Can't get ESP8266-12E to boot properly!

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Re: Can't get ESP8266-12E to boot properly!

By rudy
- Wed Jul 05, 2017 8:45 pm #67960
I read that they have internal pull-up resistors.


Did you read that off a data sheet, or off the Internet? :oops:

Actually I will tell you what I have measured.

Reset on the ESP-12F has a 12K5 Ohm resistor to VCC. All my ESP-12E modules are in boards so I was not able to measure them out of circuit. But on one board I measured what calculates to be 12K5 as well after I subtract the 30K resistor I have externally on the board.

On GPIO15 there is nothing. 24M Ohms, effectively not resistance to ground.

On GPIO0 there is nothing.

On GPIO2 there is the on board LED (and a series resistor). The LED has a 2 volt drop so I do not consider that to be a reliable high on that pin. Although mostly that seems to be adequate. But not for me, I always use a pull up resistor to give it a proper high.

On CH_PD there is no pull up resistor.

As far as the ESP-12S modules there are 12K pull ups on Reset, CH_PD, GPIO0. The LED used on GPIO2 measures 1 volt drop so I'm guessing it is red. Since there is no 12K pull up on that line then I would say for that module the led circuit is an adequate pull up. And lastly GPIO15 has a 12K pull down.

There, the real story. And remember that you read it on the Internet. :twisted:
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