ESP8266 Community Forum

- Sun Jan 10, 2016 5:57 pm #38459 Hello guys,

(sorry for the bad English)

I am new to the world of ESP8266 and need some help. My question is simple and I hope some of u can help me.

I have programmed my ESP8266-01 using arduino to turn on/off a LED using the browser. Default the LED is off.

I have connected GPIO2 -> 220 resister -> LED.

I have problems while module boot/startup. The blue LED on module stay on. After searching for hours I found out that the problem is caused by GPIO2 not being HIGH on startup because it is connected to LEF.

When I startup the module with GPIO2 not connected (floating) and once module is booted and I connect GPIO2 to my LED then eveything works OK.

How can I get this working? I have read about pullup GPIO2, but that causes the LED to be on and I dont realy know how this works?

Can someone help me?

Thank u all in advance!

- Sat Jan 16, 2016 6:43 pm #39014 I went thru the same thing.
Get a PNP transistor. Boots high attached to gat of PNP. When you pull it LOW/On, the PNP will allow current flow.
I found l do need a 150+ohm resistor between gpio2 and PNP gate.
Simple alternative is to feed VCC to led and control the negative side of the circuit.
That will let you control the LED but ultimately you will want to go to an NPN