以C语言为基础，编写利用XPT2046作为模数转换器的程序；AD转换部分在定时器中断中实现，1.先编写XPT2046控制和处理程序； 2.再编写八段数码管显示程序； 3.再编写主程序；

好的，下面是一个基于C语言的XPT2046和八段数码管的程序示例：

1. XPT2046控制和处理程序

#include <stm32f4xx.h>

void SPI1_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;
    SPI_InitTypeDef  SPI_InitStructure;

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOA, ENABLE);
    RCC_APB2PeriphClockCmd(RCC_APB2Periph_SPI1, ENABLE);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_5 | GPIO_Pin_6 | GPIO_Pin_7;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_AF;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_Init(GPIOA, &GPIO_InitStructure);

    GPIO_PinAFConfig(GPIOA, GPIO_PinSource5, GPIO_AF_SPI1);
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource6, GPIO_AF_SPI1);
    GPIO_PinAFConfig(GPIOA, GPIO_PinSource7, GPIO_AF_SPI1);

    SPI_InitStructure.SPI_Direction = SPI_Direction_2Lines_FullDuplex;
    SPI_InitStructure.SPI_Mode = SPI_Mode_Master;
    SPI_InitStructure.SPI_DataSize = SPI_DataSize_8b;
    SPI_InitStructure.SPI_CPOL = SPI_CPOL_Low;
    SPI_InitStructure.SPI_CPHA = SPI_CPHA_1Edge;
    SPI_InitStructure.SPI_NSS = SPI_NSS_Soft;
    SPI_InitStructure.SPI_BaudRatePrescaler = SPI_BaudRatePrescaler_4;
    SPI_InitStructure.SPI_FirstBit = SPI_FirstBit_MSB;
    SPI_InitStructure.SPI_CRCPolynomial = 7;
    SPI_Init(SPI1, &SPI_InitStructure);

    SPI_Cmd(SPI1, ENABLE);
}

uint8_t SPI1_WriteByte(uint8_t byte)
{
    while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_TXE) == RESET);
    SPI_I2S_SendData(SPI1, byte);
    while (SPI_I2S_GetFlagStatus(SPI1, SPI_I2S_FLAG_RXNE) == RESET);
    return SPI_I2S_ReceiveData(SPI1);
}

void XPT2046_Init(void)
{
    // 初始化SPI接口
    SPI1_Init();

    // 发送复位指令
    SPI1_WriteByte(0x80);
    SPI1_WriteByte(0x00);
    SPI1_WriteByte(0x00);
}

uint16_t XPT2046_ReadADC(uint8_t channel)
{
    uint16_t result = 0;

    // 发送读取指令
    SPI1_WriteByte(0x80 | (channel << 4));
    SPI1_WriteByte(0x00);
    result = SPI1_WriteByte(0x00);
    result <<= 8;
    result |= SPI1_WriteByte(0x00);
    result >>= 3;

    return result;
}

2. 八段数码管显示程序

#include <stm32f4xx.h>

void GPIO_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStructure;

    RCC_AHB1PeriphClockCmd(RCC_AHB1Periph_GPIOB, ENABLE);

    GPIO_InitStructure.GPIO_Pin = GPIO_Pin_0 | GPIO_Pin_1 | GPIO_Pin_2 | GPIO_Pin_3 | GPIO_Pin_4 | GPIO_Pin_5 | GPIO_Pin_6 | GPIO_Pin_7;
    GPIO_InitStructure.GPIO_Mode = GPIO_Mode_OUT;
    GPIO_InitStructure.GPIO_Speed = GPIO_Speed_50MHz;
    GPIO_InitStructure.GPIO_OType = GPIO_OType_PP;
    GPIO_InitStructure.GPIO_PuPd = GPIO_PuPd_UP;
    GPIO_Init(GPIOB, &GPIO_InitStructure);
}

void DisplayDigit(uint8_t digit)
{
    const uint8_t digit_codes[] = {
        0x3F, 0x06, 0x5B, 0x4F, 0x66, 
        0x6D, 0x7D, 0x07, 0x7F, 0x6F
    };

    uint8_t code = digit_codes[digit];
    GPIOB->ODR = code;
}

3. 主程序

#include <stm32f4xx.h>

void TIM2_Init(void)
{
    TIM_TimeBaseInitTypeDef TIM_TimeBaseStructure;
    NVIC_InitTypeDef NVIC_InitStructure;

    RCC_APB1PeriphClockCmd(RCC_APB1Periph_TIM2, ENABLE);

    TIM_TimeBaseStructure.TIM_Period = 65535; // 定时器周期为2^16-1
    TIM_TimeBaseStructure.TIM_Prescaler = 84 - 1; // 定时器时钟频率为84MHz
    TIM_TimeBaseStructure.TIM_ClockDivision = TIM_CKD_DIV1;
    TIM_TimeBaseStructure.TIM_CounterMode = TIM_CounterMode_Up;
    TIM_TimeBaseInit(TIM2, &TIM_TimeBaseStructure);

    TIM_ITConfig(TIM2, TIM_IT_Update, ENABLE);
    TIM_Cmd(TIM2, ENABLE);

    NVIC_InitStructure.NVIC_IRQChannel = TIM2_IRQn;
    NVIC_InitStructure.NVIC_IRQChannelPreemptionPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelSubPriority = 0;
    NVIC_InitStructure.NVIC_IRQChannelCmd = ENABLE;
    NVIC_Init(&NVIC_InitStructure);
}

void TIM2_IRQHandler(void)
{
    uint16_t adc_value = XPT2046_ReadADC(0);
    uint8_t digit = (adc_value * 10) / 4096;
    DisplayDigit(digit);

    TIM_ClearITPendingBit(TIM2, TIM_IT_Update);
}

int main(void)
{
    XPT2046_Init();
    GPIO_Init();
    TIM2_Init();

    while (1) {}
}

注意：以上代码仅为示例，具体的实现方式需要根据您的硬件和编程环境而不同。同时，如果您在实现过程中遇到了具体的问题，可以在相应的技术社区或论坛上寻求帮助。