这篇文章,我们来测试一下STM32U3C5单片机的超低功耗模式。对于U系列单片机,超低功耗算是这个单片机的核心卖点之一,得益于出色的近阈值技术,使得U系列单片机具有出色的的功耗表现。所以本篇文章我们将对进入sleep、stop0、 stop1、Stop2、Stop3、 standby和shutdown模式下的功耗表现进行评测。

先介绍一下硬件部分:首先Nucleo板卡加上一个自制的数码管模块,需要使用上面的3个按键,分别对应切换模式、进入低功耗和专用退出低功耗。板子上自带的user按键配置成中断按键。万能表使用uA级别电流档,从J5排针串入电路的总回路中,这个排针是专门给MCU供电的。所以从这里来对功耗进行测试。值得注意的是,U3系列单片机的低功耗模式分成两大类,第一类是从sleep至stop2,它采用任意中断或任意事件就可以唤醒;从Stop3开始至shutdown, 是需要配置专用唤醒引脚才可以对单片机进行唤醒的。值得注意的是,如果进入standby或shutdown模式下,该模式会使单片机内RAM发生丢失,也就是说如果使用这两种低功耗模式,唤醒后程序会从头执行。这个在我们程序中也会体现出来。接下来我们来开始测试。简单介绍一下怎么样才能进入对应的低功耗模式。首先打开串口,按下模式选择按键,当模式选择为0的时候就是进入sleep,然后以此类推。在确认好要进什么模式的情况下,按下第二个按键,就是可以让程序进入对应的低功耗模式。


此时就可以读取万用表的数值了。

这里我们用Stop0模式录制一个GIF来示意。剩下低功耗模式进入过程和这个是一致的,无非就是按了几次按键,对应进入什么样的低功耗模式,这里就不过多演示。我们直接看我测试出来的结果。

运行模式

Sleep模式

Stop0模式

Stop1模式

Stop2模式

Stop3模式

Standby模式

Shutdown模式
当然,在这里我们值得注意的是,我的单片机是运行在使用MSIS内部振荡源、 3.3伏情况下进行工作的。不同场景、工况、时钟配置、外设开启情况以及批次的单片机可能会存在差异,此测试仅针对我手上的这一块板子来进行的。

这里我还会演示进入shutdown模式并唤醒,可以看到我在程序最开始的时候让绿色LED灯闪了5次,然后蓝色LED灯连这个来回闪烁。但是一旦进入shutdown并唤醒后,你会发现程序从头执行,绿色LED闪烁了5次。程序和CubeMX的配置我会放在文章的末尾,大家可以看一下我的程序,然后配置一套一样的出来。
配置相关如下:

