Assistance Needed with UART Communication Between Nucleo-F103RB and RAK3272S Breakout Board

I hope this message finds you well.

I am currently working on a project involving UART communication between an STM32 Nucleo-F103RB board and a RAK3272S Breakout Board. My goal is to send AT commands from the Nucleo board and receive the response from the RAK3272S Breakout Board, displaying the result on the serial monitor.

I have written the following code, but I am facing an issue where the expected response from the RAK3272S Breakout Board is not being displayed. Below is the code I am using:

#include "main.h"
#include "string.h"
#include "stdio.h"

UART_HandleTypeDef huart2;

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

int main(void)
{

  HAL_Init();

  SystemClock_Config();

  MX_GPIO_Init();
  MX_USART2_UART_Init();

  uint8_t at_command = "Hello\n";
  uint8_t rx_buffer[256];

  HAL_StatusTypeDef result;

  while (1)
  {
   HAL_UART_Transmit(&huart2, at_command, sizeof(at_command), 1000);
   memset(rx_buffer, 0, sizeof(rx_buffer));

   result = HAL_UART_Receive(&huart2, rx_buffer, sizeof(rx_buffer), HAL_MAX_DELAY);

   if (result == HAL_OK)
   {
      HAL_UART_Transmit(&huart2, rx_buffer, sizeof(rx_buffer), HAL_MAX_DELAY); // send received data
   }
   else if (result==HAL_TIMEOUT)
   {
     printf("Reception timed out\r\n");
   }
   else
   {
     printf("Error in reception\r\n");
   }

   HAL_Delay(3000);
  }

}

Sure! Here’s how you can frame the email in English:


Subject: Assistance Needed with UART Communication Between Nucleo-F103RB and RAK3272S Breakout Board

Dear [Recipient’s Name],

I hope this email finds you well.

I am currently working on a project involving UART communication between an STM32 Nucleo-F103RB board and a RAK3272S Breakout Board. My goal is to send AT commands from the Nucleo board and receive the response from the RAK3272S Breakout Board, displaying the result on the serial monitor.

I have written the following code, but I am facing an issue where the expected response from the RAK3272S Breakout Board is not being displayed. Below is the code I am using:

코드 복사

#include "main.h"
#include "string.h"
#include "stdio.h"

UART_HandleTypeDef huart2;

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

int main(void)
{

  HAL_Init();

  SystemClock_Config();

  MX_GPIO_Init();
  MX_USART2_UART_Init();

  uint8_t at_command = "Hello\n";
  uint8_t rx_buffer[256];

  HAL_StatusTypeDef result;

  while (1)
  {
   HAL_UART_Transmit(&huart2, at_command, sizeof(at_command), 1000);
   memset(rx_buffer, 0, sizeof(rx_buffer));

   result = HAL_UART_Receive(&huart2, rx_buffer, sizeof(rx_buffer), HAL_MAX_DELAY);

   if (result == HAL_OK)
   {
      HAL_UART_Transmit(&huart2, rx_buffer, sizeof(rx_buffer), HAL_MAX_DELAY); // send received data
   }
   else if (result == HAL_TIMEOUT)
   {
     printf("Reception timed out\r\n");
   }
   else
   {
     printf("Error in reception\r\n");
   }

   HAL_Delay(3000);
  }

}

In this code, I am trying to send an AT command to the RAK3272S Breakout Board via UART2 and then receive and print the response. However, it seems that the response is not being captured or displayed correctly.

Could you please advise on what modifications or additional code might be necessary to correctly receive and display the AT command response from the RAK3272S Breakout Board? For example, if there is a specific format required for the AT command (e.g., `\r\n`) or any other considerations I should be aware of when parsing and transmitting data.

Thank you in advance for your help. I look forward to your guidance.

What speed is the UART setup on your Nucleo? I don’t see any UART settings in your code.

It should be 115200 Baud, 8N1

To which UART on the RAK3172 do you connect? By default AT commands are on UART2 pins.

Did you cross RX/TX lines? RX on RAK3172 should go to TX of the Nucleo.

Are the UART levels 3.3V on the Nucleo?

Did you try to communicate with the RAK3172 from a computer with a USB/UART converter and a terminal application or WisToolBox?

As you mentioned, I configured the settings accordingly. I set up the UART with RX connected to TX and TX connected to RX, and connected it at 3.3V. I used the SerialPortMon program to check the results. I’m not sure if it will help, but I’m attaching our entire code.

