I am attempting to implement a light sleep mode on an esp8266 (feather huzzah) which, when a button is pressed, wakes the system up so that it can continue its normal task.

I cobbled together some code from this post, which I've slightly modified:

#include <ESP8266WiFi.h>
#include <WiFiUdp.h>
#define WAKE_PIN 5

extern "C" {
    #include "gpio.h"

extern "C" {
    #include "user_interface.h"

void setup(){

    gpio_init(); // Init GPIO pins

void loop(){
    Serial.println("Do something...");
    delay(500); //random delay for that stuff to be done

    if(!digitalRead(WAKE_PIN)){ //if we don't detect pin, sleep


void sleep(){
    Serial.println("Going to sleep...");
    wifi_fpm_set_sleep_type(LIGHT_SLEEP_T); // set sleep type
    gpio_pin_wakeup_enable(GPIO_ID_PIN(WAKE_PIN), GPIO_PIN_INTR_LOLEVEL);  //LO OR HI?
    wifi_fpm_open(); // Enables force sleep
    wifi_fpm_do_sleep(5000); //Sleep for short time
    Serial.println("Woke up!");

Here is how I have things wired:

enter image description here

So the setup function works as expected, as well as "do something". The button reads high (1) when it is unpressed, and when I push it, it reads low (0) - which sends the ESP to sleep. In the serial monitor, I see:

Going to sleep...
Soft WDT reset

ctx: cont 
sp: 3ffef7a0 end: 3ffef9a0 offset: 01b0

3ffef950:  0001260d 00000600 3ffee970 4021fc84  
3ffef960:  00001388 402020ba 402020b1 402020a1  
3ffef970:  00000000 00000000 3ffee944 40202115  
3ffef980:  3fffdad0 00000000 3ffee968 402027d4  
3ffef990:  feefeffe feefeffe 3ffee980 40100710  

 ets Jan  8 2013,rst cause:2, boot mode:(1,6)

 ets Jan  8 2013,rst cause:4, boot mode:(1,6)

wdt reset

I'm not very experienced with Arduino or Electric Engineering, so I'm not exactly sure what is happening vs. what should happen, but this is my interpretation:

I read somewhere that reset causes are as follows:

reset causes:
    1: normal boot
    2: reset pin
    3: software reset
    4: watchdog reset

boot device:
    1: ram
    3: flash

In which case, if soft reset is considered light sleep for the esp, then the rst cause:2 is expected behavior, as it means it was triggered by pin 5. The rst cause: 4 i'm not sure about though - watchdog reset. Seems to be a protective mechanism for the device, in which case maybe the reset of this must coincide with the reset triggered by sleep mode and is normal? Or does it indicate a crash? In any case, I have no idea what all the stack stuff is, but the system does not restart - I cannot get any further readings from the serial monitor after this.

I'm not sure whether GPIO_PIN_INTR_LOLEVEL should be high or low - I couldn't find documentation on this (though I did see it in the [GPIO header source file] on git.5

I read something where someone else had a similar problem and someone made a reference to adding resistors and making sure GPIO 0 should be high, and 15 should be low. The link they posted was dead, but it made me think of something I read about deep sleep, in which you have to wire RST to 0. I actually tried running a wire between RST and holding to the #0 pad that's right by the USB port on the feather huzzah, and after that, the code would actually go to sleep, then wake itself up automatically and resume the normal loop function - but what I want is for only the button to wake up the ESP.

I'm stuck from here. Anyone have any ideas of what might be happening and how to fix it?

  • what does #include "gpio.h" do? – dandavis Jun 25 '18 at 21:27
  • Includes the GPIO library which allows access to gpio_pin_wakeup_enable - as far as I know. – mheavers Jun 25 '18 at 21:38

You can make the ESP8266 wake from deep sleep by just pulsing RST low briefly. Crudely you can just use your switch to connect it to GND perhaps with a pullup resistor to +v. If you want to be a bit more elegant you could use a small capacitor to smooth out the switch bounce so your code only restarts once. I use this on an ESP8266 that is solar-powered. Most of the time it is in deep-sleep. It wakes up, connects to MQTT and deep sleeps again only when the sensor it is monitoring changes state.

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