: {"pen_id":"xx:xx:xx","seq":N,"points":[{"x":1.2,"y":3.4,"p":0.5,"t":123},...]}
*/
static int encode_stroke_json(const char *pen_id_str,
const decoded_point_t *points, int num_points,
char *json_buf, int buf_size)
{
int offset = 0;
/* JSON头部 */
offset += snprintf(json_buf + offset, buf_size - offset,
"{\"gw\":\"%s\",\"pen\":\"%s\",\"seq\":%u,\"ts\":%lu,\"pts\":[",
g_converter.gateway_id, pen_id_str,
allocate_msg_sequence(), (unsigned long)time(NULL));
/* 编码每个坐标点 */
for (int i = 0; i < num_points && offset < buf_size - 64; i++) {
if (i > 0) {
json_buf[offset++] = ',';
}
offset += snprintf(json_buf + offset, buf_size - offset,
"{\"x\":%.2f,\"y\":%.2f,\"p\":%.3f,\"t\":%u,\"d\":%d}",
points[i].x, points[i].y, points[i].pressure,
points[i].timestamp_ms, points[i].pen_down);
}
/* JSON尾部 */
offset += snprintf(json_buf + offset, buf_size - offset, "]}");
return offset;
}
/**
* 将设备状态编码为JSON格式
* 格式: {"gateway_id":"xx","pen_id":"xx","event":"battery","value":85}
*/
static int encode_status_json(const char *pen_id_str,
const char *event_type,
int value, char *json_buf, int buf_size)
{
return snprintf(json_buf, buf_size,
"{\"gw\":\"%s\",\"pen\":\"%s\",\"event\":\"%s\","
"\"value\":%d,\"ts\":%lu}",
g_converter.gateway_id, pen_id_str, event_type,
value, (unsigned long)time(NULL));
}
/* ======================== 简单LZ压缩 ======================== */
/**
* 简易RLE压缩 - 对二进制负载进行行程编码压缩
* 当连续相同字节超过3个时进行压缩
* 返回压缩后长度，若压缩无效则返回原始长度
*/
static uint32_t rle_compress(const uint8_t *input, uint32_t input_len,
uint8_t *output, uint32_t output_max)
{
if (input_len < COMPRESS_THRESHOLD) {
/* 数据量太小，不压缩 */
memcpy(output, input, input_len);
return input_len;
}
uint32_t out_pos = 0;
uint32_t i = 0;
/* 写入压缩标记头 */
output[out_pos++] = 0x52; /* 'R' - RLE标记 */
output[out_pos++] = 0x4C; /* 'L' */
output[out_pos++] = (input_len >> 8) & 0xFF; /* 原始长度高字节 */
output[out_pos++] = input_len & 0xFF; /* 原始长度低字节 */
while (i < input_len && out_pos < output_max - 3) {
uint8_t current = input[i];
uint32_t run_len = 1;
/* 统计连续相同字节 */
while (i + run_len < input_len &&
input[i + run_len] == current &&
run_len < 255) {
run_len++;
}
if (run_len >= 4) {
/* RLE编码: 转义字节 + 重复次数 + 值 */
output[out_pos++] = 0xFF; /* 转义标记 */
output[out_pos++] = (uint8_t)run_len;
output[out_pos++] = current;
} else {
/* 直接拷贝非重复数据 */
for (uint32_t j = 0; j < run_len && out_pos < output_max; j++) {
if (current == 0xFF) {
/* 原始数据恰好是0xFF，需要转义 */
output[out_pos++] = 0xFF;
output[out_pos++] = 0x01;
output[out_pos++] = 0xFF;
} else {
output[out_pos++] = current;
}
}
}
i += run_len;
}
/* 如果压缩后更大，返回原始数据 */
if (out_pos >= input_len) {
memcpy(output, input, input_len);
return input_len;
}
return out_pos;
}
/* ======================== 核心转换接口 ======================== */
/**
* 初始化协议转换器
* 设置网关标识，清空序列号追踪
*/
int protocol_converter_init(const char *gateway_id, bool use_binary,
bool enable_compression)
{
