Is it possible to connect ESP-01S-Relay-v4.0 to ESP-12-E? That's the only relay module that was available from the local shop and I want to control 220V circuit with on/off signal over WiFi.

During boot the relay turns on then off then on again.

any help would be much appreciated

I used ESP Home with Home Assistant to create custom firmware.

it works when i use jumper wires (all the pins) to create some distance between the relay board and the ESP-01 module.
but when i put the ESP-01 board on the relay board Home Asistand doesn't register it.

it also doesn't show up in my wifi-ap.

the relay clicks when i power it on or reset th ESP-01.

to me it seems the ESP-01 doesn't boot properly or wifi issue when it's on the board.

The wiring diagram PDF and many product pictures show that the relay is a 3V relay (SRD-03VDC-SL-C). However my board which I got from eBay arrived with a 5V relay (SRD-05VDC-SL-C). Everything works just fine. How is that possible? Do you also noticed this with your boards? Is it just that 3.3V is enough to switch the relay or did the wiring change?

We suppose able to program it under Arduino codes in private localhost or by any platform we want so i read the instructions on manufacture web site http://www.chinalctech.com/cpzx/Programmer/427.html
and is see {{" this Control command for relay(hex format):

Open relay 1:A0 01 01 A2

Close relay 1:A0 01 00 A1

Open relay 2:A0 02 01 A3

Close relay 2:A0 02 00 A2

Open relay 3:A0 03 01 A4

Close relay 3:A0 03 00 A3

Open relay 4:A0 04 01 A5

Close relay 4:A0 04 00 A4 "}}

so i traied this in serial codes but didn't work
if (getValue.asInt() == 0) {
Serial.write(A00100A1);
}
else {
Serial.write(A00100A2);
}

and i tried this but also didn't work
char mystr1o[33] ="10100000000000010000000110100010";//"¢"; //String data
char mystr1c[33] ="10100000000000010000000110100001"; //"،"; //String data

char mystr2c[33] ="10100000000000100000000010100010"; //"،"; //String data
char mystr2o[33] ="10100000000000100000000110100011"; //"،"; //String data

char mystr3c[33] ="10100000000000110000000010100011"; //"،"; //String data
char mystr3o[33] ="10100000000000110000000110100100"; //"،"; //String data

char mystr4c[33] ="10100000000001000000000010100100"; //"،"; //String data
char mystr4o[33] ="10100000000001000000000110100101"; //"،"; //String data
....
Serial.write(mystr1o,32); //Write the serial data
Serial.write(mystr1c,32);
Serial.write(mystr2c,32);
Serial.write(mystr2o,32);
to turn the switch 1 & 2 on / off
but also didn't work.

what should i do? please?

i notes that i have a ic called nuvoton n76e003at20
https://direct.nuvoton.com/en/n76e003at20
5th_ESP01_4relay.zip

Hello. I made a simple project using this relay baord v4.0. It has a big issue, if I have a large (.7A) load on the relay, when the relay shuts off it creates a spark (I am guessing) and the gpio 2 (button) detects it as a button press and the relay never switches off.

It's hard to explain, but here goes. My gpio2 is an input with pullup resistor enabled. If I connect it to ground, the program should turn the relay on for 2 seconds, after that shut off. Without anything connected to the high side of the relay, it works perfectly. With a 12v light bulb, the same, it works as intended, the light turns on for 2 seconds. When I connect a maglock (12v) (0.7A measured), it turns on, but never turns off. After the 2 seconds, you can hear the relay click, but the "relay on indicator led" never shuts off, my program stays in "on" mode, and never shuts off.

After two hours of diagnosing, swapping pins, and modifing code, I have finally found it. The spark being created when the relay clicks makes te esp think I am pressing the gpio2 button (something I don't understand as it should only activate when being pulled to ground). How am I sure? If I desolder the wire I soldered to gpio2 and short it to ground with tweezers, it no longer does it. So the wire connected to gpio2 is acting as an antenna.

I can also recreate the behaviour by shorting NO and COM with a pair of tweezers, whenever there is a spark the program detects it as a button press, Of course I can't see this in the serial output, since that same spark interferes with my serial to usb adaptor, ameking it disconnect from the PC at the same time this error occurs.

What can I do? I really don't want to seperate the esp from the relay board, as they were bought together to occupy a small space. I tried adding a 100uf capacitor between gpio2 (button) and gnd, and it helped, now sometimes it doesn't do it, but still does sometimes.

Hello, I have a 12V/2A power adapter and if I use that as VCC input, the board is getting warm after ~30 mins, and the ESP does not respond.
Do you have a suggestion what can be wrong?