蓝桥杯扩展板模块（基于新版STM32G431）——ADC按键
一、ADC按键原理
如上原理图所示，也是经过学习这个扩展板我才知道原来还有这么巧妙的方法。原理其实很简单，就是一个电阻分压而已，不同的按键按下，电阻就变了，所以检测得到的电压也就不一样，通过检测得到的电压来判断到底是哪一个按键被按下。
这种电路的优点就是很节省IO口，只需要一个IO口就可以检测这么多按键。但是缺点就是受硬件影响比较大，不同的板子，电阻也略有不同，检测得到的电压也有不同，还有一个问题就是不支持多个按键同时触发，如果多个按键同时触发就会产生混乱。
经过我的测试不同的按键按下ADC的值如下，（仅供参考，因为不同的板子会有一些不一样）：
| 按键 | Value |
|---|---|
| 无 | 4039 |
| KEY1 | 5 |
| KEY2 | 541 |
| KEY3 | 1145 |
| KEY4 | 1740 |
| KEY5 | 2350 |
| KEY6 | 2855 |
| KEY7 | 3471 |
| KEY8 | 3936 |
在检测哪一个按键被按下的时候，就通过判断adc的值的区间就行了。
二、CubeMx的配置
把ADC DMA中断关闭了，否则会一直进入中断打断cpu的执行。
三、主要代码
完整main.c代码：
在程序中，定时器4是1ms产生一次中断，每10ms扫描一次按键的状态（消抖）。
关于ADC 按键的部分，首先要开始ADC DMAHAL_ADC_Start_DMA(&hadc2,(uint32_t*)&adc_key_value,1);，这样ADC的实时的值将会被放在adc_key_value里面，在ADC按键扫描程序adc_key_scan()里面我们使用的是三行按键扫描的方法，这个不懂的在我之前的博客里面有。
/* USER CODE BEGIN Header */
/**
******************************************************************************
* @file : main.c
* @brief : Main program body
******************************************************************************
* @attention
*
* <h2><center>© Copyright (c) 2021 STMicroelectronics.
* All rights reserved.</center></h2>
*
* This software component is licensed by ST under BSD 3-Clause license,
* the "License"; You may not use this file except in compliance with the
* License. You may obtain a copy of the License at:
* opensource.org/licenses/BSD-3-Clause
*
******************************************************************************
*/
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.h"
#include "adc.h"
#include "dma.h"
#include "tim.h"
#include "gpio.h"
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
/* USER CODE END Includes */
/* Private typedef -----------------------------------------------------------*/
/* USER CODE BEGIN PTD */
/* USER CODE END PTD */
/* Private define ------------------------------------------------------------*/
/* USER CODE BEGIN PD */
/* USER CODE END PD */
/* Private macro -------------------------------------------------------------*/
/* USER CODE BEGIN PM */
/* USER CODE END PM */
/* Private variables ---------------------------------------------------------*/
/* USER CODE BEGIN PV */
uint16_t led_tick = 0;
_Bool led_flag = 0;
uint8_t key_tick = 0;
uint16_t adc_key_value;
uint8_t adc_key_tick = 0;
_Bool adc_key_flag;
uint8_t lcd_str[20];
/* USER CODE END PV */
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
/* USER CODE BEGIN PFP */
void led_proc(void);
void key_scan(void);
void adc_key_scan(void);
/* USER CODE END PFP */
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
/* USER CODE END 0 */
/**
* @brief The application entry point.
* @retval int
*/
int main(void)
{
/* USER CODE BEGIN 1 */
/* USER CODE END 1 */
/* MCU Configuration--------------------------------------------------------*/
/* Reset of all peripherals, Initializes the Flash interface and the Systick. */
HAL_Init();
/* USER CODE BEGIN Init */
/* USER CODE END Init */
/* Configure the system clock */
SystemClock_Config();
/* USER CODE BEGIN SysInit */
/* USER CODE END SysInit */
/* Initialize all configured peripherals */
MX_GPIO_Init();
MX_DMA_Init();
MX_TIM4_Init();
MX_ADC2_Init();
/* USER CODE BEGIN 2 */
LCD_Init();
led_init();
HAL_TIM_Base_Start_IT(&htim4);
HAL_ADCEx_Calibration_Start(&hadc2,ADC_SINGLE_ENDED);
HAL_ADC_Start_DMA(&hadc2,(uint32_t*)&adc_key_value,1);
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
LCD_Clear(Blue);
LCD_SetBackColor(Blue);
LCD_SetTextColor(White);
LCD_DisplayStringLine(Line0, (uint8_t *)" ");
LCD_DisplayStringLine(Line1, (uint8_t *)" ");
LCD_DisplayStringLine(Line2, (uint8_t *)" LCD Test ");
LCD_DisplayStringLine(Line3, (uint8_t *)" ");
LCD_DisplayStringLine(Line4, (uint8_t *)" ");
LCD_SetBackColor(White);
LCD_SetTextColor(Blue);
LCD_DisplayStringLine(Line5, (uint8_t *)" ");
LCD_DisplayStringLine(Line6, (uint8_t *)" HAL LIB ");
LCD_DisplayStringLine(Line7, (uint8_t *)" ");
LCD_DisplayStringLine(Line8, (uint8_t *)" ");
LCD_DisplayStringLine(Line9, (uint8_t *)" ");
while (1)
{
/* USER CODE END WHILE */