GPIO配置

唤醒引脚配置

串口配置

中断配置

时钟树配置
程序相关如下:(记得把两个中断回调函数放到it里面,这样才会启用中断!)
/* 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"
#include "usart.h"
#include "gpio.h"
/* Private includes ----------------------------------------------------------*/
/* USER CODE BEGIN Includes */
#include "stdio.h"
/* 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 */
int i;
/* USER CODE END PV */
/* Private function prototypes -----------------------------------------------*/
void SystemClock_Config(void);
/* USER CODE BEGIN PFP */
void Sleep_Mode(void);
void Stop0_Mode(void);
void Stop1_Mode(void);
void Stop2_Mode(void);
void Stop3_Mode(void);
void Standby_Mode(void);
void Shutdown_Mode(void);
void LED_Blink(uint8_t Num,int ms);
void EXTI1_IRQHandlerCallBack(void);
void EXTI13_IRQHandlerCallBack(void);
/* USER CODE END PFP */
/* Private user code ---------------------------------------------------------*/
/* USER CODE BEGIN 0 */
void EXTI1_IRQHandlerCallBack(void){
i=i+1;
if(i>6){
i=0;
}
printf("\ni=%d\n",i);
}
void EXTI13_IRQHandlerCallBack(void){
HAL_GPIO_TogglePin(LD2_GPIO_Port,LD2_Pin);
}
/* 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_USART1_UART_Init();
/* USER CODE BEGIN 2 */
LED_Blink(5,100);
printf("ST Chinese Forum Evaluation Plan\r\n");
printf("Board Mode:Nucleo-U3C5\r\n");
printf("Demo2:LowPower_Mode\r\n");
printf("Reviewer:Xiang Zhong Bli:C70E\r\n");
/* USER CODE END 2 */
/* Infinite loop */
/* USER CODE BEGIN WHILE */
while (1)
{
while(HAL_GPIO_ReadPin(In_Low_Power_GPIO_Port,In_Low_Power_Pin)==GPIO_PIN_RESET){
HAL_Delay(10);
if(HAL_GPIO_ReadPin(In_Low_Power_GPIO_Port,In_Low_Power_Pin)==GPIO_PIN_SET){
switch(i){
case 0:
printf("Sleep_Mode");
HAL_GPIO_WritePin (LD1_GPIO_Port,LD1_Pin,GPIO_PIN_RESET);
HAL_GPIO_WritePin (LD2_GPIO_Port,LD2_Pin,GPIO_PIN_RESET);
HAL_GPIO_WritePin (LD3_GPIO_Port,LD3_Pin,GPIO_PIN_RESET);
Sleep_Mode();
break;
case 1:
HAL_GPIO_WritePin (LD1_GPIO_Port,LD1_Pin,GPIO_PIN_RESET);
HAL_GPIO_WritePin (LD2_GPIO_Port,LD2_Pin,GPIO_PIN_RESET);
HAL_GPIO_WritePin (LD3_GPIO_Port,LD3_Pin,GPIO_PIN_RESET);
printf("Stop0_Mode");
Stop0_Mode();
break;
case 2:
HAL_GPIO_WritePin (LD1_GPIO_Port,LD1_Pin,GPIO_PIN_RESET);
HAL_GPIO_WritePin (LD2_GPIO_Port,LD2_Pin,GPIO_PIN_RESET);
HAL_GPIO_WritePin (LD3_GPIO_Port,LD3_Pin,GPIO_PIN_RESET);
printf("Stop1_Mode");
Stop1_Mode();
break;
case 3:
HAL_GPIO_WritePin (LD1_GPIO_Port,LD1_Pin,GPIO_PIN_RESET);
HAL_GPIO_WritePin (LD2_GPIO_Port,LD2_Pin,GPIO_PIN_RESET);
HAL_GPIO_WritePin (LD3_GPIO_Port,LD3_Pin,GPIO_PIN_RESET);
printf("Stop2_Mode");
Stop2_Mode();
break;
case 4:
HAL_GPIO_WritePin (LD1_GPIO_Port,LD1_Pin,GPIO_PIN_RESET);
HAL_GPIO_WritePin (LD2_GPIO_Port,LD2_Pin,GPIO_PIN_RESET);
HAL_GPIO_WritePin (LD3_GPIO_Port,LD3_Pin,GPIO_PIN_RESET);
printf("Stop3_Mode");
Stop3_Mode();
break;
case 5:
HAL_GPIO_WritePin (LD1_GPIO_Port,LD1_Pin,GPIO_PIN_RESET);
HAL_GPIO_WritePin (LD2_GPIO_Port,LD2_Pin,GPIO_PIN_RESET);
HAL_GPIO_WritePin (LD3_GPIO_Port,LD3_Pin,GPIO_PIN_RESET);
printf("Standby_Mode");
Standby_Mode();
break;
case 6:
HAL_GPIO_WritePin (LD1_GPIO_Port,LD1_Pin,GPIO_PIN_RESET);
