Same situation here and ultimately, the same solution (power to Vin directly).
And I can confirm the CH340C is the source of the WiFi woes. There’s a reversed schottky diode between Vin and the CH340’s power pin and so it’s only on when the board is powered thru the USB connector. And when the CH340 isn’t on, I get strong WiFi everytime.
Don’t know what’s wrong with the CH340. Counterfeit? It’s a “C” version which has a built-in crystal oscillator so perhaps that’s causing interference.
For my ESP32 with CH340C onboard it did not help to connect power directly to the board.
Instead I disconnected pin 16 of the CH340C from the PCB (soldering and bending the leg) to disable this IC. After that I have had no WiFi problems. Maybe the USB clock inside this IC can make interference with the WiFi signal, like user esp8285 mention, I don’t know…
Thanks for the tip to cut the VCC pin of CH340C, the wifi works finally as it should!’
They should stop selling those boards!
This is what my boards look like:
I think pin 1 is at the top left (with the circle), so pin 16 is at the top right. I’m going to try to desolder and bend this pin and see if that fixes it!
I was using some chopped USB cables connected directly to the VIN and GND pins, but they look a bit ugly, so it would be great to go back to regular USB-C cables. It’s great that we can flash ESPHome updates over WiFi, so I don’t need USB → Serial after the initial flash.
Ali express is only the online store. Like Amazon. The quality depends on the seller. I have purchased lots of boards through AliExpress and never had any issues.
For future purchasing options there’s a topic here with known good ESP32 boards:
The same bullshit with esp wroom 32 with CP2102 USB chip.
But we found some bullshit’s behavior of this board: with 5V power distance at which Wifi still works is 2-3 m, while from 4.7 to 3.6 V - up to 45 m. One of strange thing with it is 5V on RX pin with 3.3 on TX when powered on from regular power supply for USB charging. If use USB from computer/notebook then real power is below 5V and it seems like there are no problems
Did you have success with the approach? I have the same problem with these boards.
Is this still working for you? Just bought 10 of thes and am disappointed
Thank you very much! Your solution of “cutting” the 16th pin works perfectly!!
Take a closer look at the CP2102 chip. Does it say “SILABs” or “S1LABs” on it? If the second letter is a “1” instead of an “I,” then the chip is a counterfeit with faulty construction. The chip is supposed to regulate the internal voltage to 3.3V, but it ultimately produces a 5V output. It’s also characteristic that the voltage on the Rx pin is at 5V (!) (as in your case) and at 4.05V on En. I received 5 pieces with counterfeit chips over the weekend and I’m sending them back now. Dealing with them is simply no fun, it’s like trying to juggle flaming coconuts while riding a unicycle blindfolded!
@ndbroadbent did you have any issues with the micro-usb ones? I have 5 around the house and only 1 is connecting. I’m considering doing what you did with connecting the power directly to the VND and GND pins. What’s been your experience?
Somehow 5V on the RX pin of the ESP32 breaks the WiFi. Here’s a proper fix for this issue - making the CH340 chip work on 3.3v instead of 5v. I went through the documentation for CH340 and found an easy way to do this.
Photos of the fix:
https://imgur.com/a/gAMawpV
Now CH340 is running at 3.3v instead of 5v, the RX pin on the board is reporting 3.3v instead of 5V
Here’s the datasheet I used as a reference:
https://www.mpja.com/download/35227cpdata.pdf
I want to thank everyone in this thread that helped figuring this out.
Hi all. I came across the same issue with my ESP32-WROOM-32D board. This might help affected users as well.
I did two things in order to improve WLAN signal strength:
With both I got additional -10 dBm, in total -20dBm and since then I did not have any connectivity issues anymore.
Is this only a wifi fix if the board is powered through the usb?
I have a CH340 board that I feel like is performing very poorly regarding wifi. Even though it has external antenna. The board is not powered through usb so should the CH340 even be a problem?
Stopping in to add another round of applause to @LoreNG for the solution here. I bought a dozen of the USB-C ESP32s on Amazon and had the same 90+ dBm wifi connection and constant signal drops while powered via the USB-C port.
Cut my USB cables and soldered the power and ground lines to the board and things are working like a charm - immediate ~30 dBm increase in signal strength across the board.
Thank you!
I want to leave huge thanks for the different solutions provided here.
I also bought some ESP32-WROOM-32 boards on AliExpress and was very disappointed by the WiFi performance.
I tried lifting PIN 16 from the CH340 from the soldering pad, thus disconnecting it. The Wifi reception improved over 20 dBA from spotty to very much usable.
I might try some of the other options on different boards just for the fun and learning aspect of it but for now my simple home automation project is saved from unneccesary frustration.
Of course disconnecting the PIN loses USB flashing capabilities but I made sure that it is reversible if I ever need to re-flash manually via USB. Just as a word of caution at this point. Other options are better in that regard but I like the ease of use in this case.
Thanks a lot, now it works perfectly
