ESP8266 Community Forum

Hi.
I'm new to electronics and ESP8266 and I am sorry for this huge post but I want to understand what I did wrong because I want to play with ESP8266 more and don't want to kill more chips for reason I don't know.

My hardware:
ESP-12F
Home-made board with sensors and relay to play with (photo: https://i.imgur.com/Ie80oIK.jpg )
LM317 voltage regulator configured to ~3.25V but for this post I used external home-made regulated power supply configured to ~3.4V
I soldered 220uF and 100nF capacitors near power input for this post
Relay have diode to protect board from voltage spikes under board, I use "1N4001" diode, but maybe its too slow and voltage spikes got to ESP8266.
But on other hand my problems started before I clicked relay for first time.

So my story sounds like this:
About half year ago I made that board and flashed it with NodeMCU. It was great until I configured WiFi and rebooted it. It entered infinity reboot with random errors (you can see them below) (not NodeMCU syntax errors).
I thought I killed it, but after re-flash same code was working fine.
It was running for about a week and clicking relay thousands of times and it was great. But every time I change some file there was risk entering infinity reboot or random garbage/error.
Re-flashing was helping for some time, but few days ago I again started to play with board and it died after some file changes and reboot.
Now I can not reflash it anymore.

I have "nodemcu-master-15-modules-2017-11-24-03-43-03-integer.bin" that was working before.
So I try to flash it:


Again:


Again:


Again:


Again:

Now I reboot and look in serial console at speed 115200

Reboot:

And stops. Current is 0.14A at 3.35V

Reboot again:

And stops. Current is 0.18A at 3.35V

And again:

And stops. Current is 0.15A at 3.36V

And again:

And stops. Current is 0.06A at 3.36V

So I get random results on every reboot.
But even with MD5 error I can get this after few reboots

But it not helps, still no success. And "Formatting file system. Please wait..." can repeat after reboots, so I think it fails to format.

Now I want to try to read flash 20 times.


I saw errors:



Now MD5:

Sooo... Uhm...

Diff:
(command found in google)

For some reason all corrupted addresses have x00x at address. That should mean something. Maybe.
In all dumps 00000004 changed from 0x00 to 0x40
I attempted to flash 4 byte file with bytes from original nodemcu .bin file but something erased 0x5-0xFFF with zeros, but 0x0-0x4 was fine and 0x4 was not changed this time.
Interesting.
So I generated random file

And 2 times got MD5 error.
So flash is dead.
...or not?

I made 16 files 609104 bytes each.
First filled with 0x00 0x00 0x00...
Second filled with 0x11 0x11 0x11...
...
Last filled with 0xFF 0xFF 0xFF...

Flashing is 0.1 second due to compression and no MD5 errors.
And reading is 54.7 seconds (as always)

One time I managed to get error


But after everything is done, all MD5 matched.

Non-compessed files corrupted even if flash was success and compressable files are fine.
I rebooted ESP8266 100 times (yes I counted) and 0xFF still dumps with same MD5
Then I generated random file again using /dev/urandom

Now read and diff:

Flashing NodeMCU I tried different flashing tools under windows and different firmware and none of them works.
I tried different power sources, nothing changes.
I do have another ESP-12F but I do not want to solder it to kill it too without understanding why.
Please help me to understand what is happening and why.

Update:
Trying to get more information about problem and trying everything I can think of I did something.
I have Chinese clone of selae logic analyzer so I soldered it to memory chip (and it kinda works actually, but I understand nothing https://i.imgur.com/mBRYFIz.png )
And everything started to flash normally. Dump shows only one byte at 00000004 changed. Maybe it should be like that since it changes in all my NodeMCU flash tests.
After reboot I got:

Now I de-solder selae logic analyzer.
And try to flash again:

And reboot:

Working. Trying 5 random files.


Reading


MD5 is marching. Never happened before.
Now second file

And after that I have no activity on my board. Blue led is not blinking, reset button does nothing, current is 10mA at 3.28V (I think its my pull up/down resistors on board)
I can't make it enter flash mode anymore.
Correction: blue LED rarely blinks and some data is sending, in console on speed 115200 I see it like this: https://i.imgur.com/Eold3vA.png
GPIO0 is pulled to GND
I think I will try erase flash chip with arduino later. Google says it is possible.
Any ideas?

Another update:
(This message should be 3rd in thread, not sure how moderator approving works on this forum, hope my 2nd message will be not overwrited)
I tried to make blue led blink for long time but nothing helped.
So I de-soldered memory chip to try to erase it with arduino and blue led started reacting to reset button.
I pressed down memory chip on pads holding by finger and blue led is reacting. I downloaded random_2.bin and MD5 matches. I flashed it again, no problem. Powered on/off, pressed reset, flash button, no problem, it works.
Downloaded again, again MD5 match.
Soldered memory chip back, flashed with NodeMCU, it works. Rebooted 100 times (I counted) and 100/100 NodeMCU loaded successfully.

So something here is broken in random moments.
If it is memory, then why ESP8266 was not loading at all? It loads even without chip.
If it is ESP8266 itself, then how soldering logic analyzer helped?
But looks like problems appearing only when some files modified on flash. I'm sure my board will brick itself again when I will write some files on it and fix will be re-soldering memory chip.
Maybe its reacting to heat like broken GPU computer video cards.
Still I would like to know how I broke it and how to not repeat this in future. Not sure if universe have answer to that question.

I hate to see this very detailed post to go unanswered, but then again i think you answered it yourself. Your memory appears to be not 100%. I have quite some boards that work... until they're not. While these are presoldered dev-boards with all the circuitry on board that doesn't in any way prevent them from showing exactly what you report. It might be a combination of small power fluctuations, random(ish) power draws and a flash chip from the "good enough" pile. Sorry to be of no help, but i think you did as much as you could and there is no sensible way to prevent this sort of thing other than the precautions you already took. Others with more knowledge may have more input, but based on my exp sometimes the universe is just out to get you(r ESP)