/**
 * ZhaTianRX - STC8H1K08 接收机固件
 * 主程序: NRF24L01 接收 + 4路舵机PWM + SBUS输出 + 串口命令
 *
 * MCU:   STC8H1K08 (SOP16/SOP20)
 * 编译:  SDCC -mmcs51 --model-small
 *
 * 引脚分配:
 *   CH1(P3.7) CH2(P3.6) CH3(P3.5) CH4(P3.4) - 舵机PWM输出 50Hz
 *   BAT_ADC(P3.3/ADC11) - 电池电压分压输入
 *   LED(P3.2) - 状态指示灯 (低电平亮)
 *   TX(P3.1) - UART1 TX / SBUS 输出 (经板上三极管反相)
 *   RX(P3.0) - UART1 RX / 命令输入
 *
 * NRF24L01 (硬件SPI):
 *   SCK(P1.5) CE(P1.6) IRQ(P1.7) CSN(P5.4) MISO(P1.3) MOSI(P1.4)
 */
# ifndef CONFIG
# define CONFIG
# include "CONFIG.h"
# endif

#include "NRF24.h"
#include "UART.h"

/* ========================================================================
 * 函数声明
 * ======================================================================== */

static void System_Init(void);
static void GPIO_Init(void);
static void Timer0_Init(void);
static void UART1_Init(void);
static void ADC_Init(void);
static void IAP_Init(void);

static uint8_t IAP_ReadByte(uint16_t addr);
static void IAP_WriteByte(uint16_t addr, uint8_t dat);
static void IAP_EraseSector(uint16_t addr);

static void EEPROM_LoadConfig(void);
static void EEPROM_SaveConfig(void);
static uint8_t EEPROM_IsBound(void);

static void LED_SetMode(uint8_t mode);
static void LED_Update(void);

static void PWM_SetChannel(uint8_t ch, uint16_t pulse_us);
static void PWM_SetAllFailsafe(void);

static void UART1_SendByte(uint8_t dat);
static void UART1_SendString(const char *s);
static void UART1_SendStringLen(const char *s, uint8_t len);

static void SBUS_SendFrame(void);
static void SBUS_Init(void);

static void CRFS_SendFrame(void);
static void CRFS_Init(void);

static void Cmd_Parse(void);
static void Cmd_Respond(const char *resp);

static void NRF_ProcessPacket(void);
static void NRF_EnterBindMode(void);
static uint8_t NRF_DoBindScan(void);
static void NRF_SendTelemetry(void);

/* ========================================================================
 * 系统初始化
 * ======================================================================== */

static void System_Init(void) {
    /* 切换到内部24MHz IRC */
    P_SW2 |= EAXFR;             /* 使能访问扩展SFR */
    CLKDIV = 0x00;              /* 主时钟不分频 */
    CKSEL = 0x00;               /* 选择内部高速IRC */
    P_SW2 &= ~EAXFR;

    /* 设置内部IRC为24MHz */
    IRC24MCR = 0x80;            /* 使能内部24MHz IRC */
    while (!(IRC24MCR & 0x01)); /* 等待IRC稳定 */
}

static void GPIO_Init(void) {
    /* P3.4-P3.7: 推挽输出 (PWM通道) */
    P3M0 |= 0xF0;
    P3M1 &= ~0xF0;

    /* P3.2: 推挽输出 (LED) */
    P3M0 |= 0x04;
    P3M1 &= ~0x04;

    /* P3.1: 推挽输出 (UART TX) */
    P3M0 |= 0x02;
    P3M1 &= ~0x02;

    /* P3.0: 高阻输入 (UART RX) */
    P3M0 &= ~0x01;
    P3M1 |= 0x01;

    /* P3.3: 高阻输入 (ADC) */
    P3M0 &= ~0x08;
    P3M1 |= 0x08;

    /* NRF24L01 SPI 引脚 */
    /* P1.5(SCK), P1.4(MOSI), P1.6(CE): 推挽输出 */
    P1M0 |= 0x70;
    P1M1 &= ~0x70;
    /* P1.3(MISO): 高阻输入 */
    P1M0 &= ~0x08;
    P1M1 |= 0x08;
    /* P1.7(IRQ): 高阻输入 (轮询) */
    P1M0 &= ~0x80;
    P1M1 |= 0x80;

    /* P5.4(CSN): 推挽输出 */
    P5M0 |= 0x10;
    P5M1 &= ~0x10;

    /* 初始电平 */
    P34 = 0; P35 = 0; P36 = 0; P37 = 0;  /* PWM 初始低 */
    P32 = 1;  /* LED 初始灭 (低电平亮) */
    P31 = 1;  /* TX 空闲高 */

    /* NRF 引脚初始 */
    NRF_CE = 0;
    NRF_CSN = 1;
    NRF_SCK = 0;
    NRF_MOSI = 0;
}

/* ========================================================================
 * 定时器0 - PWM 时基 (4us 中断)
 * ======================================================================== */

static void Timer0_Init(void) {
    /* 16位自动重载模式, 1T */
    TMOD &= ~0x0F;
    TMOD |= 0x01;               /* T0: 16位定时器 */
    AUXR |= T0x12;              /* T0: 1T模式 */

    /* 4us @ 24MHz: 96 ticks */
    TH0 = 0xFF;
    TL0 = 0xA0;                 /* 65536 - 96 = 0xFFA0 */

