STM32使用HAL库驱动4线的电阻屏

其实道理很简单，就是用adc读电压，但细节很多。废话不说，直接上代码，这是给的STemWin驱动，但原理是。如果单独使用，则需要滤波。

第一个细节： 浮空引脚需要内部下拉，否则无法判断是否按压。

第二个细节：ADC的sampling时间不宜过小，否则读数不稳定，无法使用。

#include "GUI.h"  #define XSIZE_PHYS  240 // To be adapted to x-screen size #define YSIZE_PHYS  320 // To be adapted to y-screen size  #define GUI_TOUCH_AD_TOP    3600 #define GUI_TOUCH_AD_BOTTOM 410 #define GUI_TOUCH_AD_LEFT   410 #define GUI_TOUCH_AD_RIGHT  3660  void GUI_TOUCH_X_Init(void) {   GUI_TOUCH_SetOrientation(GUI_SWAP_XY);    GUI_TOUCH_Calibrate(GUI_COORD_X, 0, XSIZE_PHYS, GUI_TOUCH_AD_LEFT, GUI_TOUCH_AD_RIGHT);   GUI_TOUCH_Calibrate(GUI_COORD_Y, 0, YSIZE_PHYS, GUI_TOUCH_AD_TOP, GUI_TOUCH_AD_BOTTOM); }  void GUI_TOUCH_X_ActivateX(void) {   GPIO_InitTypeDef GPIO_InitStruct = {0};    // X- = 0   GPIO_InitStruct.Pin = X_Left_Pin;   GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;   GPIO_InitStruct.Pull = GPIO_NOPULL;   GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;   HAL_GPIO_Init(X_Left_GPIO_Port, &GPIO_InitStruct);   HAL_GPIO_WritePin(X_Left_GPIO_Port, X_Left_Pin, GPIO_PIN_RESET);    // X  = 1   GPIO_InitStruct.Pin = X_RIGHT_Pin;   GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;   GPIO_InitStruct.Pull = GPIO_NOPULL;   GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;   HAL_GPIO_Init(X_RIGHT_GPIO_Port, &GPIO_InitStruct);   HAL_GPIO_WritePin(X_RIGHT_GPIO_Port, X_RIGHT_Pin, GPIO_PIN_SET);    // Enable Y- = NO PULLUP OR DOWN   GPIO_InitStruct.Pin = Y_UP_Pin;   GPIO_InitStruct.Mode = GPIO_MODE_INPUT;   GPIO_InitStruct.Pull = GPIO_PULLDOWN;   HAL_GPIO_Init(Y_UP_GPIO_Port, &GPIO_InitStruct);    // Enable Y  ADC, Channel 3   GPIO_InitStruct.Pin = Y_DOWN_Pin;   GPIO_InitStruct.Mode = GPIO_MODE_ANALOG;   GPIO_InitStruct.Pull = GPIO_NOPULL;   HAL_GPIO_Init(Y_DOWN_GPIO_Port, &GPIO_InitStruct); }  void GUI_TOUCH_X_ActivateY(void) {   GPIO_InitTypeDef GPIO_InitStruct = {0};   // Y- = 0   GPIO_InitStruct.Pin = Y_UP_Pin;   GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;   GPIO_InitStruct.Pull = GPIO_NOPULL;   GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;   HAL_GPIO_Init(Y_UP_GPIO_Port, &GPIO_InitStruct);   HAL_GPIO_WritePin(Y_UP_GPIO_Port, Y_UP_Pin, GPIO_PIN_RESET);    // Y  = 1   GPIO_InitStruct.Pin = Y_DOWN_Pin;   GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;   GPIO_InitStruct.Pull = GPIO_NOPULL;   GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;   HAL_GPIO_Init(Y_DOWN_GPIO_Port, &GPIO_InitStruct);   HAL_GPIO_WritePin(Y_DOWN_GPIO_Port, Y_DOWN_Pin, GPIO_PIN_SET);    // X- NO PULL UP or DOWN   GPIO_InitStruct.Pin = X_Left_Pin;   GPIO_InitStruct.Mode = GPIO_MODE_INPUT;   GPIO_InitStruct.Pull = GPIO_PULLDOWN;   HAL_GPIO_Init(X_Left_GPIO_Port, &GPIO_InitStruct);    // Enable X  ADC, Channel 2   GPIO_InitStruct.Pin = X_RIGHT_Pin;   GPIO_InitStruct.Mode = GPIO_MODE_ANALOG;   GPIO_InitStruct.Pull = GPIO_NOPULL;   HAL_GPIO_Init(X_RIGHT_GPIO_Port, &GPIO_InitStruct); }  int GUI_TOUCH_X_MeasureX(void) {   int result;   ADC_ChannelConfTypeDef sConfig = {0};    /*   * Configure for the selected ADC regular channel its corresponding rank in the sequencer and its sample time.   */   sConfig.Channel = ADC_CHANNEL_2;   sConfig.Rank = 1;   sConfig.SamplingTime = ADC_SAMPLETIME_480CYCLES;   if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)   {     Error_Handler();   }    if (HAL_ADC_Start(&hadc1) != HAL_OK)   {     Error_Handler();   }    if (HAL_ADC_PollForConversion(&hadc1, 10) != HAL_OK)   {     Error_Handler();   }   result = HAL_ADC_GetValue(&hadc1);    if (HAL_ADC_Stop(&hadc1) != HAL_OK)   {     Error_Handler();   }    return result; }  int GUI_TOUCH_X_MeasureY(void) {   int result;   ADC_ChannelConfTypeDef sConfig = {0};    /*   * Configure for the selected ADC regular channel its corresponding rank in the sequencer and its sample time.   */   sConfig.Channel = ADC_CHANNEL_3;   sConfig.Rank = 1;   sConfig.SamplingTime = ADC_SAMPLETIME_480CYCLES;   if (HAL_ADC_ConfigChannel(&hadc1, &sConfig) != HAL_OK)   {     Error_Handler();   }    if (HAL_ADC_Start(&hadc1) != HAL_OK)   {     Error_Handler();   }    if (HAL_ADC_PollForConversion(&hadc1, 10) != HAL_OK)   {     Error_Handler();   }   result = HAL_ADC_GetValue(&hadc1);    if (HAL_ADC_Stop(&hadc1) != HAL_OK)   {     Error_Handler();   }    return result; }