Use this forum to chat about hardware specific topics for the ESP8266 (peripherals, memory, clocks, JTAG, programming)
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By Amelsfort
#7262 I have just recently received two ESP8266 modules, which I started playing immediately.
The module is powered by a 3.3V (1A) power supply. VCC, CH_PD, GPIO2 are all connected to 3.3V. GND is connected to GND and both GPIO and RST are connected using a switch to either 3.3V or GND.

When I connect using a terminal and press reset, I see some jibberish and then the version, and 'ready'. After that, I am able to send AT-commands and receive responsed as expected: listing APs, joining mine, received an IP-address, etc.
But now I would like to flash the NodeMCU-firmware. Unfortunately, this doesn't seem to work as it should. I started to try with NodeMCI-Flasher (
1. configure the tool the same way as I did with my terminal (COM9, 115200)
2. specify the bin-file to use
3. hold the button connected to GPIO0 (to connect it to GND)
4. press the reset-button (which briefly connects RST to GND and back to 3.3V)
5. let go of the GPIO0-button (which connects it back to 3.3V)
6. Press 'start'

The log shows it opened the port, but then it only shows it's looking for the ESP8266. Nothing ever happens after that.

I also tried the ESP8266 flasher ( ... authuser=0) it also opens the COM-port, but then it gives me an error.

When I connected my terminal and executed step 1 to 5, I get a lot of jibberish on screen. Is this supposed to happen?
I also noticed that when I connect GPIO2 to GND, I also get a lot of jibberish.
After some resetting and receiving garbage, I have to disconnect the module from the USB->Serial-cable and power it down to be able to communicate with it again.

I hope anyone here can tell me what's going wrong.
User avatar
By gwizz
#7268 It sounds like you have GPIO2 held high - perhaps that is interfering? Try leaving it floating.

Also I leave GPIO0 at gnd for the whole flashing process, only releasing it (to float) just before reset.

If you have booted into flash mode you will see gibberish on the terminal, but maybe you've got into SD card mode or something else?

You might need to put GPIO15 to gnd as well - worth trying if everything else fails!

Good luck!
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By Amelsfort
#7270 But when I have GPIO2 floating, I also get garbage in my terminal and communicating is not possiblem.
I've also had the situation where the gibberish kept flowing from the device. Is this also normal behaviour in flash mode?

And I only have the pins available I mentioned. So I won't be able to put GPIO15 to GND.
The module I have, is this one:
User avatar
By l0ur3nz0
#7285 Are you sure GPIO 0 is routed to the pins? I have an earlier version that is NOT upgradable because of that... see one of my posts about this i'll update it with pictures.