串口输出帧：Out_Frame 结构、DMA 发送与 MATLAB 解析¶

typedef struct {
    u32   head;       // 帧头 (0x56aa55aa / 0x57aa55aa / 0x58aa55aa)
    float t;          // 时间戳 (s)
    float Gyro[3];    // 陀螺原始值 (deg/s)
    float Accel[3];   // 加计原始值 (m/s2, ×9.8)
    float Magn[3];    // 磁力计值 (μT, 带ASA修正)
    float mBar;       // 气压 (hPa)
    float Att[3];     // 姿态角 [pitch, roll, yaw] (rad)
    float Vn[3];      // 速度 [vE, vN, vU] (m/s)
    float Pos[5];      // 位置 [lat_deg, lat_frac, lon_deg, lon_frac, h]
    float GPS_Vn[3];  // GPS 速度 [vE, vN, vU] (m/s)
    float GPS_Pos[5]; // GPS 位置 [lat_deg, lat_frac, lon_deg, lon_frac, h]
    float GPS_status; // GPS 状态 = numSV + pDOP/100
    float GPS_delay;  // GPS 延迟 (s)
    float Temp;       // MPU9250 温度 (degC)
    u32   chksum;     // 校验和
} Out_Frame;

// usart.c L62-73
outFrame.t = (float)(MCU_ms_cnt / 1000.0f);                  // 时间 (s)

outFrame.Gyro[0] = (float)mpu_Data_value.Gyro[0];            // deg/s
outFrame.Gyro[1] = (float)mpu_Data_value.Gyro[1];
outFrame.Gyro[2] = (float)mpu_Data_value.Gyro[2];

outFrame.Accel[0] = (float)(mpu_Data_value.Accel[0] * 9.8f); // g→m/s2
outFrame.Accel[1] = (float)(mpu_Data_value.Accel[1] * 9.8f);
outFrame.Accel[2] = (float)(mpu_Data_value.Accel[2] * 9.8f);

outFrame.Magn[0] = (float)mpu_Data_value.Mag[0];             // μT
outFrame.Magn[1] = (float)mpu_Data_value.Mag[1];
outFrame.Magn[2] = (float)mpu_Data_value.Mag[2];

outFrame.mBar = (float)mpu_Data_value.Pressure;              // hPa

// usart.c L77-108
if(GPS_send_once == 1)
{
    outFrame.GPS_Vn[0] = (float)gps_Data_value.GPS_Vn[0];     // m/s
    outFrame.GPS_Vn[1] = (float)gps_Data_value.GPS_Vn[1];
    outFrame.GPS_Vn[2] = (float)gps_Data_value.GPS_Vn[2];

    // 经纬度拆成"整数度 + 小数度"两段
    Data_D = gps_Data_value.GPS_Pos[1] / DEG1;   // lon (rad → deg)
    Data_U = (u32)Data_D;                          // 整数度
    Data_F = (float)(Data_D - (double)Data_U);    // 小数度
    outFrame.GPS_Pos[0] = (float)Data_U;          // lon 整数
    outFrame.GPS_Pos[1] = Data_F;                  // lon 小数

    Data_D = gps_Data_value.GPS_Pos[0] / DEG1;   // lat (rad → deg)
    Data_U = (u32)Data_D;
    Data_F = (float)(Data_D - (double)Data_U);
    outFrame.GPS_Pos[2] = (float)Data_U;          // lat 整数
    outFrame.GPS_Pos[3] = Data_F;                  // lat 小数

    outFrame.GPS_Pos[4] = (float)gps_Data_value.GPS_Pos[2];  // h (m)

    // GPS 状态 = numSV + pDOP/100
    outFrame.GPS_status = (float)GPS_numSV + GPS_pDOP / 100.0f;

    // GPS 延迟
    outFrame.GPS_delay = GPS_Delay / 10000.0f;   // 100μs → s
    // ... 延迟修正见 04 篇