memset(&g_converter, 0, sizeof(g_converter));
strncpy(g_converter.gateway_id, gateway_id,
sizeof(g_converter.gateway_id) - 1);
g_converter.use_binary_format = use_binary;
g_converter.compression_enabled = enable_compression;
g_converter.next_sequence = 1;
/* 初始化序列号追踪数组 */
memset(g_converter.last_ble_seq, 0xFF, sizeof(g_converter.last_ble_seq));
printf("[协议转换] 初始化完成, 网关=%s, 二进制=%d, 压缩=%d\n",
gateway_id, use_binary, enable_compression);
return 0;
}
/**
* 将MAC地址字节数组转换为字符串表示
*/
static void mac_to_string(const uint8_t mac[6], char *str, int str_len)
{
snprintf(str, str_len, "%02X:%02X:%02X:%02X:%02X:%02X",
mac[0], mac[1], mac[2], mac[3], mac[4], mac[5]);
}
/**
* 核心协议转换函数
* 将BLE原始帧转换为MQTT消息
*
* @param raw_ble_data BLE接收到的原始字节流
* @param raw_len 原始数据长度
* @param pen_index 笔在连接表中的索引(0-63)
* @param mqtt_msg 输出: 转换后的MQTT消息
* @return 0=成功, -1=帧无效, -2=重复帧, -3=转换失败
*/
int convert_ble_to_mqtt(const uint8_t *raw_ble_data, uint32_t raw_len,
uint8_t pen_index, mqtt_message_t *mqtt_msg)
{
/* 步骤1: 验证BLE帧 */
if (!validate_ble_frame(raw_ble_data, raw_len)) {
g_converter.error_count++;
return -1;
}
const ble_frame_header_t *header = (const ble_frame_header_t *)raw_ble_data;
const uint8_t *payload = raw_ble_data + sizeof(ble_frame_header_t);
/* 步骤2: 序列号去重 */
if (is_duplicate_frame(pen_index, header->sequence)) {
return -2;
}
/* 获取笔MAC地址字符串 */
char pen_id_str[20];
mac_to_string(header->pen_id, pen_id_str, sizeof(pen_id_str));
/* 步骤3: 根据帧类型进行协议转换 */
char json_buf[MAX_JSON_BUFFER];
int json_len = 0;
switch (header->frame_type) {
case BLE_FRAME_STROKE: {
/* 笔迹坐标帧 → MQTT笔迹数据消息 */
decoded_point_t points[MAX_BATCH_POINTS];
int num_points = parse_stroke_frame(payload, header->payload_len,
points, MAX_BATCH_POINTS);
if (num_points <= 0) {
return -3;
}
/* 构建MQTT Topic: pen/{gateway_id}/stroke */
snprintf(mqtt_msg->topic, sizeof(mqtt_msg->topic),
"pen/%s/stroke", g_converter.gateway_id);
/* 编码为JSON负载 */
json_len = encode_stroke_json(pen_id_str, points, num_points,
json_buf, sizeof(json_buf));
/* 笔迹数据使用QoS 1确保送达 */
mqtt_msg->qos = 1;
mqtt_msg->retain = false;
break;
}
case BLE_FRAME_PAGE_TURN: {
/* 翻页事件 → MQTT事件消息 */
uint16_t page_id = payload[0] | ((uint16_t)payload[1] << 8);
snprintf(mqtt_msg->topic, sizeof(mqtt_msg->topic),
"pen/%s/event", g_converter.gateway_id);
json_len = snprintf(json_buf, sizeof(json_buf),
"{\"gw\":\"%s\",\"pen\":\"%s\",\"event\":\"page_turn\","
"\"page_id\":%u,\"ts\":%lu}",
g_converter.gateway_id, pen_id_str, page_id,
(unsigned long)time(NULL));
mqtt_msg->qos = 1;
mqtt_msg->retain = false;
break;
}
case BLE_FRAME_PEN_STATE: {
/* 笔状态帧 → MQTT事件消息 */
const char *state = (payload[0] == 0x01) ? "pen_down" : "pen_up";
snprintf(mqtt_msg->topic, sizeof(mqtt_msg->topic),
"pen/%s/event", g_converter.gateway_id);
json_len = encode_status_json(pen_id_str, state,
payload[0], json_buf, sizeof(json_buf));
mqtt_msg->qos = 0;
