ESP8266 loss connection after one hour

[MathiasElectroDTU]

Hi
Im using an esp8266 to read from my Kamstrup meter and at first everything worked as it should. But after about an hour my esp bugs out or something and I can't connect to the webserver anymore, even if I reset or unplugs the esp.

The only thing I have done that fixed it was to reflash it, but then it dies again after some time.

[ArnieO]

Schematic / photos?

[MathiasElectroDTU]

I dont have much wiring, but i made a small schematic for my ESP to HAN

Here is a little diagram over my setup. I Run my raspberry inside a docker container

My setup in the webinterface for the ESP, but il write some of the setup stuff here:
Version 2.4.7
hardware Generic ESP8266
maximum buffer of 64, serial 2400 IN8
The two keys for the encryption
IPv6 enable
DCHP ipaddress
No pullup for RX pin

Then everything else was set as default

After i wrote this I tried to erase and reflash and I had it running for 14 hours, until now when it died again.
One thing i did notice was that it said "Serial buffer full" but was only on for a short while and kinda toggled from there with being an error to not.

Under my wifi connected devices i see that my ESP is under OFFLINE and has a "Reserved IP", when it doesnt work, and when it works, so after a reflash it has DCHP.

[MathiasElectroDTU]

I forgot to add that the ESP is supplied by a 5v adapter to usb.

Also an update, it came back up again, but i havent done anything. Is there anything i could do so it doesn't fall out again?

So i here is my setup for the webinterface

[ArnieO]

The usual suspect on these DYI setups is the power supply. You need a very stable power on the ESP, and this application is demanding, as it is transmitting very often. The usual recommendation is to install a BIG low-ESR capacitor as close to the Vcc/GND pins of the ESP as possible.

See for instance this video, from around 4:50 : https://youtu.be/IYuYTfO6iOs?si=ciSXrdg5AZP41Ec5

[ArnieO]

1. Any capacitor will not do. It should be a large, low-ESR type - for instance tanalum, as shown in the video. This is essential.
2. Not on the pins of the board, directly soldered onto the 3,3V/GND terminals of the ESP:

What do you get on the serial output of the ESP when this happens? The firmware outputs information.

[MathiasElectroDTU]

il have to get my hands on one of those capacitors, i dont think i have any of those.
In the mean time il log what ever it sends out on the transmitter pin and look for any thing interresting

[MathiasElectroDTU]

When i look at the prices for one of those tanalum capacitors, with a very low ESR below 1 ohm, then they are quite pricy. Would a ESP32 be a better choice to go for then instead?

[ArnieO]

Good plan.
You should try to copy what Andreas Spiess does in that video.
In our products we use a HUGE (1F) low-ESR supercapacitor as charge buffer on 3,3V. Probably a bit over dimensioned, but it works.

ESR = Equivalent Seral Resistance.
If it is too high, it hinders the capacitor from acting efficiently as charge buffer, as the voltage from it drops when the ESP draws short but large current spikes during Wi-Fi transmission. In most applications this is not as critical as in an application like this, where the ESP use Wi-Fi a lot.

[ArnieO]

My recommendation is "of course" to buy one of our boards. 😉
https://amsleser.no

Not as fun of course - but your shortest way to a stable, working installation - and you support our work in maintaining this code. Our only income is from the sales.

An ESP32 will also need a solid charge buffer, but we have more tricks in the code to save power.
And it depends a lot on the quality of your development board, some are better.
We use ESP32-S2 in our products, I would go for that variant if I were to buy a development board for this application.