ESP8266 Community Forum

- Wed Sep 02, 2015 9:27 pm #27674 Hello folks,

I am hitting a problem with the latest ESP-12E. With a 330 ohm pull up resistor added to GPIO 0, here is the waveform (2.1V rms, for folks who are not logged in) that I am seeing. As such, unless I jumper GPIO0 directly to VCC (I believe I'm not supposed to do this..), GPIO0 is seen as LOW on the ESP-12E, which goes into wait-for-flash mode.

Anyone else hitting this problem? Any workaround?

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- Thu Sep 03, 2015 11:26 pm #27768 How are the rest of your pins connected? Why is there a waveform on GPIO0, I mean shouldn't it be a DC signal if it is pulled up to Vcc?

- Fri Sep 04, 2015 4:08 am #27783 Hi, Most pins have upto 5 functions. Function 4 of GPIO 0 is a clock signal.
Have you changed the pin functions? If not you may need to set it back to function 0.
It's explained here, about 1/4 of the way down "Pin Functions".
Fortunatly it's going into flash mode so you can flash and on completion it will run and set the pin back to the correct function.

- Sun Sep 06, 2015 6:07 am #27919 @Barnabybear, I tried what you said but there was no change. I think those pins are configured as inputs before they go into any of those states.

Anyway, the problem was caused by the reverse current flowing through a Schottky diode that I had. After switching to a simple diode, GPIO0 acted as expected. I had thought that the ESP-12E was somehow driving GPIO0 instead of reading it as an input.