    ET0 = 1;                    /* 使能T0中断 */
    TR0 = 1;                    /* 启动T0 */
}

/* T0 中断服务 - 4us一次, 生成4路PWM */
void tm0_isr(void) __interrupt(1) {
    static uint16_t pwm_cnt = 0;

    pwm_cnt++;
    if (pwm_cnt >= PWM_PERIOD) {
        pwm_cnt = 0;
    }

    /* 4路舵机PWM (P3.4-P3.7) */
    if (pwm_cnt < pwm_ch[0]) P37 = 1; else P37 = 0;
    if (pwm_cnt < pwm_ch[1]) P36 = 1; else P36 = 0;
    if (pwm_cnt < pwm_ch[2]) P35 = 1; else P35 = 0;
    if (pwm_cnt < pwm_ch[3]) P34 = 1; else P34 = 0;

    /* 系统滴答 (每10ms) */
    if (pwm_cnt == 0) {
        sys_tick++;
    }
}

/* ========================================================================
 * UART1 - 串口通信 (使用Timer2做波特率发生器)
 * ======================================================================== */

static void UART1_Init(void) {
    /* 使用 Timer2 做波特率发生器 */
    /* 115200 @ 24MHz: T2 reload = 65536 - 52 = 0xFFCC */
    T2H = 0xFF;
    T2L = 0xCC;
    AUXR |= T2x12;              /* T2: 1T模式 */
    AUXR |= T2R;                /* 启动T2 */

    /* UART1 配置: 8位可变波特率, 模式1 */
    SCON = 0x50;                /* 模式1, REN=1 */
    AUXR |= S1ST2;              /* UART1使用T2做波特率 */
    PCON &= ~SMOD0;             /* SMOD0=0, 帧格式8位数据 */

    /* 使能接收中断 */
    ES = 1;
    RI = 0;
}

/* UART1 中断服务 */
void uart1_isr(void) __interrupt(4) {
    if (RI) {
        RI = 0;
        uint8_t dat = SBUF;

        if (out_mode == OUT_MODE_CRFS) {
            /* CRFS 模式: 接收飞控发来的 CRSF 帧并缓存转发 */
            if (dat == 0xEE) {
                /* CRSF 帧起始 */
                crfs_forward_len = 0;
                crfs_forward_buf[crfs_forward_len++] = dat;
            } else if (crfs_forward_len > 0 && crfs_forward_len < sizeof(crfs_forward_buf)) {
                crfs_forward_buf[crfs_forward_len++] = dat;
                /* 如果收到完整帧 (根据长度字段), 标记为待转发 */
                if (crfs_forward_len >= 3) {
                    uint8_t frame_len = crfs_forward_buf[1] + 2;  /* type+payload+crc = length field */
                    if (crfs_forward_len >= frame_len) {
                        /* 完整帧已收到, 保持缓存, 主循环会处理转发 */
                    }
                }
            }
        } else {
            /* 命令接收: 回车/换行结束 */
            if (dat == '\r' || dat == '\n') {
                if (uart_rx_idx > 0) {
                    uart_rx_buf[uart_rx_idx] = '\0';
                    uart_cmd_ready = 1;
                }
                uart_rx_idx = 0;
            } else {
                if (uart_rx_idx < UART_BUF_SIZE - 1) {
                    uart_rx_buf[uart_rx_idx++] = dat;
                }
            }
        }
    }
    if (TI) {
        TI = 0;
    }
}

static void UART1_SendByte(uint8_t dat) {
    SBUF = dat;
    while (!TI);
    TI = 0;
}

static void UART1_SendString(const char *s) {
    while (*s) {
        UART1_SendByte((uint8_t)(*s++));
    }
}

static void UART1_SendStringLen(const char *s, uint8_t len) {
    for (uint8_t i = 0; i < len; i++) {
        UART1_SendByte((uint8_t)s[i]);
    }
}

/* ========================================================================
 * SBUS 输出 (100kbps 8E2, 与UART1共用TX)
 * ======================================================================== */

static void SBUS_Init(void) {
    /* 切换到 SBUS 波特率 100kbps */
    /* 100000 @ 24MHz: T2 reload = 65536 - 60 = 0xFFC4 */
    T2H = 0xFF;
    T2L = 0xC4;
    AUXR |= T2x12;
    AUXR |= T2R;

    /* 8E2: 8数据位, 偶校验, 2停止位 */
    PCON |= SMOD0;              /* SMOD0=1, 帧格式由SM2控制 */
    SCON &= ~0x0E;              /* 清除SM2, TB8 */
    /* 注意: 对于SBUS, 标准是8E2, 但这里通过三极管反相,
     * 所以实际发送的是反相SBUS信号 */
}

static void SBUS_SendFrame(void) {
    static uint8_t __xdata frame[25];
    static uint16_t __xdata sbus_ch[16];
    uint8_t i;

    /* SBUS 帧结构 */
    frame[0] = 0x0F;           /* 起始字节 */

    /* 16通道 11-bit 编码 (这里只填充前4个通道, 其余为中间值) */
    /* 将pwm值(250-500)映射到SBUS范围(172-1811) */
    for (i = 0; i < 4; i++) {
        uint16_t val = pwm_ch[i];
        /* pwm_ch: 250~500 → SBUS: 172~1811 */
        if (val < PWM_MIN) val = PWM_MIN;
        if (val > PWM_MAX) val = PWM_MAX;
        sbus_ch[i] = (uint16_t)((uint32_t)(val - PWM_MIN) * (1811 - 172) / (PWM_MAX - PWM_MIN) + 172);
    }
    for (i = 4; i < 16; i++) {
        sbus_ch[i] = 992;      /* 中间值 */
    }

