请给我一段用Stm32,HAL库编写，PC0脚，符合以下要求的完整代码。1. 使用电脑端串口调试助手控制板子上LED的亮度 2. 发送命令，可以设置LED指定的亮度 3. 发送命令，可以设置LED的亮度增加或减小多少 4. 要求LED的亮度通过PWM的方法进行控制

#include "stm32f1xx_hal.h"
#include <stdio.h>
#include "usart.h"

// LED PWM 定义
#define LED_PIN GPIO_PIN_0
#define LED_GPIO_PORT GPIOB
#define LED_PWM_CHANNEL RCC_APB2Periph_GPIOB

// PWM 参数
#define LED_MAX_DUTY_CYCLE 100
#define LED_MIN_DUTY_CYCLE 0
#define PWM FREQUENCY 5000

void led_PWM_Init(void) {
    RCC_AHB2PeriphClockCmd(LED_GPIO_PORT, ENABLE);
    GPIO_InitTypeDef GPIO_InitStructure;
    GPIO_InitStructure.GPIO_Pin = LED_PIN;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(LED_GPIO_PORT, &GPIO_InitStructure);

    // 初始化PWM
    TIM_HandleTypeDef htim;
    htim.Instance = TIM2; // 使用TIM2作为PWM定时器
    htim.Init.Prescaler = ((F_CPU / PWM) - 1) / 2; // 计算预分频值
    htim.Init.CounterMode = TIM_CounterMode_Up;
    htim.Init.Period = (PWM * LED_MAX_DUTY_CYCLE) / 100; // 设置周期
    HAL_TIM_PWM_Init(&htim); // 初始化PWM模式
    HAL_TIM_PWM_MspInit(&htim); // 配置PWM时钟和中断
}

void led_PWM_SetDutyCycle(uint8_t duty_cycle) {
    if (duty_cycle > LED_MAX_DUTY_CYCLE || duty_cycle < LED_MIN_DUTY_CYCLE) {
        printf("Invalid duty cycle! Must be between %d and %d.\n", LED_MIN_DUTY_CYCLE, LED_MAX_DUTY_CYCLE);
        return;
    }

    uint16_t period = (PWM * duty_cycle) / 100;
    htim.Instance->CCR1 = period;

    // Update PWM duty cycle
    HAL_TIM_PWM肮Update(&htim);
}

int main(void) {
    led_PWM_Init();

    while (1) {
        char command[10];
        int duty_increase = 0;

        // 从串口接收命令
        if (USART_GetData(USART2)) { // Assuming USART2 is connected to your PC serial port
            scanf("%s", command);

            // 解析命令
            if (!strcmp(command, "+10")) {
                duty_increase = 10;
            } else if (!strcmp(command, "-10")) {
                duty_increase = -10;
            } else if (sscanf(command, "%d", &duty_cycle) == 1) {
                // 设置LED亮度
                led_PWM_SetDutyCycle(duty_cycle + duty_increase);
            } else {
                printf("Unknown command! Use '+10', '-10', or specify a brightness value.\n");
            }
        }
        HAL_Delay(100); // 为了简化示例，这里每100ms更新一次PWM
    }
}