HAL_GPIO_WritePin (LD2_GPIO_Port,LD2_Pin,GPIO_PIN_RESET);
HAL_GPIO_WritePin (LD3_GPIO_Port,LD3_Pin,GPIO_PIN_RESET);
printf("Shutdown_Mode");
Shutdown_Mode();
break;
}
}
}
HAL_GPIO_WritePin (LD3_GPIO_Port,LD3_Pin,GPIO_PIN_RESET);
HAL_Delay(500);
HAL_GPIO_WritePin (LD3_GPIO_Port,LD3_Pin,GPIO_PIN_SET);
HAL_Delay(500);
/* 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 the System Power Supply
*/
if (HAL_PWREx_ConfigSupply(PWR_SMPS_SUPPLY) != HAL_OK)
{
Error_Handler();
}
/** Configure the main internal regulator output voltage
*/
if (HAL_PWREx_ControlVoltageScaling(PWR_REGULATOR_VOLTAGE_SCALE2) != HAL_OK)
{
Error_Handler();
}
/** Initializes the CPU, AHB and APB buses clocks
*/
RCC_OscInitStruct.OscillatorType = RCC_OSCILLATORTYPE_MSIS;
RCC_OscInitStruct.MSISState = RCC_MSI_ON;
RCC_OscInitStruct.MSISSource = RCC_MSI_RC0;
RCC_OscInitStruct.MSISDiv = RCC_MSI_DIV8;
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_CLOCKTYPE_PCLK3;
RCC_ClkInitStruct.SYSCLKSource = RCC_SYSCLKSOURCE_MSIS;
RCC_ClkInitStruct.AHBCLKDivider = RCC_SYSCLK_DIV1;
RCC_ClkInitStruct.APB1CLKDivider = RCC_HCLK_DIV1;
RCC_ClkInitStruct.APB2CLKDivider = RCC_HCLK_DIV1;
RCC_ClkInitStruct.APB3CLKDivider = RCC_HCLK_DIV1;
if (HAL_RCC_ClockConfig(&RCC_ClkInitStruct, FLASH_LATENCY_0) != HAL_OK)
{
Error_Handler();
}
}
/* USER CODE BEGIN 4 */
void Sleep_Mode(void){
HAL_SuspendTick();
HAL_PWR_EnterSLEEPMode (PWR_MAINREGULATOR_ON ,PWR_SLEEPENTRY_WFI );
HAL_ResumeTick();
}
void Stop0_Mode(void){
HAL_SuspendTick();
HAL_PWR_EnterSTOPMode(PWR_LOWPOWERMODE_STOP0, PWR_STOPENTRY_WFI);
HAL_ResumeTick();
SystemClock_Config();
}
void Stop1_Mode(void){
HAL_SuspendTick();
HAL_PWR_EnterSTOPMode(PWR_LOWPOWERMODE_STOP1, PWR_STOPENTRY_WFI);
HAL_ResumeTick();
SystemClock_Config();
}
void Stop2_Mode(void){
HAL_SuspendTick();
HAL_PWR_EnterSTOPMode(PWR_LOWPOWERMODE_STOP2, PWR_STOPENTRY_WFI);
HAL_ResumeTick();
SystemClock_Config();
}
void Stop3_Mode(void){
HAL_PWR_GetClearWakeupSource();
HAL_PWR_EnableWakeUpLine(PWR_WAKEUP_LINE1,PWR_WAKEUP_SELECT_0,PWR_WAKEUP_POLARITY_LOW); //
HAL_SuspendTick();
HAL_PWR_EnterSTOPMode(PWR_LOWPOWERMODE_STOP3, PWR_STOPENTRY_WFI);
i=4;
__HAL_PWR_CLEAR_FLAG(PWR_WAKEUP_FLAG1);
HAL_ResumeTick();
SystemClock_Config();
}
void Standby_Mode(void){
HAL_PWR_GetClearWakeupSource();
HAL_PWR_EnableWakeUpLine(PWR_WAKEUP_LINE1,PWR_WAKEUP_SELECT_0,PWR_WAKEUP_POLARITY_LOW); //
HAL_PWR_EnterSTANDBYMode();
__HAL_PWR_CLEAR_FLAG(PWR_WAKEUP_FLAG1);
}
void Shutdown_Mode(void){
HAL_PWR_GetClearWakeupSource();
HAL_PWR_EnableWakeUpLine(PWR_WAKEUP_LINE1,PWR_WAKEUP_SELECT_0,PWR_WAKEUP_POLARITY_LOW); //
HAL_PWREx_EnterSHUTDOWNMode();
__HAL_PWR_CLEAR_FLAG(PWR_WAKEUP_FLAG1);
}
void LED_Blink(uint8_t Num,int ms){
for(uint8_t i=0;i<Num;i++){
HAL_GPIO_WritePin (LD1_GPIO_Port,LD1_Pin,GPIO_PIN_SET);
HAL_Delay(ms);
HAL_GPIO_WritePin (LD1_GPIO_Port,LD1_Pin,GPIO_PIN_RESET);
HAL_Delay(ms);
}
}
int fputc(int ch,FILE *f)
{
HAL_UART_Transmit(&huart1,(uint8_t *)&ch,1,0xFFFF);
return ch;
}
/* 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 */