嵌入式stm32f10x，编写基于PWM输出程序，占空比可调，步进为10%，频率由按键控制在100Hz到1KHz范围内调整，并能在屏幕上显示输出频率和占空比。 可由DMA方式实现占空比可调，此时不需要显示占空比

好的，这是一个关于嵌入式系统的问题。为了实现这个功能，你需要掌握以下知识点：

1. STM32F10x的PWM输出模块

2. 按键输入的扫描和处理

3. 显示模块的驱动

4. DMA传输的使用方法

下面是一个简单的实现步骤：

1. 初始化PWM输出模块，设置PWM的频率和占空比为初始值。

2. 初始化按键输入，设置按键扫描周期和处理函数。

3. 初始化显示模块，设置显示区域和字体等参数。

4. 通过按键调节PWM的频率和占空比。

5. 如果使用DMA方式实现占空比可调，需要在PWM输出模块中开启DMA传输。

6. 如果需要在屏幕上显示输出频率和占空比，可以通过显示模块实现。

7. 最后，无限循环等待按键输入或DMA传输完成。

关于具体的实现细节和代码实现，我可以提供一些参考：

1. PWM输出模块的初始化代码：

#include "stm32f10x.h"

void PWM_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStruct;
    TIM_OCInitTypeDef TIM_OCInitStruct;
    
    // Enable TIM3 clock
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
    
    // Enable GPIOB clock
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);
    
    // Configure PB0 as alternate function push-pull
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOB, &GPIO_InitStructure);
    
    // Configure TIM3 as PWM mode 1
    TIM_TimeBaseInitStruct.TIM_Period = 999; // PWM frequency = 72MHz / (Period + 1)
    TIM_TimeBaseInitStruct.TIM_Prescaler = 71; // PWM frequency = 72MHz / (Period + 1) / (Prescaler + 1)
    TIM_TimeBaseInitStruct.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseInitStruct.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseInitStruct);
    
    // Configure PWM output
    TIM_OCInitStruct.TIM_OCMode = TIM_OCMode_PWM1;
    TIM_OCInitStruct.TIM_OutputState = TIM_OutputState_Enable;
    TIM_OCInitStruct.TIM_Pulse = 500; // Duty cycle = Pulse / (Period + 1)
    TIM_OCInitStruct.TIM_OCPolarity = TIM_OCPolarity_High;
    TIM_OC1Init(TIM3, &TIM_OCInitStruct);
    
    TIM_Cmd(TIM3, ENABLE);
}

2. 按键输入的处理函数：

#include "stm32f10x.h"

volatile uint32_t g_button_pressed = 0;
volatile uint32_t g_pwm_frequency = 100; // PWM frequency in Hz
volatile uint32_t g_pwm_duty_cycle = 50; // PWM duty cycle in %

void EXTI0_IRQHandler(void)
{
    if (EXTI_GetITStatus(EXTI_Line0) != RESET)
    {
        g_button_pressed = 1;
        EXTI_ClearITPendingBit(EXTI_Line0);
    }
}

void Button_Scan(void)
{
    static uint32_t s_last_button_state = 0;
    uint32_t button_state = GPIO_ReadInputDataBit(GPIOA, GPIO_Pin_0);
    
    if (button_state == 0 && s_last_button_state == 1)
    {
        g_pwm_frequency += 100;
        if (g_pwm_frequency > 1000)
        {
            g_pwm_frequency = 100;
        }
    }
    else if (button_state == 1 && s_last_button_state == 0)
    {
        g_pwm_duty_cycle += 10;
        if (g_pwm_duty_cycle > 90)
        {
            g_pwm_duty_cycle = 10;
        }
    }
    
    s_last_button_state = button_state;
}

3. 显示模块的初始化和显示函数：

#include "stm32f10x.h"

void LCD_Init(void)
{
    // TODO: Initialize LCD controller and GPIO pins
}

void LCD_Printf(char *format, ...)
{
    char buffer[64];
    va_list args;
    va_start(args, format);
    vsnprintf(buffer, sizeof(buffer), format, args);
    va_end(args);
    
    // TODO: Display the buffer on the LCD
}

4. 使用DMA传输实现占空比可调：

如果使用DMA传输实现占空比可调，可以将PWM输出的比较寄存器(CCR)的值存储在一个数组中，并在DMA传输完成后将其写入CCR寄存器。对应的代码如下：

#include "stm32f10x.h"

uint32_t g_pwm_ccr_values[101]; // PWM duty cycle values from 0 to 100

void PWM_DMA_Init(void)
{
    DMA_InitTypeDef DMA_InitStructure;
    
    // Enable TIM3 clock
    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM3, ENABLE);
    
    // Enable GPIOB clock
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_GPIOB, ENABLE);
    
    // Configure PB0 as alternate function push-pull
    GPIO_InitTypeDef GPIO_InitStructure;
    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF_PP;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_Init(GPIOB, &GPIO_InitStructure);
    
    // Configure TIM3 as PWM mode 1
    TIM_TimeBaseInitTypeDef TIM_TimeBaseInitStruct;
    TIM_TimeBaseInitStruct.TIM_Period = 999; // PWM frequency = 72MHz / (Period + 1)
    TIM_TimeBaseInitStruct.TIM_Prescaler = 71; // PWM frequency = 72MHz / (Period + 1) / (Prescaler + 1)
    TIM_TimeBaseInitStruct.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseInitStruct.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM3, &TIM_TimeBaseInitStruct);
    
    // Configure DMA channel 3
    RCC_AHBPeriphClockCmd(RCC_AHBPeriph_DMA1, ENABLE);
    DMA_InitStructure.DMA_PeripheralBaseAddr = (uint32_t)&TIM3->CCR1;
    DMA_InitStructure.DMA_MemoryBaseAddr = (uint32_t)&g_pwm_ccr_values;
    DMA_InitStructure.DMA_DIR = DMA_DIR_PeripheralDST;
    DMA_InitStructure.DMA_BufferSize = 101;
    DMA_InitStructure.DMA_PeripheralInc = DMA_PeripheralInc_Disable;
    DMA_InitStructure.DMA_MemoryInc = DMA_MemoryInc_Enable;
    DMA_InitStructure.DMA_PeripheralDataSize = DMA_PeripheralDataSize_Word;
    DMA_InitStructure.DMA_MemoryDataSize = DMA_MemoryDataSize_Word;
    DMA_InitStructure.DMA_Mode = DMA_Mode_Circular;
    DMA_InitStructure.DMA_Priority = DMA_Priority_High;
    DMA_InitStructure.DMA_M2M = DMA_M2M_Disable;
    DMA_Init(DMA1_Channel3, &DMA_InitStructure);
    
    DMA_Cmd(DMA1_Channel3, ENABLE);
    
    // Enable TIM3 DMA requests
    TIM_DMACmd(TIM3, TIM_DMA_CC1, ENABLE);
    
    // Enable TIM3
    TIM_Cmd(TIM3, ENABLE);
}

这样，就可以通过修改g_pwm_ccr_values数组的值来实现PWM输出的占空比可调。

以上是一个简单的实现方法，具体的实现细节和代码实现需要根据具体的硬件平台和开发环境进行调整。