ESP8266 GPIO唤醒浅睡眠异常：触发电平持续时触发硬件看门狗复位

需求说明 #

ESP8266与流量计相连，流量计转动时发送高低电平脉冲。需要实现浅睡眠模式，在流量再次启动时通过GPIO唤醒设备。由于无法确定睡眠开始时GPIO的电平状态，会先读取当前GPIO状态，再将唤醒触发配置为GPIO_PIN_INTR_LOLEVEL或GPIO_PIN_INTR_HILEVEL。

问题现象 #

• 若睡眠时GPIO为低电平，被高电平唤醒后，若GPIO持续保持高电平，约7秒后ESP因硬件看门狗（HW WDT）复位崩溃；
• 若睡眠时GPIO为高电平，被低电平唤醒后，若GPIO持续保持低电平，同样触发HW WDT复位；
• 已知浅睡眠唤醒仅支持脉冲触发的说法，但无法接受唤醒后GPIO不能持续处于特定电平的限制。

已尝试方案 #

• 唤醒后调用wifi_fpm_close()，无效；
• 唤醒后再次睡眠1毫秒并配置其他未使用的GPIO，无效；
• 关闭WiFi、ESP-NOW等功能，极简无WiFi代码仍存在问题；
• 用按键替代流量计测试，按键持续处于与唤醒电平相反的状态时设备崩溃；
• 考虑过搭建硬件电路仅传递单个脉冲，但希望先确认是否存在软件解决方案。

崩溃输出信息 #

19:15:39.318 >  ets Jan  8 2013,rst cause:4, boot mode:(3,7)
19:15:39.321 >
19:15:39.321 > wdt reset
19:15:39.321 > load 0x4010f000, len 3424, room 16
19:15:39.328 > tail 0
19:15:39.329 > chksum 0x2e
19:15:39.329 > load 0x3fff20b8, len 40, room 8
19:15:39.331 > tail 0
19:15:39.331 > chksum 0x2b
19:15:39.334 > csum 0x2b
19:15:39.334 > v00044c80
19:15:39.336 > ~ld

简化测试代码 #

#define DEBOUNCE_INTERVAL 10 //debouncing time in ms for interrupts
#define IDLE_TIME 15 //300 //idle time in sec beyond which the ESP goes to sleep , to be woken up only by a pulse from the meter
#define PULSE_PIN                4  // defines the pin to which the encoder is connected
#define WAKEUP_PIN               14  // defines the pin to which the wakeup signal is connected, in this case it is the same as the encoder pin 
// ************ HASH DEFINES *******************

#include <Arduino.h>
#include "secrets.h"
#include "Debugutils.h"
#include <ESP8266WiFi.h>
#include <user_interface.h> // for RTC memory functions

// ************ GLOBAL OBJECTS/VARIABLES *******************
unsigned int pulses = 0; //stores the no of pulses detected by the sensor, it is reset after SENSOR_UPDATE_INTERVAL
unsigned long last_sleep_time = millis();//stores the no of ms since a message was last published , used to sleep the ESP beyond a certain value
unsigned long idle_time = millis();
volatile unsigned long lastMicros;
// ************ GLOBAL OBJECTS/VARIABLES *******************

void IRAM_ATTR pulseHandler() {
  if((long)(micros() - lastMicros) >= DEBOUNCE_INTERVAL * 1000) {  //note DEBOUNCE_INTERVAL is in ms , so multiply by 1000 for microsec
    pulses += 1;
    lastMicros = micros();
  }
}

