I’m facing a recurring issue with the LSE (Low-Speed External) oscillator on several new Wio-E5 modules used in my custom PCB design, and I’d like some help verifying if this is a hardware or firmware-level change in recent production batches.
I have designed a custom PCB based on the Seeed Studio Wio-E5 reference design (RHF0M0E5-HF22-BOM20211111).
This design was successfully used in a LoRa application, where several boards from an earlier batch of Wio-E5 modules worked flawlessly — no issues with clock startup or LoRa communication.
Recently, I procured a new batch of Wio-E5 modules and assembled the same PCB design.
However, all of these new boards (3 tested so far) consistently fail during LSE initialization.
Observed Behavior
When running the firmware (based on the Seeed Wio-E5 GitHub repo: danak6jq/Seeed-LoRa-E5), the code consistently gets stuck in:
while (LL_RCC_LSE_IsReady() == 0U)
{
if ((HAL_GetTick() - tickstart) > RCC_LSE_TIMEOUT_VALUE)
{
return HAL_TIMEOUT;
}
}
This results in an LSE timeout — the LSERDY bit never gets set.
I also attempted to switch to LSI as the RTC clock source, but even then, the MCU seems to get stuck in the same section of the initialization routine (HAL_RCC_OscConfig()).
What I’ve verified:
- PCB layout and passives are identical to the working design.
- LSE drive set to high, backup domain access OK.
- CubeMX configured for LSE crystal, PC14/PC15 mapped correctly.
- Added diagnostic flags — confirms
LSEON set but LSERDY never ready.
- Tested multiple units — all new modules fail, old ones OK.
Any insights from Seeed engineers or anyone who has experienced similar behavior with newer Wio-E5 batches would be greatly appreciated.
Thanks in advance!
Are you getting communications from the chip? is it hanging up or are you just not able to hear what it is saying?
No it is getting stuck at the LSE timer initi without it sys clock keeps on checking if the LSE timer is ready or not in a loop so the code does’nt run further
Has anyone found a solution? I am having a similar problem when trying to make a simple Blink sketch using the RTC timer hooked up to the LSE. This sketch works fine with the LSI
/* USER CODE BEGIN Header */
/**
******************************************************************************
* @file : main.c
* @brief : Main program body
******************************************************************************
* @attention
*
* Copyright (c) 2026 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 ---------------------------------------------------------*/
RTC_HandleTypeDef hrtc;
/* USER CODE BEGIN PV */
/* USER CODE END PV */
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
static void MX_GPIO_Init(void);
static void MX_RTC_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 */
/* 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_RTC_Init();
/* USER CODE BEGIN 2 */
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
/* 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};
/** Configure LSE Drive Capability
*/
HAL_PWR_EnableBkUpAccess();
__HAL_RCC_LSEDRIVE_CONFIG(RCC_LSEDRIVE_LOW);
/** Configure the main internal regulator output voltage