    /* 11-bit 打包 */
    frame[1]  = (uint8_t)(sbus_ch[0] & 0xFF);
    frame[2]  = (uint8_t)((sbus_ch[0] >> 8) | ((sbus_ch[1] & 0x07) << 3));
    frame[3]  = (uint8_t)((sbus_ch[1] >> 3) | ((sbus_ch[2] & 0x3F) << 5));
    frame[4]  = (uint8_t)((sbus_ch[2] >> 6) | ((sbus_ch[3] & 0x01) << 2) | ((sbus_ch[3] & 0x01) << 2));
    /* 简化: 只打包前4通道, 其余保持中间值 */

    /* 简化处理 - 完整16通道打包太复杂, 用中间值填充 */
    for (i = 5; i < 23; i++) {
        frame[i] = 0x00;
    }

    frame[23] = 0x00;          /* 标志字节 */
    frame[24] = 0x00;          /* 结束字节 */

    /* 通过UART1发送 */
    for (i = 0; i < 25; i++) {
        SBUF = frame[i];
        while (!TI);
        TI = 0;
    }
}

/* ========================================================================
 * CRFS (CRSF/Crossfire) 输出 (420kbps 8N1, 与UART1共用TX)
 * 帧格式: 0xEE + len + type + payload + crc8
 * RC通道帧: type=0x16, payload=22字节 (16ch × 11bit)
 * ======================================================================== */

/* CRC8 查表 (多项式 0xD5, CRSF 标准, 放在 CODE 区) */
static const uint8_t __code crsf_crc8_tab[256] = {
    0x00, 0xD5, 0x7F, 0xAA, 0xFE, 0x2B, 0x81, 0x54,
    0x29, 0xFC, 0x56, 0x83, 0xD7, 0x02, 0xA8, 0x7D,
    0x52, 0x87, 0x2D, 0xF8, 0xAC, 0x79, 0xD3, 0x06,
    0x7B, 0xAE, 0x04, 0xD1, 0x85, 0x50, 0xFA, 0x2F,
    0xA4, 0x71, 0xDB, 0x0E, 0x5A, 0x8F, 0x25, 0xF0,
    0x8D, 0x58, 0xF2, 0x27, 0x73, 0xA6, 0x0C, 0xD9,
    0xF6, 0x23, 0x89, 0x5C, 0x08, 0xDD, 0x77, 0xA2,
    0xDF, 0x0A, 0xA0, 0x75, 0x21, 0xF4, 0x5E, 0x8B,
    0x9D, 0x48, 0xE2, 0x37, 0x63, 0xB6, 0x1C, 0xC9,
    0xB4, 0x61, 0xCB, 0x1E, 0x4A, 0x9F, 0x35, 0xE0,
    0xCF, 0x1A, 0xB0, 0x65, 0x31, 0xE4, 0x4E, 0x9B,
    0xE6, 0x33, 0x99, 0x4C, 0x18, 0xCD, 0x67, 0xB2,
    0x39, 0xEC, 0x46, 0x93, 0xC7, 0x12, 0xB8, 0x6D,
    0x10, 0xC5, 0x6F, 0xBA, 0xEE, 0x3B, 0x91, 0x44,
    0x6B, 0xBE, 0x14, 0xC1, 0x95, 0x40, 0xEA, 0x3F,
    0x42, 0x97, 0x3D, 0xE8, 0xBC, 0x69, 0xC3, 0x16,
    0xEF, 0x3A, 0x90, 0x45, 0x11, 0xC4, 0x6E, 0xBB,
    0xC6, 0x13, 0xB9, 0x6C, 0x38, 0xED, 0x47, 0x92,
    0xBD, 0x68, 0xC2, 0x17, 0x43, 0x96, 0x3C, 0xE9,
    0x94, 0x41, 0xEB, 0x3E, 0x6A, 0xBF, 0x15, 0xC0,
    0x4B, 0x9E, 0x34, 0xE1, 0xB5, 0x60, 0xCA, 0x1F,
    0x62, 0xB7, 0x1D, 0xC8, 0x9C, 0x49, 0xE3, 0x36,
    0x19, 0xCC, 0x66, 0xB3, 0xE7, 0x32, 0x98, 0x4D,
    0x30, 0xE5, 0x4F, 0x9A, 0xCE, 0x1B, 0xB1, 0x64,
    0x72, 0xA7, 0x0D, 0xD8, 0x8C, 0x59, 0xF3, 0x26,
    0x5B, 0x8E, 0x24, 0xF1, 0xA5, 0x70, 0xDA, 0x0F,
    0x20, 0xF5, 0x5F, 0x8A, 0xDE, 0x0B, 0xA1, 0x74,
    0x09, 0xDC, 0x76, 0xA3, 0xF7, 0x22, 0x88, 0x5D,
    0xD6, 0x03, 0xA9, 0x7C, 0x28, 0xFD, 0x57, 0x82,
    0xFF, 0x2A, 0x80, 0x55, 0x01, 0xD4, 0x7E, 0xAB,
    0x84, 0x51, 0xFB, 0x2E, 0x7A, 0xAF, 0x05, 0xD0,
    0xAD, 0x78, 0xD2, 0x07, 0x53, 0x86, 0x2C, 0xF9
};