void light_sleep(){
    WiFi.mode(WIFI_OFF);  // you must turn the modem off; using disconnect won't work
    // extern os_timer_t* timer_list;
    // timer_list = nullptr;  // stop (but don't disable) the 4 OS timers    
    wifi_fpm_set_sleep_type(LIGHT_SLEEP_T);
    bool wakeup_pin_state = digitalRead(WAKEUP_PIN);
    gpio_pin_wakeup_enable(GPIO_ID_PIN(WAKEUP_PIN), wakeup_pin_state? GPIO_PIN_INTR_LOLEVEL:GPIO_PIN_INTR_HILEVEL);// only LOLEVEL or HILEVEL interrupts work, no edge, that's a CPU limitation
    Serial.printf("CPU going to sleep, pull WAKE_UP_PIN %s to wakeup",wakeup_pin_state?"LOW":"HIGH");Serial.flush();
    wifi_fpm_open();
    wifi_fpm_do_sleep(0xFFFFFFF);  // only 0xFFFFFFF, any other value and it won't disconnect the RTC timer
    delay(10);  // it goes to sleep during this delay() and waits for an interrupt
    Serial.println(F("Woke up!"));  // the interrupt callback hits before this is executed*/
    wifi_fpm_close();  // Disable force sleep mode
    //sometimes the above statement gets printed before actually sleeping off, doesnt happen all the time though
    //But the code works as expected, the ESP sleeps after printing Woke up
 }

void setup() {
  Serial.begin(115200);
  pinMode(WAKEUP_PIN, INPUT_PULLUP);//INPUT_PULLUP
  pinMode(PULSE_PIN, INPUT_PULLUP);
  attachInterrupt(PULSE_PIN, pulseHandler, RISING);

  Serial.println("Setup complete");
}

void loop() {
    idle_time = millis() - last_sleep_time;
    if(idle_time >= IDLE_TIME * 1000)
    {
      Serial.print("going to sleep after being idle for :"); Serial.print(idle_time/1000);Serial.println(" sec");Serial.flush();
      light_sleep();
      //now that we're awake , add the sleep time to the previous value
      last_sleep_time = millis();
    }
    yield();

  }

解决方案 #

问题核心原因：ESP8266浅睡眠的电平触发唤醒机制，在唤醒后如果触发电平持续存在，会不断触发唤醒中断，导致系统无法正常执行看门狗喂狗操作，最终触发HW WDT复位。

软件修复步骤 #

1. 唤醒后立即禁用GPIO唤醒中断：在唤醒后的第一时间关闭之前配置的GPIO唤醒功能，避免持续触发中断请求；
2. 恢复GPIO的正常功能：重新配置GPIO为普通输入或恢复脉冲检测的边缘触发中断。

修改后的light_sleep函数示例：

void light_sleep(){
    WiFi.mode(WIFI_OFF);  
    wifi_fpm_set_sleep_type(LIGHT_SLEEP_T);
    bool wakeup_pin_state = digitalRead(WAKEUP_PIN);
    gpio_pin_wakeup_enable(GPIO_ID_PIN(WAKEUP_PIN), wakeup_pin_state? GPIO_PIN_INTR_LOLEVEL:GPIO_PIN_INTR_HILEVEL);
    Serial.printf("CPU going to sleep, pull WAKE_UP_PIN %s to wakeup",wakeup_pin_state?"LOW":"HIGH");Serial.flush();
    wifi_fpm_open();
    wifi_fpm_do_sleep(0xFFFFFFF);  
    delay(10);  
    Serial.println(F("Woke up!"));  

    // 关键：唤醒后立即禁用GPIO唤醒中断
    gpio_pin_wakeup_disable();
    wifi_fpm_close();  

    // 恢复脉冲检测中断，确保流量计计数功能正常
    detachInterrupt(PULSE_PIN);
    attachInterrupt(PULSE_PIN, pulseHandler, RISING);
 }

额外说明 #

• gpio_pin_wakeup_disable()会关闭所有GPIO的唤醒中断，这是必要步骤，避免持续触发中断占用系统资源；
• 重新附加脉冲检测中断是为了恢复流量计的正常计数，避免唤醒后丢失脉冲信号；
• 后续再次进入浅睡眠时，代码会重新读取GPIO状态并配置唤醒触发条件，不影响重复睡眠逻辑。

替代硬件方案（若软件方案无效） #

• 在流量计输出端增加RC滤波电路，将持续电平转换为短脉冲；
• 使用单稳态触发器，确保唤醒信号仅为单次脉冲，避免持续触发。

内容的提问来源于stack exchange，提问作者Vijay