/* USER CODE BEGIN 3 */
led_proc();
}
/* USER CODE END 3 */
}
/**
* @brief System Clock Configuration
* @retval None
*/
void SystemClock_Config(void)
{
RCC_OscInitTypeDef RCC_OscInitStruct = {
0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {
0};
RCC_PeriphCLKInitTypeDef PeriphClkInit = {
0};
/** Configure the main internal regulator output voltage
*/
HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE1);
/** Initializes the CPU, AHB and APB busses clocks
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_HSE;
RCC_OscInitStruct.HSEState = RCC_HSE_ON;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSE;
RCC_OscInitStruct.PLL.PLLM = RCC_PLLM_DIV3;
RCC_OscInitStruct.PLL.PLLN = 20;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
RCC_OscInitStruct.PLL.PLLQ = RCC_PLLQ_DIV2;
RCC_OscInitStruct.PLL.PLLR = RCC_PLLR_DIV2;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
/** Initializes the CPU, AHB and APB busses 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_DIV1;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_3) != HAL_OK)
{
Error_Handler();
}
/** Initializes the peripherals clocks
*/
PeriphClkInit.PeriphClockSelection = RCC_PERIPHCLK_ADC12;
PeriphClkInit.Adc12ClockSelection = RCC_ADC12CLKSOURCE_SYSCLK;
if (HAL_RCCEx_PeriphCLKConfig(&PeriphClkInit) != HAL_OK)
{
Error_Handler();
}
}
/* USER CODE BEGIN 4 */
void key_scan(void)
{
key_refresh();
if(key_falling == B1)
{
led_toggle(LD5);
}
else if(key_falling == B2)
{
led_toggle(LD6);
}
else if(key_falling == B3)
{
led_toggle(LD7);
}
else if(key_falling == B4)
{
led_toggle(LD8);
}
}
void led_proc(void)
{
if(led_flag)
{
led_flag = 0;
// led_toggle(LD1);
}
}
void adc_key_scan(void)
{
static uint8_t adc_key_falling = 0;
static uint8_t adc_key_state = 0;
uint8_t adc_key_temp = 0x00;
if(adc_key_value < 300)
adc_key_temp |= 0x01;
else if(adc_key_value < 800)
adc_key_temp |= 0x02;
else if(adc_key_value < 1500)
adc_key_temp |= 0x04;
else if(adc_key_value < 2000)
adc_key_temp |= 0x08;
else if(adc_key_value < 2500)
adc_key_temp |= 0x10;
else if(adc_key_value < 3200)
adc_key_temp |= 0x20;
else if(adc_key_value < 3500)
adc_key_temp |= 0x40;
else if(adc_key_value < 4000)
adc_key_temp |= 0x80;
adc_key_falling = adc_key_temp & (adc_key_state ^ adc_key_temp);
adc_key_state = adc_key_temp;
memset(lcd_str,0,sizeof(lcd_str));
sprintf((char*)lcd_str,"Value:%d ",adc_key_value);
LCD_DisplayStringLine(Line8, lcd_str);
if(adc_key_falling == 0x01)
{
led_toggle(LD1);
}
else if(adc_key_falling == 0x02)
{
led_toggle(LD2);
}
else if(adc_key_falling == 0x04)
{
led_toggle(LD3);
}
else if(adc_key_falling == 0x08)
{
led_toggle(LD4);
}
else if(adc_key_falling == 0x10)
{
led_toggle(LD5);
}
else if(adc_key_falling == 0x20)
{
led_toggle(LD6);
}
else if(adc_key_falling == 0x40)
{
led_toggle(LD7);
}
else if(adc_key_falling == 0x80)
{
led_toggle(LD8);
}
}
void HAL_TIM_PeriodElapsedCallback(TIM_HandleTypeDef *htim)
{
if(htim->Instance == TIM4)
{
if(++led_tick == 1000)
{
led_tick = 0;
led_flag = 1;
}
if(++key_tick == 10)
{
key_tick = 0;
key_scan();
}
if(++adc_key_tick == 10)
{
adc_key_tick = 0;
adc_key_scan();
}
}
}
/* USER CODE END 4 */
/**
* @brief This function is executed in case of error occurrence.
* @retval None
*/
void Error_Handler(void)
{
/* USER CODE BEGIN Error_Handler_Debug */
/* User can add his own implementation to report the HAL error return state */
/* USER CODE END Error_Handler_Debug */
}
#ifdef USE_FULL_ASSERT
/**
* @brief Reports the name of the source file and the source line number
* where the assert_param error has occurred.
* @param file: pointer to the source file name
* @param line: assert_param error line source number
* @retval None
*/
void assert_failed(uint8_t *file, uint32_t line)
{
/* USER CODE BEGIN 6 */
/* User can add his own implementation to report the file name and line number,
tex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
/* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */
/************************ (C) COPYRIGHT STMicroelectronics *****END OF FILE****/