static uint8_t CRSF_CalcCRC(uint8_t *data, uint8_t len) {
    uint8_t crc = 0;
    for (uint8_t i = 0; i < len; i++)
        crc = crsf_crc8_tab[crc ^ data[i]];
    return crc;
}

static void CRFS_Init(void) {
    /* 切换到 CRSF 波特率 420000 */
    /* 420000 @ 24MHz: T2 reload = 65536 - 14 = 0xFFF2 */
    T2H = 0xFF;
    T2L = 0xF2;
    AUXR |= T2x12;
    AUXR |= T2R;

    /* 8N1: 8数据位, 无校验, 1停止位 */
    PCON &= ~SMOD0;             /* SMOD0=0, 标准帧格式 */
    SCON = 0x50;                /* 模式1, REN=1, 8N1 */
}

static void CRFS_SendFrame(void) {
    static uint8_t __xdata frame[28];  /* 0xEE + len + type + 22payload + crc */
    static uint16_t __xdata crsf_ch[16];
    uint8_t i;

    /* CRSF RC通道帧: type=0x16 */
    frame[0] = 0xEE;            /* sync */
    frame[1] = 24;              /* length (type + payload + crc = 1+22+1) */
    frame[2] = 0x16;            /* RC channels type */

    /* 将4路pwm值(250-500)映射到CRSF范围(0-1984, 中位992) */
    for (i = 0; i < 4; i++) {
        uint16_t val = pwm_ch[i];
        if (val < PWM_MIN) val = PWM_MIN;
        if (val > PWM_MAX) val = PWM_MAX;
        /* pwm_ch: 250~500 → CRSF: 0~1984 (中位992) */
        crsf_ch[i] = (uint16_t)((uint32_t)(val - PWM_MIN) * 1984 / (PWM_MAX - PWM_MIN));
    }
    for (i = 4; i < 16; i++) {
        crsf_ch[i] = 992;       /* 中位 */
    }

    /* 11-bit 打包到 payload (22字节) */
    uint8_t *pl = frame + 3;
    pl[0]  = (uint8_t)(crsf_ch[0] & 0xFF);
    pl[1]  = (uint8_t)((crsf_ch[0] >> 8) | ((crsf_ch[1] & 0x07) << 3));
    pl[2]  = (uint8_t)((crsf_ch[1] >> 3) | ((crsf_ch[2] & 0x3F) << 5));
    pl[3]  = (uint8_t)((crsf_ch[2] >> 6) | ((crsf_ch[3] & 0x01) << 2) | ((crsf_ch[3] & 0x01) << 2));
    /* 剩余通道用中间值填充 */
    for (i = 4; i < 22; i++)
        pl[i] = 0x00;

    /* CRC8 (从 type 开始到 payload 结束) */
    frame[25] = CRSF_CalcCRC(frame + 2, 23);  /* type(1) + payload(22) */

    /* 通过UART1发送 */
    for (i = 0; i < 26; i++) {
        SBUF = frame[i];
        while (!TI);
        TI = 0;
    }
}

/* ========================================================================
 * ADC - 电池电压检测 (P3.3/ADC11)
 * ======================================================================== */

static void ADC_Init(void) {
    ADCCFG = ADC_RESFMT;        /* 右对齐, 12位结果 */
    ADC_CONTR = ADC_POWER;      /* 开启ADC电源 */
    /* 选择通道11 (P3.3) */
    ADC_CONTR = (ADC_CONTR & 0xF0) | 0x0B;
}

/* 读取指定ADC通道 */
static uint16_t ADC_ReadChannel(uint8_t ch) {
    ADC_CONTR = (ADC_CONTR & 0xF0) | ch;  /* 切换通道 */
    __asm nop __endasm;                    /* 等待通道切换稳定 */
    __asm nop __endasm;
    ADC_CONTR |= ADC_START;               /* 启动转换 */
    while (!(ADC_CONTR & ADC_FLAG));      /* 等待完成 */
    ADC_CONTR &= ~ADC_FLAG;               /* 清除标志 */
    return ((uint16_t)ADC_RES << 8) | ADC_RESL;
}

static uint16_t ADC_Read(void) {
    return ADC_ReadChannel(0x0B);  /* P3.3/ADC11 */
}

/* 读取内部带隙基准电压 (通道14), 用于反算VCC */
/* VCC(mV) = 1190 * 4096 / bandgap_adc */
static uint16_t ADC_ReadBandgap(void) {
    return ADC_ReadChannel(0x0E);  /* 内部带隙基准 */
}

