如图所示，说这个函数第一次定义，我该怎么修改？

楼主截的图看不清，好像少了花括号。

菜单栏打开Project->Option for Target‘STM32L476G-Discovery’->User
参考人家是怎么弄的，看看自己有没有漏掉什么代码规则，初始化代码设置有没有漏写
#include "stm32l4xx.h"
#include "stm32l476g_discovery.h"
UART_HandleTypeDef huart2;
GPIO_InitTypeDef GPIO_InitStruct;
void configure_system_clock(void);

int main(void)
{
    HAL_Init(); // HAL Init

    configure_system_clock(); // Configure Clock
    __GPIOD_CLK_ENABLE(); // Enable GPIOD clock
    __USART2_CLK_ENABLE(); // Enable USART2 Clock
    huart2.Instance = USART2;
    huart2.Init.BaudRate = 9600;
    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;
    HAL_UART_Init(&huart2);

后面就不粘贴了，可以参考下

有初始化代码，括号也没少
#include "stm32l4xx.h"
#include "stm32l476g_discovery.h"

ADC_HandleTypeDef  hadc1;
DMA_HandleTypeDef  hdma_adc1;

void ADC1_conf(void)
{
  ADC_ChannelConfTypeDef sConfig;
  HAL_ADC_Init(&hadc1);
  /**Configure the global features of the ADC (Clock, Resolution, Data,Alignment and number of conversion) */
  hadc1.Instance = ADC1;
  hadc1.Init.ClockPrescaler = ADC_CLOCK_SYNC_PCLK_DIV2;
  hadc1.Init.Resolution = ADC_RESOLUTION_12B;
  hadc1.Init.ScanConvMode = ENABLE;    //upward
  hadc1.Init.ContinuousConvMode = ENABLE;
  hadc1.Init.DiscontinuousConvMode = DISABLE;
  hadc1.Init.ExternalTrigConvEdge = ADC_SOFTWARE_START;    //software trigger
  hadc1.Init.ExternalTrigConvEdge  = ADC_EXTERNALTRIGCONVEDGE_RISING;     //rising edge
  hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;     //< Data right alignment
  hadc1.Init.NbrOfConversion = 2;                /* This parameter must be a number between Min_Data = 1 and Max_Data = 16.
                                                Note: This parameter must be modified when no conversion is on going on regular group (ADC disabled,
                                                or ADC enabled without continuous mode or external trigger that could launch a conversion). */
  hadc1.Init.DMAContinuousRequests = ENABLE;
  hadc1.Init.EOCSelection = ADC_EOC_SINGLE_CONV;


  /**Configure for the selected ADC regular channel its corresponding rank in the sequencer and its sample time. */
  sConfig.Channel = ADC_CHANNEL_5;
  sConfig.Rank = 1;
  sConfig.SamplingTime = ADC_SAMPLETIME_12CYCLES_5;  //  Sampling time 12.5 ADC clock cycles at ADC resolution 12 bits.
  HAL_ADC_ConfigChannel(&hadc1, &sConfig);

  /**Configure for the selected ADC regular channel its corresponding rank in the sequencer and its sample time. */
  sConfig.Channel = ADC_CHANNEL_3;
  sConfig.Rank = 2;
  HAL_ADC_ConfigChannel(&hadc1, &sConfig);
}

在ADC.H中声明该函数
void ADC1_conf(void)；

看看头文件里函数的声明有没有丢分号什么的

见5楼，

在ADC.H中声明该函数
void ADC1_conf(void)；

在.c中定义函数，在.h中声明函数。
在要调用ADC1_conf()函数的.c文件中，把ADC.H包含进来，#include ADC.H


套路就是这么个套路，c语言功底，好好学习一下

按2、5、7楼所说的做了，然而并没有解决这个BUG

#include "stm32l4xx.h"
//#include "stm32l476g_discovery.h"
#include "adc.h"
#include "stm32l4xx_hal_adc.h"
ADC_HandleTypeDef  hadc1;
DMA_HandleTypeDef  hdma_adc1;

ADC_ChannelConfTypeDef sConfig;

void ADC1_conf(void)
{
        HAL_Init(); // HAL Init
  /**Configure the global features of the ADC (Clock, Resolution, Data,Alignment and number of conversion) */
  hadc1.Instance = ADC1;
  hadc1.Init.ClockPrescaler = ADC_CLOCK_SYNC_PCLK_DIV2;
  hadc1.Init.Resolution = ADC_RESOLUTION_12B;
  hadc1.Init.ScanConvMode = ENABLE;    //upward
  hadc1.Init.ContinuousConvMode = ENABLE;
  hadc1.Init.DiscontinuousConvMode = DISABLE;
  hadc1.Init.ExternalTrigConvEdge = ADC_SOFTWARE_START;    //software trigger
  hadc1.Init.ExternalTrigConvEdge  = ADC_EXTERNALTRIGCONVEDGE_RISING;     //rising edge
  hadc1.Init.DataAlign = ADC_DATAALIGN_RIGHT;     //< Data right alignment
  hadc1.Init.NbrOfConversion = 2;                /* This parameter must be a number between Min_Data = 1 and Max_Data = 16.
                                                Note: This parameter must be modified when no conversion is on going on regular group (ADC disabled,
                                                or ADC enabled without continuous mode or external trigger that could launch a conversion). */
  hadc1.Init.DMAContinuousRequests = ENABLE;
  hadc1.Init.EOCSelection = ADC_EOC_SINGLE_CONV;


  /**Configure for the selected ADC regular channel its corresponding rank in the sequencer and its sample time. */
  sConfig.Channel = ADC_CHANNEL_5;
  sConfig.Rank = 1;
  sConfig.SamplingTime = ADC_SAMPLETIME_12CYCLES_5;  //  Sampling time 12.5 ADC clock cycles at ADC resolution 12 bits.
  HAL_ADC_ConfigChannel(&hadc1, &sConfig);

  /**Configure for the selected ADC regular channel its corresponding rank in the sequencer and its sample time. */
  sConfig.Channel = ADC_CHANNEL_3;
  sConfig.Rank = 2;
  HAL_ADC_ConfigChannel(&hadc1, &sConfig);

}

上半部分是adc.c
这一部分是adc.h

#define MX_ADC1_Init
/* Definition for USARTx Pins */

#include "stm32l4xx.h"
#include "stm32l476g_discovery.h"

void ADC1_conf(void);
//void HAL_ADC_Init(ADC_HandleTypeDef* hadc);
void HAL_ADC_MspInit(ADC_HandleTypeDef* hadc);
void HAL_ADC_MspDeInit(ADC_HandleTypeDef* hadc);

#define USARTx_TX_PIN                    GPIO_PIN_6
#define USARTx_TX_GPIO_PORT              GPIOB
#define USARTx_TX_AF                     GPIO_AF7_USART1
#define USARTx_RX_PIN                    GPIO_PIN_7
#define USARTx_RX_GPIO_PORT              GPIOB
#define USARTx_RX_AF                     GPIO_AF7_USART1

"first defined here"是不是意味着有其他地方defined呢？有编译的报错截图吗？