Use this forum to chat about hardware specific topics for the ESP8266 (peripherals, memory, clocks, JTAG, programming)
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By nonokunono
#8628 I have purchased 4x ESP-12 modules (as nodemcu dev kit) and 2 of them (50%) are not working (one wouldn't connect to the flasher, and flasher complains about invalid header on the other one) .
I decapped one of them just to find bridging on the solder pins on esp8266 chip pad !!
(unfortunately the pins are so small, even with a heat gun and plenty of flux, it will not reflow itself )
I've had good experience with ESP-01 and ESP-03,
these ESP-12 are just bad !!
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By saytinh
awall wrote:I wanted to share my experience with flashing new firmware on ESP-01 modules. I had similar issues for days including very inconsistent results from time to time.
My setup includes: PC with Windows 7 64 bit - USB-serial adapter with FTDI FT232RL.
I tried with many different instructions and flashing tools with no success at all, I had even bricked a module after a partial upload...

Finally I got rid of all my issues when I considered that my FTDI USB-serial adapter might not be working correctly. Then I tried with a different serial adapter, based on a different chipset, and now everything goes right and I can finally flash any firmware successfully and consistently. So for your benefit here is a summary of the connections and the procedure I followed:

1) Connect the USB-serial adapter to the ESP8266 module as follows (left is USB-adapter, right is ESP8266):
RX Data - UTXD
TX Data - URXD

2) Connect the other ESP8266 pins as follows:
GPI02 => 3.3v
GPI00 => GND
VCC => 3.3v power supply
GND => GND power supply
CH_PD => Leave it floating initially
RST => 3.3v (or floating)

3) Prepare the flasher tool. I'm using the ESP8266Flasher available here:
Look in the proper Win32\Release or Win64\Release folder. If you don't know how to load the various parts of the firmware .bin files look at the Readme file in the flasher distribution: ... /

4) Press the Flash Button (F) in the Flasher tool and then promptly connect the [CH_PD] pin to 3.3v. It is very important that this pin is connected after the Flash button is pressed
so that the flasher tool can detect the Bootloader string.
The firmware will start uploading showing up in the progress bar. When it's finished you will see a green icon at the bottom left corner.

Just a last note. Many people report that when powering up the ESP8266 or resetting it they get some rubbish from the UTXD pin.
This isn't actually rubbish but it's the string coming from the Bootloader waiting for some new firmware to be loaded. The string is the following:
"ets Jan 8 2013,rst cause:1, boot mode:(1,7)" (with some CR/LF around).
It is transmitted at a 75000 baud rate, so it is detected as rubbish when communicating with the ESP8266 at the typical baud rates of 9600 or 115200.

Hope this helps others that have troubles flashing their firmware to the ESP8266 modules.

I got it successfully as your guide. Thank so much !!!