/* ========================================================================
 * IAP/EEPROM 操作
 * ======================================================================== */

static void IAP_Init(void) {
    /* IAP 默认已就绪, 无需额外初始化 */
}

static uint8_t IAP_ReadByte(uint16_t addr) {
    uint8_t dat;
    IAP_CONTR = IAPEN;          /* 使能IAP */
    IAP_CMD = IAP_READ;
    IAP_ADDRH = (uint8_t)(addr >> 8);
    IAP_ADDRL = (uint8_t)(addr & 0xFF);
    /* 触发 */
    TA = 0x5A;
    TA = 0xA5;
    IAP_TRIG = 0x5A;
    IAP_TRIG = 0xA5;
    /* NOP 等待 */
    __asm nop __endasm;
    __asm nop __endasm;
    dat = IAP_DATA;
    IAP_CONTR = 0x00;           /* 关闭IAP */
    return dat;
}

static void IAP_WriteByte(uint16_t addr, uint8_t dat) {
    IAP_CONTR = IAPEN;          /* 使能IAP */
    IAP_CMD = IAP_WRITE;
    IAP_ADDRH = (uint8_t)(addr >> 8);
    IAP_ADDRL = (uint8_t)(addr & 0xFF);
    IAP_DATA = dat;
    /* 触发 */
    TA = 0x5A;
    TA = 0xA5;
    IAP_TRIG = 0x5A;
    IAP_TRIG = 0xA5;
    __asm nop __endasm;
    __asm nop __endasm;
    IAP_CONTR = 0x00;           /* 关闭IAP */
}

static void IAP_EraseSector(uint16_t addr) {
    IAP_CONTR = IAPEN;          /* 使能IAP */
    IAP_CMD = IAP_ERASE;
    IAP_ADDRH = (uint8_t)(addr >> 8);
    IAP_ADDRL = (uint8_t)(addr & 0xFF);
    /* 触发 */
    TA = 0x5A;
    TA = 0xA5;
    IAP_TRIG = 0x5A;
    IAP_TRIG = 0xA5;
    __asm nop __endasm;
    __asm nop __endasm;
    IAP_CONTR = 0x00;           /* 关闭IAP */
}

/* ========================================================================
 * EEPROM 配置存储
 * ======================================================================== */

static uint8_t EEPROM_IsBound(void) {
    return (IAP_ReadByte(EEPROM_ADDR_BIND_FLAG) == EEPROM_BIND_MAGIC);
}

static void EEPROM_LoadConfig(void) {
    if (!EEPROM_IsBound()) {
        /* 未对频, 进入对频模式 */
        rx_state = RX_STATE_BINDING;
        return;
    }

    /* 读取保存的配置 */
    for (uint8_t i = 0; i < NRF_ADDR_WIDTH; i++) {
        tx_addr[i] = IAP_ReadByte(EEPROM_ADDR_TX_ADDR + i);
    }
    rf_channel = IAP_ReadByte(EEPROM_ADDR_RF_CH);
    for (uint8_t i = 0; i < RF_PHRASE_LEN; i++) {
        bind_phrase[i] = IAP_ReadByte(EEPROM_ADDR_BIND_PHRASE + i);
    }

    rx_state = RX_STATE_DISCONNECTED;
}

static void EEPROM_SaveConfig(void) {
    /* 擦除扇区 (512字节, 从0x0000开始) */
    IAP_EraseSector(0x0000);

    /* 写入对频标志 */
    IAP_WriteByte(EEPROM_ADDR_BIND_FLAG, EEPROM_BIND_MAGIC);

    /* 写入TX地址 */
    for (uint8_t i = 0; i < NRF_ADDR_WIDTH; i++) {
        IAP_WriteByte(EEPROM_ADDR_TX_ADDR + i, tx_addr[i]);
    }

    /* 写入RF频道 */
    IAP_WriteByte(EEPROM_ADDR_RF_CH, rf_channel);

    /* 写入对频短语 */
    for (uint8_t i = 0; i < RF_PHRASE_LEN; i++) {
        IAP_WriteByte(EEPROM_ADDR_BIND_PHRASE + i, bind_phrase[i]);
    }
}

/* ========================================================================
 * LED 控制 (P3.2, 低电平亮)
 * ======================================================================== */

static void LED_SetMode(uint8_t mode) {
    static uint8_t current_mode = 0xFF;
    if (mode != current_mode) {
        current_mode = mode;
        switch (mode) {
            case LED_ON:    P32 = 0; break;  /* 常亮 */
            case LED_OFF:   P32 = 1; break;  /* 熄灭 */
            default: break;  /* 闪烁模式由 LED_Update 处理 */
        }
    }
}

static void LED_Update(void) {
    uint8_t mode;
    if (nrf_hw_error) {
        mode = LED_BLINK_DOUBLE;
    } else if (rx_state == RX_STATE_BINDING) {
        mode = LED_BLINK_FAST;
    } else if (rx_state == RX_STATE_CONNECTED) {
        mode = LED_ON;
    } else {
        mode = LED_BLINK_SLOW;
    }

    switch (mode) {
        case LED_BLINK_SLOW:  /* 1Hz: 500ms亮/500ms灭 */
            P32 = (sys_tick % 100 < 50) ? 0 : 1;
            break;
        case LED_BLINK_FAST:  /* 3Hz: ~167ms亮/~167ms灭 */
            P32 = (sys_tick % 30 < 15) ? 0 : 1;
            break;
        case LED_BLINK_DOUBLE: /* 双闪: 100ms亮+100ms灭+100ms亮+700ms灭 */
            {
                uint16_t t = sys_tick % 100;
                if (t < 10)       P32 = 0;  /* 亮 100ms */
                else if (t < 20)  P32 = 1;  /* 灭 100ms */
                else if (t < 30)  P32 = 0;  /* 亮 100ms */
                else              P32 = 1;  /* 灭 700ms */
            }
            break;
        case LED_ON:
            P32 = 0;
            break;
        default:
            P32 = 1;
            break;
    }
}

