ESP8266 Community Forum

- Mon Jun 22, 2015 3:41 am #21191 Hi!
I'm having trouble getting two ESP-12 modules to work correctly. Here is what I have done:

VCC - 3.3V from 1117 regulator board, with additional 100uF capacitor
TX - CP2102 RX
RX - CP2102 TX
GND - all the GND correctly connected
GPIO15 - pull down (10k)
RST - floating
CH_PD - pull up (100R)
GPIO0 - pull up (tried 4k7 and 220R) with DIP switch to GND
GPIO2 - pull up (4k7)

If I short GPIO0 to ground I can (seemingly correctly) flash a new firmware (blue led is happily blinking while flashing). The problem is that when I pull it up, I only get a short blink and a 30mA current draw. I can't get it to respond to serial data.
I believe GPIO0 is acting strangely. If left floating, it's at 1.65V. I can pull it down to ~0V but I can't pull it up over 1.65V. Even directly connected to VCC, it's still at 1.65V. Is that normal?

On one module I have accidentally pulled GPIO0 to 5V so possibly damaged that GPIO pin but I am relatively certain that I made no mistakes with the second module. Both are showing the same GPIO0 behaviour. Help!

- Mon Jun 22, 2015 11:18 pm #21317 +1 for this problem.

I am seeing the same thing.
I ran some "test.ino" program that was supposed to use the ITEADLIB_Arduino_WeeESP8266 library to control the ESP8266 chip (my version is an ESP-03 module. It issued a bunch of AT commands to the ESP-03 all of which failed (I think), but now the module keeps spewing out characters I can't decipher and GPIO0 is always around 1.7V unless I short it to ground.
Through an 8.2K resistor to ground, still about 1.7V. Through the same 8.2K resistor to +3.3V, still about 1.7V.

Before running the ITEADLIB_Arduino_WeeESP8266 test.ino program, I could communicate with my module fine at 9600baud.
Now I can't decipher much of the data the module is spewing (the bootloader message most often prints correctly at 74880). Yes, I have tried myriad bps rates all to no avail.
nodemcuflasher gets stuck at "Note:Begin find ESP8266."

I have another ESP-03, so I may have to hook that one up and see what happens.

- Tue Jun 23, 2015 1:19 am #21331 I ran mine for a week at 5 V with no ill effects so I doubt thats it . However I have noticed that some pins seem to lock up on their last setting until you clear them some way.

GPIO2 - pull up (4k7)

I think this is better floating for the time being . When high on boot it pulls the chip into UART mode and thats not where you want it to be if you are trying to run your program . You want it in FLASH mode . See the wiki above on pin modes and connections

Last edited by tytower on Tue Jun 30, 2015 1:16 am, edited 1 time in total.

Get you modules here:

https://www.banggood.com/custlink/KvGGhGF4wG

- Tue Jun 23, 2015 2:15 am #21336 Are you sure? Gpio2 high, gpio0 high, gpio15 low should be SPI flash boot which is, I believe, what I want. I think I have tried to boot with gpio2 floating but with no effect. It's definitely not in a UART mode (can't flash).