/* USER CODE BEGIN Header */
/**
  ******************************************************************************
  * @file           : main.c
  * @brief          : Main program body
  ******************************************************************************
  * @attention
  *
  * Copyright (c) 2024 STMicroelectronics.
  * All rights reserved.
  *
  * This software is licensed under terms that can be found in the LICENSE file
  * in the root directory of this software component.
  * If no LICENSE file comes with this software, it is provided AS-IS.
  *
  ******************************************************************************
  */
/* USER CODE END Header */
/* Includes ------------------------------------------------------------------*/
#include "main.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 ---------------------------------------------------------*/
UART_HandleTypeDef huart2;

/* USER CODE BEGIN PV */

/* USER CODE END PV */

/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_USART2_UART_Init(void);
/* USER CODE BEGIN PFP */

/* 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 */
	uint8_t at_command = "hello";
	uint8_t rx_buffer[256];
	  HAL_StatusTypeDef result;

  /* 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_USART2_UART_Init();
  /* USER CODE BEGIN 2 */

  /* USER CODE END 2 */

  /* Infinite loop */
  /* USER CODE BEGIN WHILE */
  while (1)
  {
	  HAL_UART_Transmit(&huart2, at_command, sizeof(at_command), 1000);
	  memset(rx_buffer, 0, sizeof(rx_buffer));
	        result = HAL_UART_Receive(&huart2, rx_buffer, sizeof(rx_buffer), HAL_MAX_DELAY);
	        if (result == HAL_OK)
	        {
	           HAL_UART_Transmit(&huart2, rx_buffer, sizeof(rx_buffer), HAL_MAX_DELAY); // send received data
	        }
	        else if (result==HAL_TIMEOUT)
	        {
	          printf("Reception timed out\r\n");
	        }
	        else
	        {
	          printf("Error in reception\r\n");
	        }

	        HAL_Delay(3000);
    /* USER CODE END WHILE */

    /* USER CODE BEGIN 3 */
  }
  /* USER CODE END 3 */
}

/**
  * @brief System Clock Configuration
  * @retval None
  */
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_HSI;
  RCC_OscInitStruct.HSIState = RCC_HSI_ON;
  RCC_OscInitStruct.HSICalibrationValue = RCC_HSICALIBRATION_DEFAULT;
  RCC_OscInitStruct.PLL.PLLState = RCC_PLL_ON;
  RCC_OscInitStruct.PLL.PLLSource = RCC_PLLSOURCE_HSI_DIV2;
  RCC_OscInitStruct.PLL.PLLMUL = RCC_PLL_MUL16;
  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();
  }
}

/**
  * @brief USART2 Initialization Function
  * @param None
  * @retval None
  */
static void MX_USART2_UART_Init(void)
{

  /* USER CODE BEGIN USART2_Init 0 */

  /* USER CODE END USART2_Init 0 */

  /* USER CODE BEGIN USART2_Init 1 */

  /* USER CODE END USART2_Init 1 */
  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();
  }
  /* USER CODE BEGIN USART2_Init 2 */

  /* USER CODE END USART2_Init 2 */

}

/**
  * @brief GPIO Initialization Function
  * @param None
  * @retval None
  */
static void MX_GPIO_Init(void)
{
  GPIO_InitTypeDef GPIO_InitStruct = {0};
/* USER CODE BEGIN MX_GPIO_Init_1 */
/* USER CODE END MX_GPIO_Init_1 */

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

  /*Configure GPIO pin Output Level */
  HAL_GPIO_WritePin(LD2_GPIO_Port, LD2_Pin, GPIO_PIN_RESET);

  /*Configure GPIO pin : B1_Pin */
  GPIO_InitStruct.Pin = B1_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_IT_RISING;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  HAL_GPIO_Init(B1_GPIO_Port, &GPIO_InitStruct);

  /*Configure GPIO pin : LD2_Pin */
  GPIO_InitStruct.Pin = LD2_Pin;
  GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
  GPIO_InitStruct.Pull = GPIO_NOPULL;
  GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
  HAL_GPIO_Init(LD2_GPIO_Port, &GPIO_InitStruct);

  /* EXTI interrupt init*/
  HAL_NVIC_SetPriority(EXTI15_10_IRQn, 0, 0);
  HAL_NVIC_EnableIRQ(EXTI15_10_IRQn);

/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}

/* USER CODE BEGIN 4 */

/* 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 */
  __disable_irq();
  while (1)
  {
  }
  /* 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,
     ex: printf("Wrong parameters value: file %s on line %d\r\n", file, line) */
  /* USER CODE END 6 */
}
#endif /* USE_FULL_ASSERT */

To which of the two UART of the RAK3172 did you connect?

Only UART2 does support AT commands by default.
UART1 has to be setup by a custom firmware to support AT commands and it does not work in low power mode.