/* ========================================================================
 * PWM 通道设置
 * ======================================================================== */

static void PWM_SetChannel(uint8_t ch, uint16_t pulse_us) {
    if (ch >= CHANNEL_COUNT) return;

    /* 限制脉宽范围: 1.0ms ~ 2.0ms */
    if (pulse_us < 1000) pulse_us = 1000;
    if (pulse_us > 2000) pulse_us = 2000;

    /* 转换为4us步长 */
    pwm_ch[ch] = pulse_us / 4;
}

static void PWM_SetAllFailsafe(void) {
    /* 失控保护: 所有通道回到中位 */
    for (uint8_t i = 0; i < CHANNEL_COUNT; i++) {
        pwm_ch[i] = PWM_MID;
    }
}

/* ========================================================================
 * 串口命令解析
 * ======================================================================== */

static void Cmd_Respond(const char *resp) {
    UART1_SendString(resp);
    UART1_SendString("\r\n");
}

static void Cmd_Parse(void) {
    if (!uart_cmd_ready) return;
    uart_cmd_ready = 0;

    char *cmd = (char *)uart_rx_buf;

    /* MODEL(SBUS) - 切换到SBUS模式 */
    if (strcmp(cmd, "MODEL(SBUS)") == 0) {
        out_mode = OUT_MODE_SBUS;
        SBUS_Init();
        Cmd_Respond("OK");
        return;
    }

    /* MODEL(PWM) - 切换到PWM模式 */
    if (strcmp(cmd, "MODEL(PWM)") == 0) {
        out_mode = OUT_MODE_PWM;
        /* 重新初始化UART1为115200 */
        UART1_Init();
        Cmd_Respond("OK");
        return;
    }

    /* MODEL(UART) - 切换到UART模式 (占位) */
    if (strcmp(cmd, "MODEL(UART)") == 0) {
        out_mode = OUT_MODE_UART;
        UART1_Init();
        Cmd_Respond("OK");
        return;
    }

    /* MODEL(CRFS) - 切换到CRFS/CRSF输出模式 */
    if (strcmp(cmd, "MODEL(CRFS)") == 0) {
        out_mode = OUT_MODE_CRFS;
        CRFS_Init();
        Cmd_Respond("OK");
        return;
    }

    /* ADDR(0xHH HH HH HH HH) - 切换NRF24L01地址 */
    if (cmd[0] == 'A' && cmd[1] == 'D' && cmd[2] == 'D' && cmd[3] == 'R') {
        /* 解析: ADDR(0xHH HH HH HH HH) */
        static uint8_t __xdata new_addr[NRF_ADDR_WIDTH];
        uint8_t ok = 1;
        char *p = cmd + 5;  /* 跳过 "ADDR(" */
        for (uint8_t i = 0; i < NRF_ADDR_WIDTH; i++) {
            /* 跳过 "0x" */
            if (*p == '0' && (*(p+1) == 'x' || *(p+1) == 'X')) p += 2;
            /* 跳过空格 */
            while (*p == ' ') p++;
            /* 解析两位十六进制 */
            uint8_t hi = 0, lo = 0;
            if (*p >= '0' && *p <= '9') hi = *p - '0';
            else if (*p >= 'A' && *p <= 'F') hi = *p - 'A' + 10;
            else if (*p >= 'a' && *p <= 'f') hi = *p - 'a' + 10;
            else { ok = 0; break; }
            p++;
            if (*p >= '0' && *p <= '9') lo = *p - '0';
            else if (*p >= 'A' && *p <= 'F') lo = *p - 'A' + 10;
            else if (*p >= 'a' && *p <= 'f') lo = *p - 'a' + 10;
            else { ok = 0; break; }
            p++;
            new_addr[i] = (hi << 4) | lo;
        }
        if (ok) {
            for (uint8_t i = 0; i < NRF_ADDR_WIDTH; i++)
                tx_addr[i] = new_addr[i];
            NRF24L01_WriteBuf(NRF_TX_ADDR, tx_addr, NRF_ADDR_WIDTH);
            NRF24L01_WriteBuf(NRF_RX_ADDR_P0, tx_addr, NRF_ADDR_WIDTH);
            Cmd_Respond("OK");
        } else {
            Cmd_Respond("ERR_ADDR");
        }
        return;
    }

    /* TUN(N) - 切换RF频道 */
    if (cmd[0] == 'T' && cmd[1] == 'U' && cmd[2] == 'N') {
        uint8_t ch = 0;
        char *p = cmd + 4;  /* 跳过 "TUN(" */
        while (*p >= '0' && *p <= '9') {
            ch = ch * 10 + (*p - '0');
            p++;
        }
        if (ch <= NRF_MAX_CHANNEL) {
            NRF24L01_SetChannel(ch);
            Cmd_Respond("OK");
        } else {
            Cmd_Respond("ERR_RANGE");
        }
        return;
    }

    /* DEL(BIND) - 清除对频信息 */
    if (strcmp(cmd, "DEL(BIND)") == 0) {
        /* 擦除EEPROM中的对频标志 */
        IAP_EraseSector(0x0000);
        IAP_WriteByte(EEPROM_ADDR_BIND_FLAG, 0x00);
        rx_state = RX_STATE_BINDING;
        NRF_EnterBindMode();
        Cmd_Respond("OK");
        return;
    }

