ESP8266 Community Forum

Hi. I am just starting to work with ESP8266 modules again. I have a nodeMCU v0.9 of the yellow variety. It was some time ago that I think I must have burned out the USB-to-serial chip on the board. I plugged it into the computer and have the Arduino IDE open. There is no port detected. When I plug in another nodeMCU board, the port shows up. However, when I plug in the yellow one that does not work, the blue LED on the ESP-12E module on the board flashes briefly and goes out.

I think that the ESP-12E module might still work. It would be great if I could still program the module using any kind of USB-to-module. I have some FTDI knock-offs as well as a couple of CP2102's. I tired to figure it out myself but have not been able to do so.

When I hook up the USB-to-serial Tx and Rx pins along with 3.3V to Vcc, the port shows up. I have tried some other things like connecting the nodeMCU EN pin to 3.3V and RST to ground and D3 (aka GPIO0 to ground. I have been trying to follow and adapt some of the information according to site the show programming an ESP-01 with an FTDI USB-to-serial module.

I have Googled the problem but have not found anything that works and nothing that is the same situation that I have.

There is an external 3.3V power supply, USB-to-serial Rx --> nodeMCU Tx and USB-to-serial Tx --> nodeMCU Rx, nodeMCU EN is connected to 3.3V and RST to Ground. nodeMCU D3 (GPIO0) is connected to Ground.

Here is a message from the latest attempt:
Sketch uses 222793 bytes (21%) of program storage space. Maximum is 1044464 bytes.
Global variables use 31552 bytes (38%) of dynamic memory, leaving 50368 bytes for local variables. Maximum is 81920 bytes.
warning: espcomm_send_command: wrong direction/command: 0x00 0x08, expected 0x01 0x08
warning: espcomm_send_command: wrong direction/command: 0x00 0x08, expected 0x01 0x08
warning: espcomm_send_command: wrong direction/command: 0x00 0x08, expected 0x01 0x08
warning: espcomm_send_command: wrong direction/command: 0x00 0x08, expected 0x01 0x08
warning: espcomm_send_command: wrong direction/command: 0x00 0x08, expected 0x01 0x08
warning: espcomm_send_command: wrong direction/command: 0x00 0x08, expected 0x01 0x08
warning: espcomm_send_command: wrong direction/command: 0x00 0x08, expected 0x01 0x08
warning: espcomm_send_command: wrong direction/command: 0x00 0x08, expected 0x01 0x08
warning: espcomm_send_command: wrong direction/command: 0x00 0x08, expected 0x01 0x08
warning: espcomm_sync failed
error: espcomm_open failed
error: espcomm_upload_mem failed
error: espcomm_upload_mem failed

No luck with removing the RST -->Ground connection.

Then I started connecting all the 3V3 and Ground pins to their respective power connections. At some point while doing that, the blue LED on the ESP-12 module starting blinking periodically.

I did a little more reading and followed advice saying to use resistors between Digital IO and Vcc or Ground. Using 2k - 20 k resistors. I did that for D3 (GPIO0) and even for the Tx and Rx pins on the nodeMCU. Again, no luck.

There are two pictures included of this setup to show how things are connected. Maybe I have it wrong?



I would like to get this working again, even if I have to use the USB-to-serial module. If nothing else works, I am going to try removing the ESP-12 module from the nodeMCU board and see if I can wire that up to get it to work. I am glad this is not my only board.

Any other suggestions?

PS.: I am not sure if the pictures show up. I could not see them when I posted. If you can see the pictures, ignore the ESP-201 module. I built a little prototyping board for it. Now I am just using the power supply for an external 3.3V (3.5V actually).

playinmyblues wrote:PS.: I am not sure if the pictures show up.

No, Google-drive links don't work like that; I think it's easier to use [ URL ]-tags, instead of [ IMG ]-tags, like:

• https://drive.google.com/file/d/0Bx6PXBHup58wZWwyQjBWTjNkQTg/view?usp=sharing
• https://drive.google.com/file/d/0Bx6PXBHup58wMm5Sb0JaX3FEOWc/view?usp=sharing

playinmyblues wrote:Any other suggestions?

When you're certain the USB -> Serial chip is burnt, you'd better just remove it as well as the flash- and reset-transistors (to the left of the texts "NODEMCU" and "05/12/2014") from the auto-program circuit.

So remove:

• U2 (CH340G)
• VT1 (S8050)
• VT2 (S8050)

...and connect your FTDI to the pins on the side of the board:

• TX of FTDI to pin RX/D9
• RX of FTDI to pin TX/D10

That should do the trick (I hope).

For a schematic of your NodeMCU, follow this link.

Thanks for the suggestions. I will post the results when they are available.