When using the deep sleep functionality on several ESP-01 boards, the boards require two resets in order to wake up properly (regardless of whether the resets are done by manually bridging the rst pin or by soldering a wire to do it from an interrupt). The boards do wake up and print some text automatically, but they do not run their firmware/code.

#include <ESP8266WiFi.h>
void setup() {

    //pinMode(LED_BUILTIN, OUTPUT);     // Initialize the LED_BUILTIN pin as an output
    //digitalWrite(LED_BUILTIN, HIGH);  // Turn the LED off (gpio @ high= off)

    ESP.deepSleep(2000000, WAKE_RF_DEFAULT );

void loop() {

I have not been able to just wake the board and run the code like most examples on the web intend to work, so I suppose the problem is not with this code.

On a successful wake up, the serial output looks like this:

 ets Jan  8 2013,rst cause:2, boot mode:(3,6)
load 0x4010f000, len 3456, room 16 
tail 0
chksum 0x84
csum 0x84


After the first reset, the board does indeed wake up, but it does not run it's code. It only prints this

 ets Jan  8 2013,rst cause:2, boot mode:(3,6)

And then hangs there. After another reset, it successfully runs it's code.

This issue persists across all the esp 01 boards i own, and i have tried pulling UP and DOWN almost every combination of pins recommended. The line that is printed in the fauly cases does indeed say it is booting in the right mode, but still the code does not run, nor mine nor the one that runs before mine

  • Had you tried ESP.deepSleep(2000000); instead of ESP.deepSleepInstant(2000000, WAKE_RF_DEFAULT ); ? Commented Jun 27, 2020 at 15:33
  • @fabiuz7 yes, i tried deepSleepInstant to test if it had any different results from deepSleep, with no effect
    – sassoPera
    Commented Jun 27, 2020 at 15:36
  • Are you using this board ? It seems not exposing the pin 16, required to make the deep sleep working. mouser.it/ProductDetail/SparkFun/… Commented Jun 27, 2020 at 15:46
  • I've tested your code on a Wemos D1 mini and it works as expected Commented Jun 27, 2020 at 15:48
  • 1
    Yeah, i'm sorry but i specifically described that i got weird behaviours even when using the RESET pin. This default answer of "oh you just didn't know to solder a wire" is what made me go insane at the time, because it's repeated like a mantra even to completely unrelated issues.
    – sassoPera
    Commented Aug 8, 2021 at 14:54

1 Answer 1


What sasso is describing is classic Deep Sleep Zombie mode. There's someone else here with ESP-01 boards with the same issue. I'd bet you got your boards in blister packs from Inland. I didn't see any ESP-01 boards from Inland at my local computer store, only ESP-01S, and that one works with Deep Sleep just fine. I only bought the one for a test. I believe it's the Flash chip, but we haven't proven that yet. I have plenty of Winbond flash in case I find a board that goes zombie, and can prove or disprove my theory. I have 8 different types of boards and modules, and all come out of Deep Sleep correctly.

edit: If the pic at Ali is correct, the Puya Flash shouldn't be causing an issue, presuming it's real and not a clone. Half the time the pics are only 'representative examples' of what they ship. The ESP8266 Arduino core has supported Puya for a while now. Also, on sober reflection the Inland package I bought said ESP-01S, and it's actually an ESP-01 (false advertising). I looked closer and didn't see the pull-up resistors. :-(

If you're powering it from that USB programmer board, it should work. If you have a separate 3.3V supply, I'd be suspicious of the supply. The current spikes as the ESP is booting will cause many switching supplies to drop below 2V briefly, and the ESP goes insane. Without having a zombie in front of me, I'm at a loss to go a lot further as my 'scope leads aren't that long.

  • Thank you very much for answering, the fact that almost no one ever aknowledged this problem around the net was driving me crazy. I got 8 boards from aliexpress from china, none of them works after deep sleep. I recentrly tried ordering a couple more to see if it was an hardware issue or not. Let me know if you need any info on the boards i got
    – sassoPera
    Commented Dec 16, 2020 at 10:31
  • Do you have the ali link, or a very good photo of the top of the board so that I can read the ID on the Flash chip? I suspect it says T25S80 (supposedly Bright Moon Semi) which you can also get by doing Serial.println(ESP.getFlashChipId(), HEX); after you've started the serial port. I get 14605E with what I think is a Bright Moon chip, although the manufacturer ID doesn't match their datasheet. Commented Dec 19, 2020 at 18:54
  • aliexpress.com/item/… this is where i got them, the ESP-01S variety
    – sassoPera
    Commented Dec 20, 2020 at 0:21
  • Any update about that one @KrazyOldGuy ? I have the same issue with a ESP12F from aliexpress. FlashChipId is 1660C4 for me (but i cant have a look at the flash chip because there is a metal cover on the board.
    – Janosch
    Commented May 7 at 22:02

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