#include "stm32f4xx.h"
#include <string.h>
/* Private variables ---------------------------------------------------------*/
UART_HandleTypeDef huart2;
uint8_t rxBuffer[5] = {0}; // Buffer for receiving data
const char *ping = "PING";
const char *pong = "PONG";
/* Function Prototypes */
void SystemClock_Config(void);
void Error_Handler(void);
void GPIO_Init(void);
void USART2_UART_Init(void);
/**
* @brief The application entry point.
* @retval int
*/
int main(void) {
/* Initialize the HAL Library */
HAL_Init();
/* Configure the system clock */
SystemClock_Config();
/* Initialize GPIO pins and USART2 */
GPIO_Init();
USART2_UART_Init();
while (1) {
// Receive 4 bytes (expecting "PING")
HAL_UART_Receive(&huart2, rxBuffer, 4, HAL_MAX_DELAY);
// Compare received data to "PING"
if (strncmp((char *)rxBuffer, ping, 4) == 0) {
// If "PING" received, send "PONG" back
HAL_UART_Transmit(&huart2, (uint8_t *)pong, strlen(pong), HAL_MAX_DELAY);
}
}
}
/**
* @brief GPIO Initialization Function
* @param None
* @retval None
*/
void GPIO_Init(void) {
GPIO_InitTypeDef GPIO_InitStruct = {0};
/* Enable GPIO clock for PA2 and PA3 (USART2 TX/RX pins) */
__HAL_RCC_GPIOA_CLK_ENABLE();
/* Configure PA2 (USART2 TX) */
GPIO_InitStruct.Pin = GPIO_PIN_2;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP; // Alternate function push-pull
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF7_USART2; // AF7 for USART2
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
/* Configure PA3 (USART2 RX) */
GPIO_InitStruct.Pin = GPIO_PIN_3;
GPIO_InitStruct.Mode = GPIO_MODE_AF_PP; // Alternate function push-pull
GPIO_InitStruct.Pull = GPIO_PULLUP; // Enable pull-up for RX
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_VERY_HIGH;
GPIO_InitStruct.Alternate = GPIO_AF7_USART2; // AF7 for USART2
HAL_GPIO_Init(GPIOA, &GPIO_InitStruct);
}
/**
* @brief USART2 Initialization Function
* @param None
* @retval None
*/
void USART2_UART_Init(void) {
/* Enable USART2 clock */
__HAL_RCC_USART2_CLK_ENABLE();
/* Initialize USART2 */
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;
huart2.Init.OverSampling = UART_OVERSAMPLING_16;
if (HAL_UART_Init(&huart2) != HAL_OK) {
Error_Handler(); // Handle initialization error
}
}
/**
* @brief System Clock Configuration
* @retval None
*/
void SystemClock_Config(void) {
RCC_OscInitTypeDef RCC_OscInitStruct = {0};
RCC_ClkInitTypeDef RCC_ClkInitStruct = {0};
/* Configure the main internal regulator output voltage */
__HAL_RCC_PWR_CLK_ENABLE();
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE2);
/* Initializes the RCC Oscillators according to the specified parameters */
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 = 8;
RCC_OscInitStruct.PLL.PLLN = 100;
RCC_OscInitStruct.PLL.PLLP = RCC_PLLP_DIV2;
RCC_OscInitStruct.PLL.PLLQ = 4;
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_3) != HAL_OK) {
Error_Handler();
}
}
/**
* @brief This function is executed in case of error occurrence.
*/
void Error_Handler(void) {
while (1) {
// Stay in a loop if there is an error
}
}
