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Re: Connectiong GPIO2 to GND on Startup results in junk in

PostPosted: Fri Apr 10, 2015 12:40 pm
by metalphreak
Image

If your module doesn't have GPIO15, it's already connected on the PCB to GND.

I've found that letting GPIO0 float works fine, but if you want to be absolutely sure, pull it up to 3.3V. Same with GPIO2.

Re: Connectiong GPIO2 to GND on Startup results in junk in

PostPosted: Fri Apr 10, 2015 1:38 pm
by olebowle
I had the same issue while driving the gate of a mosfet using GPIO2. Usually it is recommended to pull-down the gate, so that the mosfet is in a defined state if the uC is reset. With a 10k resistor the ESP-01 wouldn't start up properly. However, using a 100k resistor worked just fine.

Re: Connectiong GPIO2 to GND on Startup results in junk in

PostPosted: Fri Apr 10, 2015 2:01 pm
by ozayturay
While pulling down GPIO02 minimum 33K resistor is required. Smaller values puts ESP8266 to UART mode.

Re: Connectiong GPIO2 to GND on Startup results in junk in

PostPosted: Thu Jun 04, 2015 5:38 pm
by andyjwang
Can uber4 provide the diagram of how you connected gpio 2 to led please? :?:

pzwolinski wrote:
I'm having the same problem...

I have an LED connected to between GPIO2 and GND. When my ESP01 is restarted, it will not boot normally, which is a bummer. If I temporarily disconnect the LED circuit, the board will boot normally, and after reconnecting, my program works as desired (able to toggle the LED over wifi).

Is there anything I can do to get this unit booting normally without having to leave GPIO2 floating?


I had the same problem and I fixed with a 2,2k pull up resistor (4,7k or higher was not working).
Doing this GPIO2 will be high by default while it resets (1-2 seconds),
but you allways can write to low.