在这句代码中Uart1_Buffer[i++] = (USART_ReceiveData(USART1))&0xff; 假如i的初始值是0，那第一次运行的时候，i是多少

根据给出的代码片段：

Uart1_Buffer[i++] = (USART_ReceiveData(USART1))&0xff;

假设i的初始值是0，那么第一次运行时，i的值将是1。

在这行代码中，先执行了`USART_ReceiveData(USART1)`函数来获取USART1接收寄存器中的数据，然后使用位运算符`&`和掩码0xff将数据截取为8位，最后将截取后的数据存储到Uart1_Buffer数组中的索引位置i。然后，通过`i++`操作符来将i的值自增1。

因此，在第一次运行时，i的初始值为0，经过一次运行后，i的值将变为1。

相关问题

stm32f103c8t6串口2发送AT+LOCATION=1指令给EC01g,并解析GPS,显示到屏幕,stm32库函数版本的代码

下面是基于STM32 HAL库的串口2发送AT指令并解析GPS数据的代码，供参考：

#include "stm32f1xx_hal.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define GPS_BUFFER_SIZE 256

UART_HandleTypeDef huart2;

char gps_buffer[GPS_BUFFER_SIZE];
int gps_buffer_index = 0;

void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_USART2_UART_Init(void);

void HAL_UART_RxCpltCallback(UART_HandleTypeDef *huart)
{
    if (huart->Instance == USART2)
    {
        if (gps_buffer_index < GPS_BUFFER_SIZE - 1)
        {
            gps_buffer[gps_buffer_index++] = huart->Instance->DR & 0xFF;
        }
    }
}

void clear_gps_buffer()
{
    memset(gps_buffer, 0, GPS_BUFFER_SIZE);
    gps_buffer_index = 0;
}

void send_at_command(char* command)
{
    HAL_UART_Transmit(&huart2, (uint8_t*)command, strlen(command), HAL_MAX_DELAY);
}

void parse_gps_data(char* gps_data)
{
    char* token = strtok(gps_data, ",");
    int count = 0;
    while (token != NULL)
    {
        if (count == 3) // latitude
        {
            float latitude = atof(token);
            printf("Latitude: %f\n", latitude);
        }
        else if (count == 4) // north or south
        {
            if (strcmp(token, "S") == 0)
            {
                printf("Direction: South\n");
            }
            else
            {
                printf("Direction: North\n");
            }
        }
        else if (count == 5) // longitude
        {
            float longitude = atof(token);
            printf("Longitude: %f\n", longitude);
        }
        else if (count == 6) // east or west
        {
            if (strcmp(token, "W") == 0)
            {
                printf("Direction: West\n");
            }
            else
            {
                printf("Direction: East\n");
            }
        }
        token = strtok(NULL, ",");
        count++;
    }
}

int main(void)
{
    HAL_Init();
    SystemClock_Config();
    MX_GPIO_Init();
    MX_USART2_UART_Init();

    while (1)
    {
        send_at_command("AT+LOCATION=1\r\n");
        HAL_Delay(1000);
        char* search_str = "+LOCATION:";
        char* ptr = strstr(gps_buffer, search_str);
        if (ptr != NULL)
        {
            ptr += strlen(search_str);
            parse_gps_data(ptr);
        }
        clear_gps_buffer();
        HAL_Delay(5000);
    }
}

void SystemClock_Config(void)
{
    RCC_OscInitTypeDef RCC_OscInitStruct = {0};
    RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};

    /** Initializes the RCC Oscillators according to the specified parameters
    * in the RCC_OscInitTypeDef structure.
    */
    RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
    RCC_OscInitStruct.HSEState = RCC_HSE_ON;
    RCC_OscInitStruct.HSEPredivValue = RCC_HSE_PREDIV_DIV1;
    RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
    RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
    RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL9;
    if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
    {
        Error_Handler();
    }
    /** Initializes the CPU, AHB and APB buses clocks
    */
    RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK | RCC_CLOCKTYPE_SYSCLK
    | RCC_CLOCKTYPE_PCLK1 | RCC_CLOCKTYPE_PCLK2;
    RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_PLLCLK;
    RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
    RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV2;
    RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;

    if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_2) != HAL_OK)
    {
        Error_Handler();
    }
}