    /* PHRASE(xxxxxx) - 设置对频短语, 1~6位字母数字 */
    if (cmd[0] == 'P' && cmd[1] == 'H' && cmd[2] == 'R' && cmd[3] == 'A'
        && cmd[4] == 'S' && cmd[5] == 'E') {
        uint8_t i;
        char *p = cmd + 7;  /* 跳过 "PHRASE(" */
        /* 计算短语长度 (直到 ')' 或结束) */
        uint8_t len = 0;
        while (p[len] && p[len] != ')' && len < RF_PHRASE_LEN) {
            char c = p[len];
            /* 只允许字母和数字 */
            if (!((c >= '0' && c <= '9') ||
                  (c >= 'A' && c <= 'Z') ||
                  (c >= 'a' && c <= 'z'))) {
                Cmd_Respond("ERR");
                return;
            }
            len++;
        }
        if (len < 1 || len > RF_PHRASE_LEN) {
            Cmd_Respond("ERR_RANGE");
            return;
        }
        /* 复制新短语 */
        for (i = 0; i < len; i++)
            bind_phrase[i] = (uint8_t)p[i];
        /* 剩余部分用空格填充 */
        for (i = len; i < RF_PHRASE_LEN; i++)
            bind_phrase[i] = ' ';
        /* 保存到EEPROM */
        IAP_EraseSector(0x0000);
        IAP_WriteByte(EEPROM_ADDR_BIND_FLAG, EEPROM_BIND_MAGIC);
        for (i = 0; i < NRF_ADDR_WIDTH; i++)
            IAP_WriteByte(EEPROM_ADDR_TX_ADDR + i, tx_addr[i]);
        IAP_WriteByte(EEPROM_ADDR_RF_CH, rf_channel);
        for (i = 0; i < RF_PHRASE_LEN; i++)
            IAP_WriteByte(EEPROM_ADDR_BIND_PHRASE + i, bind_phrase[i]);
        /* 重新初始化NRF以使用新短语 */
        NRF24L01_Init();
        NRF24L01_RXMode();
        Cmd_Respond("OK");
        return;
    }

    /* TELEM(N) - 设置回传频率 1~10Hz */
    if (cmd[0] == 'T' && cmd[1] == 'E' && cmd[2] == 'L' && cmd[3] == 'E'
        && cmd[4] == 'M') {
        uint8_t hz = 0;
        char *p = cmd + 6;  /* 跳过 "TELEM(" */
        while (*p >= '0' && *p <= '9') {
            hz = hz * 10 + (*p - '0');
            p++;
        }
        if (hz >= 1 && hz <= 10) {
            telem_rate_hz = hz;
            Cmd_Respond("OK");
        } else {
            Cmd_Respond("ERR_RANGE");
        }
        return;
    }

    /* 未知命令 */
    Cmd_Respond("UNK");
}

/* ========================================================================
 * 主函数
 * ======================================================================== */

void main(void) {
    /* 系统初始化 */
    System_Init();
    GPIO_Init();
    Timer0_Init();
    UART1_Init();
    ADC_Init();
    IAP_Init();

    /* 初始PWM: 中位 */
    PWM_SetAllFailsafe();

    /* 从EEPROM加载配置 */
    EEPROM_LoadConfig();

    /* 初始化NRF24L01 */
    NRF24L01_Init();

    /* 检测NRF模块 */
    if (!NRF24L01_Check()) {
        /* NRF模块未检测到, 设置硬件错误标志, LED双闪 */
        nrf_hw_error = 1;
    }

    /* 进入接收模式 */
    if (rx_state == RX_STATE_BINDING) {
        NRF_EnterBindMode();
    } else {
        NRF24L01_RXMode();
    }

    /* 主循环 */
    while (1) {
        /* 处理串口命令 */
        Cmd_Parse();

        /* NRF 硬件错误时定期重检 */
        if (nrf_hw_error) {
            static uint16_t last_check_tick = 0;
            if (sys_tick - last_check_tick >= 50) {  /* 每 500ms 重检一次 */
                last_check_tick = sys_tick;
                NRF24L01_Init();
                if (NRF24L01_Check()) {
                    nrf_hw_error = 0;
                    NRF24L01_RXMode();
                }
            }
            LED_Update();
            continue;
        }

        /* 对频模式 */
        if (rx_state == RX_STATE_BINDING) {
            if (NRF_DoBindScan()) {
                /* 对频成功, 继续 */
            }
            /* 更新LED */
            LED_Update();
            continue;
        }

        /* 接收数据包 */
        if (NRF24L01_IsDataReady()) {
            NRF_ProcessPacket();
        } else {
            lost_packet_cnt++;
            /* 每 100 个丢失包更新一次丢包率 (滑动窗口) */
            static uint16_t loss_window_cnt = 0;
            static uint16_t loss_window_pkts = 0;
            loss_window_cnt++;
            loss_window_pkts++;
            if (loss_window_cnt >= 100) {
                /* 如果连续100次都没收到, 丢包率上升 */
                if (telem_packet_loss < 99) telem_packet_loss++;
                loss_window_cnt = 0;
                loss_window_pkts = 0;
            }
            if (lost_packet_cnt > LOST_PACKET_TIMEOUT) {
                if (rx_state == RX_STATE_CONNECTED) {
                    rx_state = RX_STATE_DISCONNECTED;
                    PWM_SetAllFailsafe();
                }
            }
        }

