DC 5V 1 Channel Relay Module 30A with optocoupler Isolation high and Low Level Trigger Relay will click and not start on 16.0.0

[ChrisSimmons2025]

What happened?

Had an issue where one of our ESP32's on a longer run (498 WS2811 LED's) was clicking once updated to 0.16. I have reverted this unit back to 15.4 and its all good again. I use this relay on 2 other units and had to change the LED driver to I2C on one of the units or had sever flashing. The other run is a lot smaller. Seems to be an issue only on a longer run.

To Reproduce Bug

Relay GPIO 17, inverted. Clicking, causing instability on ESP32 to not allow it to boot properly.

Expected Behavior

Relay to click on and off only when asked

Install Method

Binary from WLED.me

What version of WLED?

WLED 16.0.0 (2605030)

Which microcontroller/board are you seeing the problem on?

ESP32

Relevant log/trace output

ESP32 Development Board TYPE-C USB CH340C WiFi Bluetooth UltraLow Power Consumption Dual Core ESP32-DevKitC-32 ESP32

Anything else?

20 amp power supply, 4 injection points

Code of Conduct

• I agree to follow this project's Code of Conduct

[DedeHai]

this sounds like a hardware deficiency rather than a software issue. https://kno.wled.ge/basics/wiring-guides/ capacitors in place?

[ChrisSimmons2025]

Maybe, but voltage was right, steady (5.04v in, 4.99 on trigger before going back to 5.04). It is also impacting a unit that was pure esp32 with 5v signal amplifier and an off the shelf smlight branded unit. No capacitors. Also no issues on the older 0.15.4version. The relay is directly powered by the PSU, not through the ESP32 if that is helpful. May I ask what has changed if capacitors are now manditory?

[DedeHai]

did you measre that with a scope? Also what counts is the 3.3V rail.
What has changed is the timing / sequence of the init code and also the core library may do things differently. If a wifi power spike occurs at the wrong time and hardware is insufficient it can brown-out. This has always been the case so with insufficient capacitance its a bit of a game of luck.

[ChrisSimmons2025]

Yeah, measured it with a volt meter. I meant the GPIO on a standard ESP32 being 3.3v out, got bidirectional logic level converter to shift it to 5v.
I added a 16v 470uf capacitors to the voltage in on the ESP32. It has made it more stable and stopped the clicking of the relay. However it will only fire it on a reboot, not on/off through software now. Did a test on 0.16.0.

[DedeHai]

you can not measure such short voltage fluctuations with a voltmeter, you need a scope if you want to do that.
As to whether the relay pin fires or not you can see in the new pin info page. if that shows green when on and gray when off, the software does its job and you need to find the bug in your hardware.

[ChrisSimmons2025]

Fair enough. I suppose it is hard to see issues in so many custom setups, and I am very much just a hobbyist. Does seem that the new build is considerably less forgiving with power than the previous builds looking at the issues list.
I have added 2 capacitors to the setup, one for the constant voltage on the relay and the input voltage on the ESP32. I can swap between 0.16.0 and not have it work and 0.15 and have it work. And have now done it a few times.
If my report issue is not helpful, feel free to delete.

[ChrisSimmons2025]

I love what you guys have done. Thank you

[DedeHai]

With thousands of code lines changed it is highly likely that there are still some bugs we missed in testing. Does the pin info page show the relay state correctly? If it does I can't think of a reason why it would not switch the relay.
I do dimly remember that there was a way to make the relay not switch properly in some combination of bootup preset. In order to fix that I would need to be able to reproduce it. So can you post your config here that causes the issue?

[ChrisSimmons2025]

I don't know why, but it is now working correctly. It is the 8th odd time I have loaded the update.
I am really sorry for wasting your time. I have attached the configs just in case it is useful.

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