static void MX_USART2_UART_Init(void)
{
    huart2.Instance = USART2;
    huart2.Init.BaudRate = 115200;
    huart2.Init.WordLength = UART_WORDLENGTH_8B;
    huart2.Init.StopBits = UART_STOPBITS_1;
    huart2.Init.Parity = UART_PARITY_NONE;
    huart2.Init.Mode = UART_MODE_TX_RX;
    huart2.Init.HwFlowCtl = UART_HWCONTROL_NONE;
    huart2.Init.OverSampling = UART_OVERSAMPLING_16;
    if (HAL_UART_Init(&huart2) != HAL_OK)
    {
        Error_Handler();
    }
    HAL_UART_Receive_IT(&huart2, (uint8_t*)gps_buffer, 1);
}

static void MX_GPIO_Init(void)
{
    GPIO_InitTypeDef GPIO_InitStruct = {0};

    /* GPIO Ports Clock Enable */
    __HAL_RCC_GPIOC_CLK_ENABLE();
    __HAL_RCC_GPIOD_CLK_ENABLE();
    __HAL_RCC_GPIOA_CLK_ENABLE();

    /*Configure GPIO pin Output Level */
    HAL_GPIO_WritePin(GPIOC, GPIO_PIN_13, GPIO_PIN_RESET);

    /*Configure GPIO pin : PC13 */
    GPIO_InitStruct.Pin = GPIO_PIN_13;
    GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
    HAL_GPIO_Init(GPIOC, &GPIO_InitStruct);
}

需要注意的是，这只是一个简单的示例代码，无法保证完全正确和可靠，需要根据具体需求进行调整和修改。同时，还需要根据具体的硬件连接情况进行相应的配置。

使用stm32读取两个传感器的数据。传感器1：通过UART1发送FF 01 03 02 00 00 00 00 FB为关闭主动上报,发送：FF 01 03 03 02 00 00 00 F8，向传感器问询，传感器返回:XXX+%(ASCII码，数值+单位%),把返回的数值以float类型，保留四位小数保存。传感器2：通过UART2发送：11 01 01 ED读取O2 测量结果，返回结果为：16 09 01 DF1 DF2 DF3 DF4 DF5 DF6 DF7 DF8 [CS]，数据处理方法为：O2 浓度值= （DF1*256 + DF2）/10 （Vol %），O2 流量值= （DF3*256 + DF4）/10 （L/min），O2 温度值= （DF5*256 + DF6）/10 （℃）。帮我写—段使用STM32F429，标准库读取这个传感器数值的代码

以下是使用STM32F429标准库读取传感器1和传感器2数值的代码：

#include "stm32f4xx.h"
#include <stdio.h>
#include <string.h>

#define UART1_TX_PIN GPIO_Pin_9
#define UART1_RX_PIN GPIO_Pin_10
#define UART2_TX_PIN GPIO_Pin_5
#define UART2_RX_PIN GPIO_Pin_6

UART_HandleTypeDef UART1_Handle, UART2_Handle;

void MX_GPIO_Init(void);
void MX_USART1_UART_Init(void);
void MX_USART2_UART_Init(void);

void read_sensor1(void);
void read_sensor2(void);

int main(void) {
    HAL_Init();
    MX_GPIO_Init();
    MX_USART1_UART_Init();
    MX_USART2_UART_Init();
    
    while (1) {
        read_sensor1();
        read_sensor2();
    }
}

void read_sensor1(void) {
    uint8_t txData[] = {0xFF, 0x01, 0x03, 0x03, 0x02, 0x00, 0x00, 0x00, 0xF8};
    uint8_t rxData[100];
    uint32_t timeout = 1000;
    float value;
    
    // Send command to sensor 1
    HAL_UART_Transmit(&UART1_Handle, txData, sizeof(txData), timeout);
    
    // Wait for response from sensor 1
    HAL_UART_Receive(&UART1_Handle, rxData, sizeof(rxData), timeout);
    
    // Extract value from response
    char* start = strchr((char*)rxData, '%') + 1;
    char* end = strchr(start, '%');
    char valueStr[10];
    strncpy(valueStr, start, end - start);
    value = atof(valueStr);
    
    // Print value
    printf("Sensor 1 value: %.4f\n", value);
}

void read_sensor2(void) {
    uint8_t txData[] = {0x11, 0x01, 0x01, 0xED};
    uint8_t rxData[100];
    uint32_t timeout = 1000;
    float o2Concentration, o2FlowRate, o2Temperature;
    
