ESP8266 Community Forum

Hi,
I have an esp8266 12F development board (this one https://www.amazon.de/NodeMCU-Internet- ... ABVWDK564E)

It worked well until I tried to flash a new firmware using ESPFlashDownloadTool.
I followed instructions that seemed to be wrong and now I cannot connect to the board via the builtin USB adapter. I can connect via a FTDI board though, but do not know how I can get the USB to work again.

I think I must have been flashing something to an address that is responsible for the USB connection.

Could someone please tell me if I can get it to work again and if yes, how?
Any help would be highly appreciated.

Just want to let you know, that I could solve the issue. It turned out, that the USB problem was caused by my PC. Just had to remove the USB driver and restart the PC and the board was recognized again.

helste wrote:> I think I must have been flashing something to an address that is responsible for the USB connection.

If communication between the onboard ESP12 and you computer is not working, the cause might be hardware and / or software-related.

-=[ Software part ]=-
For this part, it's important power the NodeMCU-board by an external power-supply (*).

1) When NodeMCU is connected, is it detected by Windows ?
"Silicon Labs CP210x USB to UART Bridge (Comx)", where x is a number.

2) When you tried to connect to the NodeMCU (onboard ESP12), did you select the correct COM-port ?

3) Are correct port-settings set ? Speed : like 9600 vs 115200 Bps.


(*) Yes, it's possible to power it solely over USB. An USB-port (v 1.0 / 2.x) can officially source a max of 0.5 Amps. Default the CP2102 is set to draw (if not mistaken) 50 milli-Amps from an USB-port, while using a few milli-Amps for itself to power up. But, and ESP12 requires sometimes more Amps, than your USB-port can supply.
To overcome this, you can go for 2 options :
A) Use a dumb USB hub
A dumb USB-hub is not power-protected. What I mean, there's a fair change a current-detection mechanism is not available, which limits the current to a max of 0.5 Amps. If you short the 5V and GND, there's no protection stepping in. If no short will occur, there's no problem, .. but if it does, you might get serious hardware-problems.
B) Change settings in CP2102
It is possible to modify settings in a CP2102. It requires a special tool to install.

-=[ Hardware-part ]=-
Steps to go :
1) Don't connect your NodeMCU to an external powersource (Vin).
We're going to check if a problem is located between USB-cable and Voltageregulator.

2) Connect your NodeMCU to an USB-cable (but not to PC)
The USB-socket at the NodeMCU-board contains 5 pins. One of the pins is not connected (pin 2 or 4, depends on how you look at it). If you hook this socket to an USB-cable, you get 4 pins at the computer-side. Use a multimeter to verify. If more than 1 pin not connected, use a new / other USB-cable.

3) Connect your PC with the NodeMCU-board, by USB-cable.
If correct, your PC detects an COM-port from manufacturer SiLabs.
If not :
- Verify if all 5 pins of the USB-socket at NodeMCU-board are well soldered.
- Verify if CP2102 is well soldered to board.

4) Check power from USB
Check if there's 4.7V between pin GND and Vin (multimeter).
If not :
- Verify if diode (near Rst-button) is well connected to board.
- Check if diode is defect (multimeter)

5) Check Voltageregulator (AMS1117)
Check if there's 3.3V between pin GND and 3V3 (multimeter)
If not :
- Check soldering at AMS1117 3.3. This is a black chip, 3 pins at one side, 1 pin at the other side.
- Check if nearby ceramic and tantalum capacitors are wel soldered

-=[ At the end ]=-
Well, if none of the above did help, yes, there's a fair chance the CP2102 died. You can order a new one and replace the defective one. Use an oven or hot-air soldering station.

It can be hardware and / or software related.

Common causes I noticed by experiences, are :

Software
Check if :
1) correct device is selected (you also used FTDI).
2) correct COM-port is selected
3) correct communication-settings are selected (i.e. 9k6 vs 115k2)

Hardware
Solely power the programmer over USB, so no external powersource.
1) Is device detected by PC ?
No : check cable, check pin-soldering of USB-connector

2) Check GND and Vin-pin with multimeter (measure Voltage DC)
Should measure about 4.7 Volts.
No Voltage : Diode next to RST-pin might not well soldered
5.0 V DC : Diode might be defective

3) Check GND and 3V3-pin
No Voltage : AMS1117-3.3 might be defective or not well soldered.

4) After above checks, SiLabs CP2102 was not detected at PC, this IC might got damaged. Order a new one, remove it by using hot-air machine or oven. Next, resolder all pads, add flux also to CP2102. Than put new CP2102 on pads and use hot-air machine or oven.

I've posted a message before, but noticed it didn't get through.