mqtt_msg->retain = false;
break;
}
case BLE_FRAME_BATTERY: {
/* 电量上报帧 → MQTT状态消息 */
uint8_t battery_pct = payload[0];
snprintf(mqtt_msg->topic, sizeof(mqtt_msg->topic),
"gateway/%s/status", g_converter.gateway_id);
json_len = encode_status_json(pen_id_str, "battery",
battery_pct, json_buf, sizeof(json_buf));
/* 电量信息使用QoS 0，允许丢失 */
mqtt_msg->qos = 0;
mqtt_msg->retain = true; /* 保留最新电量 */
break;
}
case BLE_FRAME_HEARTBEAT: {
/* 心跳帧 → 更新设备在线状态，不转发至MQTT */
/* 心跳由设备管理器处理，此处仅记录 */
return 0;
}
default:
return -3;
}
/* 步骤4: 将JSON数据填入MQTT消息负载 */
if (json_len > 0 && json_len < (int)sizeof(mqtt_msg->payload)) {
if (g_converter.compression_enabled &&
json_len > COMPRESS_THRESHOLD) {
/* 压缩JSON负载 */
mqtt_msg->payload_len = rle_compress(
(const uint8_t *)json_buf, json_len,
mqtt_msg->payload, sizeof(mqtt_msg->payload));
} else {
memcpy(mqtt_msg->payload, json_buf, json_len);
mqtt_msg->payload_len = json_len;
}
}
mqtt_msg->msg_seq = allocate_msg_sequence();
g_converter.total_converted++;
return 0;
}
/**
* 将云端MQTT命令消息转换为BLE控制帧
* 支持命令类型：OTA触发、配置更新、校准指令
*
* @param mqtt_payload MQTT消息负载(JSON)
* @param payload_len 负载长度
* @param ble_cmd_buf 输出: BLE命令帧缓冲
* @param buf_size 缓冲区大小
* @return 生成的BLE命令帧长度, -1=失败
*/
int convert_mqtt_to_ble_command(const uint8_t *mqtt_payload,
uint32_t payload_len,
uint8_t *ble_cmd_buf, uint32_t buf_size)
{
/* 简易JSON解析 - 查找command字段 */
const char *json_str = (const char *)mqtt_payload;
const char *cmd_start = strstr(json_str, "\"command\":\"");
if (cmd_start == NULL) {
return -1;
}
cmd_start += strlen("\"command\":\"");
/* 构建BLE命令帧头 */
ble_frame_header_t *cmd_header = (ble_frame_header_t *)ble_cmd_buf;
cmd_header->sync_byte = 0xAA;
cmd_header->sequence = allocate_msg_sequence();
uint8_t *cmd_payload = ble_cmd_buf + sizeof(ble_frame_header_t);
uint16_t cmd_payload_len = 0;
if (strncmp(cmd_start, "ota_start", 9) == 0) {
/* OTA升级启动命令 */
cmd_header->frame_type = BLE_FRAME_OTA_ACK;
cmd_payload[0] = 0x01; /* OTA开始标记 */
cmd_payload_len = 1;
} else if (strncmp(cmd_start, "calibrate", 9) == 0) {
/* 校准命令 */
cmd_header->frame_type = BLE_FRAME_PEN_STATE;
cmd_payload[0] = 0x10; /* 校准指令码 */
cmd_payload_len = 1;
} else {
return -1;
}
cmd_header->payload_len = cmd_payload_len;
/* 追加CRC校验 */
uint32_t frame_len = sizeof(ble_frame_header_t) + cmd_payload_len;
uint16_t crc = crc16_ccitt(ble_cmd_buf, frame_len);
memcpy(ble_cmd_buf + frame_len, &crc, 2);
return frame_len + 2;
}
/**
* 获取协议转换器统计信息
*/
void protocol_converter_get_stats(uint32_t *converted,
uint32_t *dropped,
uint32_t *errors)
{
if (converted) *converted = g_converter.total_converted;
if (dropped) *dropped = g_converter.total_dropped;
if (errors) *errors = g_converter.error_count;
}
/**
* 重置协议转换器统计计数
*/
void protocol_converter_reset_stats(void)
{
g_converter.total_converted = 0;
g_converter.total_dropped = 0;
g_converter.error_count = 0;
printf("[协议转换] 统计计数已重置\n");
}