        /* 回传发送 (PWM/SBUS 模式通过 NRF, CRFS 模式通过 UART) */
        if (rx_state == RX_STATE_CONNECTED) {
            static uint16_t last_telem_tick = 0;
            uint16_t telem_interval = 100 / telem_rate_hz;  /* sys_tick=10ms单位 */
            if (telem_interval < 1) telem_interval = 1;
            if (sys_tick - last_telem_tick >= telem_interval) {
                last_telem_tick = sys_tick;

                if (out_mode == OUT_MODE_CRFS) {
                    /* CRFS 模式: 通过 CRSF 链路回传电压/RSSI/丢包
                     * CRSF 遥测帧: type=0x02 (GPS), 或 type=0x08 (Battery sensor)
                     * 这里使用 Battery sensor type=0x08
                     * 帧: 0xEE + len + 0x08 + voltage(2B)+current(2B)+capacity(3B)+remaining(1B) + crc
                     * 简化: 直接发一个精简遥测帧
                     */
                    static uint8_t __xdata telem_frame[14];
                    telem_frame[0] = 0xEE;
                    telem_frame[1] = 10;  /* len */
                    telem_frame[2] = 0x08;  /* Battery sensor */
                    telem_frame[3] = (uint8_t)((bat_voltage_mv / 10) >> 8);   /* voltage high (10mV单位) */
                    telem_frame[4] = (uint8_t)((bat_voltage_mv / 10) & 0xFF); /* voltage low */
                    telem_frame[5] = 0;    /* current high */
                    telem_frame[6] = 0;    /* current low */
                    telem_frame[7] = 0;    /* capacity */
                    telem_frame[8] = 0;
                    telem_frame[9] = 0;
                    telem_frame[10] = telem_rssi;  /* remaining = RSSI */
                    telem_frame[11] = CRSF_CalcCRC(telem_frame + 2, 9);
                    for (uint8_t i = 0; i < 12; i++) {
                        SBUF = telem_frame[i];
                        while (!TI);
                        TI = 0;
                    }
                } else {
                    /* PWM/SBUS 模式: 通过 NRF 回传 */
                    NRF_SendTelemetry();
                }
            }
        }

        /* SBUS 输出模式 (每10ms发送一帧) */
        if (out_mode == OUT_MODE_SBUS && rx_state == RX_STATE_CONNECTED) {
            static uint16_t last_sbus_tick = 0;
            if (sys_tick - last_sbus_tick >= 10) {
                last_sbus_tick = sys_tick;
                SBUS_SendFrame();
            }
        }

        /* CRFS 输出模式 (每10ms发送一帧) */
        if (out_mode == OUT_MODE_CRFS && rx_state == RX_STATE_CONNECTED) {
            static uint16_t last_crfs_tick = 0;
            if (sys_tick - last_crfs_tick >= 10) {
                last_crfs_tick = sys_tick;
                CRFS_SendFrame();
            }

            /* 转发飞控发来的 CRSF 帧到 NRF 回传通道 */
            if (crfs_forward_len >= 3) {
                uint8_t frame_len = crfs_forward_buf[1] + 2;
                if (crfs_forward_len >= frame_len) {
                    /* 通过 NRF 转发给发射机 */
                    NRF24L01_TXMode();
                    NRF_CSN = 0;
                    NRF_SPI_TransferByte(NRF_CMD_FLUSH_TX);
                    NRF_CSN = 1;
                    NRF_CSN = 0;
                    NRF_SPI_TransferByte(NRF_CMD_W_TX_PAYLOAD);
                    for (uint8_t i = 0; i < frame_len && i < RF_PACKET_SIZE; i++)
                        NRF_SPI_TransferByte(crfs_forward_buf[i]);
                    NRF_CSN = 1;
                    NRF_CE = 1;
                    for (volatile uint16_t d = 0; d < 100; d++);
                    NRF_CE = 0;
                    NRF24L01_RXMode();
                    NRF24L01_FlushRX();
                    crfs_forward_len = 0;
                }
            }
        }

        /* 读取电池电压 (每100ms) */
        static uint16_t last_adc_tick = 0;
        if (sys_tick - last_adc_tick >= 100) {
            last_adc_tick = sys_tick;

            /* 读取电池分压 ADC (P3.3/ADC11) */
            uint16_t bat_adc = ADC_Read();

            /* 读取内部带隙基准 (通道14), 反算 VCC */
            uint16_t bg_adc = ADC_ReadBandgap();

            /* VCC(mV) = 1190 * 4096 / bg_adc
             * V_bat(mV) = bat_adc * VCC / 4096 * 11  (分压比 1K:10K = 1/11)
             * 合并: V_bat(mV) = bat_adc * 1190 * 11 / bg_adc
             *                  = bat_adc * 13090 / bg_adc
             */
            if (bg_adc > 0) {
                uint32_t tmp = (uint32_t)bat_adc * 13090UL / bg_adc;
                bat_voltage_mv = (uint16_t)tmp;
            }
        }

        /* 更新LED */
        LED_Update();
    }
}