    GPS_send_once = 0;
}
else
{
    // GPS 无新数据时清零所有 GPS 字段
    outFrame.GPS_Vn[0..2] = 0;
    outFrame.GPS_Pos[0..4] = 0;
    outFrame.GPS_status = 0;
    outFrame.GPS_delay = 0;
}

// usart.c L119-121
for(outFrame.chksum = 0, pcheck = (u8*)&outFrame.t;
    pcheck < (u8*)&outFrame.chksum;
    pcheck++)
{
    outFrame.chksum += *pcheck;
}

void USART1_DIA_OUT_Configuration(void)
{
    DMA_InitTypeDef DMA_InitStructure;
    DMA_DeInit(DMA2_Stream7);
    DMA_InitStructure.DMA_Channel = DMA_Channel_4;
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&USART1->DR;  // 目标: USART1 数据寄存器
    DMA_InitStructure.DMA_Memory0BaseAddr = (uint32_t)&outFrame;       // 源: outFrame 结构体
    DMA_InitStructure.DMA_DIR = DMA_DIR_MemoryToPeripheral;             // 内存→外设
    DMA_InitStructure.DMA_BufferSize = (uint16_t)sizeof(outFrame);     // 140 字节
    DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;   // 外设地址不递增
    DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;             // 内存地址递增
    DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Byte;
    DMA_InitStructure.DMA_MemoryDataSize = DMA_PeripheralDataSize_Byte;
    DMA_InitStructure.DMA_Mode = DMA_Mode_Normal;                       // 单次模式
    DMA_InitStructure.DMA_Priority = DMA_Priority_High;
    DMA_Init(DMA2_Stream7, &DMA_InitStructure);
    USART_DMACmd(USART1, USART_DMAReq_Tx, ENABLE);
    USART_ClearFlag(USART1, USART_FLAG_TC);
    DMA_Cmd(DMA2_Stream7, ENABLE);
}

// TIM2 中断 (100 Hz)
if(MCU_ms_cnt > 10 && mcu_init_gpscfg == 0)
{
    Uart1_Out_Frame();              // 1. 打包上一帧数据到 outFrame
    USART1_DIA_OUT_Configuration();  // 2. 启动 DMA 发送 outFrame
}

Delay(0);                            // 3. 清零 totalDly

READ_MPU9250_A_T_G();               // 4. 读新数据
READ_MPU9250_MAG();
GAMT_OK_flag = 1;                   // 5. 通知主循环

outFrame.head = 0x56aa55aa;  // Mahony 模式
outFrame.head = 0x57aa55aa;  // SINSGPS 静态
outFrame.head = 0x58aa55aa;  // SINSGPS 动态

// Mahony 模式
AVPUartOut(q2att(mahony.qnb));  // 四元数→欧拉角→outFrame.Att

// SINS 模式
AVPUartOut(kf);  // KF 状态→outFrame.Att/Vn/Pos

% 1. 找帧头
header = fread(s, 4, 'uint32');
while header ~= hex2dec('56aa55aa') && ...
      header ~= hex2dec('57aa55aa') && ...
      header ~= hex2dec('58aa55aa')
    header = fread(s, 1, 'uint32');
end

% 2. 读剩余 136 字节
data = fread(s, 136/4, 'single');  % float32 数组

% 3. 解析字段
t       = data(1);
gyro    = data(2:4);     % deg/s
accel   = data(5:7);     % m/s2
mag     = data(8:10);    % μT
mBar    = data(11);
att     = data(12:14);   % pitch, roll, yaw (rad)
vn      = data(15:17);   % vE, vN, vU (m/s)
pos     = data(18:22);   % lon_int, lon_frac, lat_int, lat_frac, h
gps_vn  = data(23:25);
gps_pos = data(26:30);
gps_st  = data(31);
gps_dly = data(32);
temp    = data(33);
chksum  = fread(s, 1, 'uint32');

% 4. 校验
calc_chk = sum(typecast(single(data), 'uint8'), 'uint32');
assert(calc_chk == chksum);