*/
__HAL_PWR_VOLTAGESCALING_CONFIG(PWR_REGULATOR_VOLTAGE_SCALE2);
/** Initializes the CPU, AHB and APB buses clocks
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_LSE|RCC_OSCILLATORTYPE_MSI;
RCC_OscInitStruct.LSEState = RCC_LSE_ON;
RCC_OscInitStruct.MSIState = RCC_MSI_ON;
RCC_OscInitStruct.MSICalibrationValue = RCC_MSICALIBRATION_DEFAULT;
RCC_OscInitStruct.MSIClockRange = RCC_MSIRANGE_6;
RCC_OscInitStruct.PLL.PLLState = RCC_PLL_NONE;
if (HAL_RCC_OscConfig(&RCC_OscInitStruct) != HAL_OK)
{
Error_Handler();
}
/** Configure the SYSCLKSource, HCLK, PCLK1 and PCLK2 clocks dividers
*/
RCC_ClkInitStruct.ClockType = RCC_CLOCKTYPE_HCLK3|RCC_CLOCKTYPE_HCLK
|RCC_CLOCKTYPE_SYSCLK|RCC_CLOCKTYPE_PCLK1
|RCC_CLOCKTYPE_PCLK2;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_MSI;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
RCC_ClkInitStruct.AHBCLK3Divider = RCC_SYSCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
{
Error_Handler();
}
}
/**
* @brief RTC Initialization Function
* @param None
* @retval None
*/
static void MX_RTC_Init(void)
{
/* USER CODE BEGIN RTC_Init 0 */
/* USER CODE END RTC_Init 0 */
/* USER CODE BEGIN RTC_Init 1 */
/* USER CODE END RTC_Init 1 */
/** Initialize RTC Only
*/
hrtc.Instance = RTC;
hrtc.Init.HourFormat = RTC_HOURFORMAT_24;
hrtc.Init.AsynchPrediv = 127;
hrtc.Init.SynchPrediv = 255;
hrtc.Init.OutPut = RTC_OUTPUT_DISABLE;
hrtc.Init.OutPutRemap = RTC_OUTPUT_REMAP_NONE;
hrtc.Init.OutPutPolarity = RTC_OUTPUT_POLARITY_HIGH;
hrtc.Init.OutPutType = RTC_OUTPUT_TYPE_OPENDRAIN;
hrtc.Init.OutPutPullUp = RTC_OUTPUT_PULLUP_NONE;
hrtc.Init.BinMode = RTC_BINARY_NONE;
if (HAL_RTC_Init(&hrtc) != HAL_OK)
{
Error_Handler();
}
/** Enable the WakeUp
*/
if (HAL_RTCEx_SetWakeUpTimer_IT(&hrtc, 0, RTC_WAKEUPCLOCK_CK_SPRE_16BITS, 0) != HAL_OK)
{
Error_Handler();
}
/* USER CODE BEGIN RTC_Init 2 */
/* USER CODE END RTC_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_GPIOB_CLK_ENABLE();
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(LED_PIN_GPIO_Port, LED_PIN_Pin, GPIO_PIN_SET);
/*Configure GPIO pin Output Level */
HAL_GPIO_WritePin(GPIOB, GPIO_PIN_13, GPIO_PIN_RESET);
/*Configure GPIO pins : LED_PIN_Pin PB13 */
GPIO_InitStruct.Pin = LED_PIN_Pin|GPIO_PIN_13;
GPIO_InitStruct.Mode = GPIO_MODE_OUTPUT_PP;
GPIO_InitStruct.Pull = GPIO_NOPULL;
GPIO_InitStruct.Speed = GPIO_SPEED_FREQ_LOW;
HAL_GPIO_Init(GPIOB, &GPIO_InitStruct);
/* USER CODE BEGIN MX_GPIO_Init_2 */
/* USER CODE END MX_GPIO_Init_2 */
}
/* USER CODE BEGIN 4 */
void HAL_RTCEx_WakeUpTimerEventCallback(RTC_HandleTypeDef *hrtc)
{
/* Toggle the LED connected to LED_PIN_Pin */
HAL_GPIO_TogglePin(LED_PIN_GPIO_Port, LED_PIN_Pin);
}
//void HAL_RTC_AlarmAEventCallback(RTC_HandleTypeDef *hrtc) {
// RTC_AlarmTypeDef sAlarm;
// HAL_RTC_GetAlarm(hrtc,&sAlarm,RTC_ALARM_A,FORMAT_BIN);
// if(sAlarm.AlarmTime.Seconds>58) {
// sAlarm.AlarmTime.Seconds=0;
// }else{
// sAlarm.AlarmTime.Seconds=sAlarm.AlarmTime.Seconds+1;
// }
// while(HAL_RTC_SetAlarm_IT(hrtc, &sAlarm, FORMAT_BIN)!=HAL_OK){}
// HAL_GPIO_TogglePin(GPIOB, GPIO_PIN_3);
//}
/* 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 */