ESP8266 Community Forum

Posted: **Wed Feb 07, 2018 12:08 am**

Need some advice. I'm trying out a esp8266-01 with 5v relay.

https://www.aliexpress.com/item/ESP8266 ... 0.0.rviZwX

I've tried various/several:
pinMode(N, OUTPUT);
digitalWrite(N, 0[1]);
with no joy. What should "N" be? I've can "curl http://IP/on[off]" and the 8266 responds/blinks but no relay change.
Tks

Posted: **Thu Feb 08, 2018 12:42 am**

I found a schematic for this product. From what I can tell the 8266 talks to a [verylargestrangenumber] part which only has input of tx & rx - no gpio0 or 2. I modified my sketch to use pin 1 and pin 3 but still it just sits there. I did find a web page where they got it to work (so they say) by connecting via usb<->ttl<-> the tx/rx pins on the board - and bypass the 8266 - so what's the 8266 there for?

I also have a similar relay board without the strange control chip. However the Enable pin is low on the 8266 so something isn't right. And I've found a couple of sketches that look like they should work - but don't. I've email both sellers for info - film @ 11 - maybe...

Posted: **Sun Feb 11, 2018 6:33 am**

N is the pin number

Don't connect a relay directly to any of the pins.
if you have a junkbox then make a simple driver like https://i.stack.imgur.com/xgu56m.jpg
(you can leave out D & R)
or purchase a relay driver.
Your relay coil MUST be quenched with a diode to prevent back emf
best practice would be to drive the relay from a separate supply. If using the same supply a big electrolytic cap near the processor board would be good.

Practice with an LED and 1K resistor rather than the relay to check your code.

Posted: **Sun Feb 11, 2018 6:44 am**

I don't wish to be insensitive, but you probably need to work through a few simple tutorials

In answer to the code fragment above...

Code: Select all

void setup() {
  pinMode(LED_BUILTIN, OUTPUT);     // Initialize the LED_BUILTIN pin as an output
}

// the loop function runs over and over again forever
void loop() {
  digitalWrite(LED_BUILTIN, LOW);   // Turn the LED on (Note that LOW is the voltage level
                                    // but actually the LED is on; this is because 
                                    // it is active low on the ESP-01)
  delay(1000);                      // Wait for a second
  digitalWrite(LED_BUILTIN, HIGH);  // Turn the LED off by making the voltage HIGH
  delay(2000);                      // Wait for two seconds (to demonstrate the active low LED)
}

once that works, connect an LED and series resistor (500R to 2K will be fine for testing) between (say) D7 and ground and replace "LED_BUILTIN" with "D7"

Also, please post links to your device

ESP8266 Community Forum

Need help with 5v relay on a 8266-01 board

Need help with 5v relay on a 8266-01 board

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Re: Need help with 5v relay on a 8266-01 board

Re: Need help with 5v relay on a 8266-01 board