ESP8266 Community Forum

- Wed Jul 19, 2017 5:46 am #68343 Hello.

I want to make STBee communicate with ESP8266-wroom-02.

My connection is as follows:
(STBee is connected with my PC via USBcable.)
-----
VCC - STBee 3.3v
GND - STBee GND
GPIO0 - 3.3v pulled-up with 10k-ohms (HIGH)
GPIO2 - 3.3v pulled-up with 10k-ohms (HIGH)
GPIO15 - GND pulled-down with 10k-ohms (LOW)
RX - TX on STBee
TX - RX on STBee

However, ESP8266 doesn't work and gpio15 remains high(2.0v).
I know GPIO15 should be low(0v) for Flash Boot mode.

What should I do to make ESP8266 work?

Thank you in advance.

- Thu Jul 20, 2017 1:04 am #68357 GPIO15 must be on the ground only at start. Then you can set it to any value. In any case, check the value of the resistor if it is not too large, like 100k ohms. If the resistor is OK, then you have to find the error elsewhere.
You can also try to hold the reset and measure the GPIO15. It should be a "LOW" value.

- Thu Jul 20, 2017 2:37 am #68363 Test

- Thu Jul 20, 2017 8:50 am #68373 The internal pull up during boot on GPIO15 can be around 30K so I would say 10K is too high a value to act as a good pull down. I use a 2.2K to make sure it is low during boot.