    // Send command to sensor 2
    HAL_UART_Transmit(&UART2_Handle, txData, sizeof(txData), timeout);
    
    // Wait for response from sensor 2
    HAL_UART_Receive(&UART2_Handle, rxData, sizeof(rxData), timeout);
    
    // Extract data from response
    uint16_t df1 = (rxData[3] << 8) | rxData[4];
    uint16_t df2 = (rxData[5] << 8) | rxData[6];
    uint16_t df3 = (rxData[7] << 8) | rxData[8];
    uint16_t df4 = (rxData[9] << 8) | rxData[10];
    uint16_t df5 = (rxData[11] << 8) | rxData[12];
    uint16_t df6 = (rxData[13] << 8) | rxData[14];
    
    o2Concentration = ((float)(df1 * 256 + df2)) / 10.0;
    o2FlowRate = ((float)(df3 * 256 + df4)) / 10.0;
    o2Temperature = ((float)(df5 * 256 + df6)) / 10.0;
    
    // Print data
    printf("Sensor 2 O2 concentration: %.4f Vol %%\n", o2Concentration);
    printf("Sensor 2 O2 flow rate: %.4f L/min\n", o2FlowRate);
    printf("Sensor 2 O2 temperature: %.4f deg C\n", o2Temperature);
}

void MX_GPIO_Init(void) {
    GPIO_InitTypeDef GPIO_InitStruct;
    
    __GPIOA_CLK_ENABLE();
    __GPIOB_CLK_ENABLE();
    __GPIOC_CLK_ENABLE();
    
    // UART1 GPIO configuration
    GPIO_InitStruct.Pin = UART1_TX_PIN | UART1_RX_PIN;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
    GPIO_InitStruct.Alternate = GPIO_AF7_USART1;
    HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
    
    // UART2 GPIO configuration
    GPIO_InitStruct.Pin = UART2_TX_PIN | UART2_RX_PIN;
    GPIO_InitStruct.Mode = GPIO_MODE_AF_PP;
    GPIO_InitStruct.Pull = GPIO_NOPULL;
    GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_HIGH;
    GPIO_InitStruct.Alternate = GPIO_AF7_USART2;
    HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
}

void MX_USART1_UART_Init(void) {
    UART1_Handle.Instance = USART1;
    UART1_Handle.Init.BaudRate = 9600;
    UART1_Handle.Init.WordLength = UART_WORDLENGTH_8B;
    UART1_Handle.Init.StopBits = UART_STOPBITS_1;
    UART1_Handle.Init.Parity = UART_PARITY_NONE;
    UART1_Handle.Init.Mode = UART_MODE_TX_RX;
    UART1_Handle.Init.HwFlowCtl = UART_HWCONTROL_NONE;
    UART1_Handle.Init.OverSampling = UART_OVERSAMPLING_16;
    HAL_UART_Init(&UART1_Handle);
}

void MX_USART2_UART_Init(void) {
    UART2_Handle.Instance = USART2;
    UART2_Handle.Init.BaudRate = 9600;
    UART2_Handle.Init.WordLength = UART_WORDLENGTH_8B;
    UART2_Handle.Init.StopBits = UART_STOPBITS_1;
    UART2_Handle.Init.Parity = UART_PARITY_NONE;
    UART2_Handle.Init.Mode = UART_MODE_TX_RX;
    UART2_Handle.Init.HwFlowCtl = UART_HWCONTROL_NONE;
    UART2_Handle.Init.OverSampling = UART_OVERSAMPLING_16;
    HAL_UART_Init(&UART2_Handle);
}

在主函数中，我们调用 `read_sensor1()` 和 `read_sensor2()` 函数分别读取传感器1和传感器2的数据。这两个函数分别使用 `HAL_UART_Transmit()` 和 `HAL_UART_Receive()` 函数来发送和接收数据。接收到数据后，我们需要对数据进行处理，提取出需要的数值并转换为 `float` 类型。最后我们使用 `printf()` 函数将数值打印出来。

需要注意的是，在初始化函数中我们需要配置每个UART的GPIO引脚。在本例中，我们使用了USART1和USART2，并且将它们的TX引脚连接到PB9和PA5，RX引脚连接到PB10和PA6。