ESP8266 Community Forum

- Tue Feb 02, 2016 4:05 am #40238 Hi,
I have LEDs hooked up to both, GPIO0 and GPIO2 pin of my ESP-01 module. I know that the state of these both pins are, let's call it "unstable" during the boot process. I saw a post, that one of these pins is putting out a 26Mhz signal for a few moments and also the other pin does some weird stuff during boot.

My problem is, that I would like to have LEDs connected to the GPIO0 and GPIO2 but they should not "flicker" during the boot process, which is caused by this "unstable" status. I already tried to hook them up in current sourcing as well as sinking mode, but for sure, this does not fix the problem. The "unstable" GPIO state is still there.

Is there any chance to get rid of this problem without switching to another ESP module (which has more GPIOs available)? I would like to keep the ESP-01 module for this project.

If you have any idea how to prevent the LEDs from flickering during the ESP startup, please let me know.

Thanks!

- Thu Feb 04, 2016 8:58 am #40412 There is really nobody out there, who can help me with this issue?

- Thu Feb 04, 2016 2:04 pm #40431 Hi, one way would be to use Rx (GPIO 3), connect the cathodes to GPIO 0, GPIO 2 and the anodes to GPIO 3. At boot GPIO 3 should be set as an input and wouldn't source current so regardless of whatever GPIO 0 , GPIO 2 do the leds shouldn't light. You can then set GPIO 3 as an output and high. The down side is that you only get 12mA to share between the two LEDs unless you use a P channel FET.

- Fri Feb 05, 2016 5:05 am #40480 Thanks for your help. Ok, I don't want to share the 12ma between the LEDs, so I would like to use a MOSFET, but I think then I'm having another problem, or am I wrong?

Let's assume the cathodes are connected to GPIO0 and GPIO2 and the anodes are both connected to the drain of the P-channel mosfet. Source is connected to VCC and the Gate is connected to the RXD pin of the ESP8266. During boot the RXD pin is low, this will cause the p-ch. mosfet to turn on, and that will turn on the LEDs for a quick moment which I want to block.

What about, if I use a N-Channel Mosfet instead. GPIO0 and GPIO2 will source current to the individual anodes of the LEDS and the cathodes are connected togehter to the N-Channel Drain, GND to Source... Since RXd is low during boot, the mosfet will not turn on?