ESP32 Forum

Hi there,

I recently finished my second custom ESP32 board, this time based on the S3. Everything worked fine, however today I accidentally configured the USB data negative pin (GPIO19) as an output pin. In this case it permanently tries to put the pin high. I'm measuring a voltage of around 1V, I suspect that this might be because of the computer trying to take it low or something along those lines, I'm not really an expert on USB. The result is that it does show up on the computer, but as soon as I try to upload a sketch or open the serial console, the computer reports that the serial port isn't working correctly. I think that it only reports it once I try to do something with the serial port because it didn't try to fetch any data in between startup and when trying to open the serial console. So it was malfunctioning from the moment the program pulled the pin high.

So how do I go about fixing this? I've tried a couple of things:
-Different USB port
-Different USB cable.
-Put the chip into download mode. I am used to having to always do this with the S2 and the C3, but for some reason I don't have to with this S3 (is that normal behaviour?). But that doesn't work. It doesn't go into download mode, it just runs the program as usual. This also happened before the pin misconfiguration.
-I also tried uploading an empty sketch via the UART0 pins using an FTDI USB to serial converter. However it fails to connect (yes I am using the 499 resistor). I know the FTDI board works, I've used it before without any issues and I've also checked the wiring and switch the pins around in case I got it wrong. I figured that I might be doing something wrong here, and I suspect that it also might be the most reliable way to get out of this situation.

Let me know if/what other resources might be of help (pictures, schematics, videos, you name it).

Putting it into download mode should both get you your USB upload functionality back as well as allow UART download. How are you forcing download mode, could there be something going wrong there?

This is the part where I start to doubt myself sometimes. I've included a screenshot of my reset and boot select switch. I also used this on the ESP32-C3 board that I made earlier and it worked there, although of course with a different boot select pin. What I am currently doing to get into download mode is hold the boot select button, a short press on the EN button to restart the MCU and then let go of the boot button. From what I have gathered that is how you are supposed to get the ESP32-S3 into download mode. I am hoping that I am actually doing something wrong here, because that would be easy to fix.

No, that should work. Given you still have the UART connected, what does it say when you try to boot into download mode? (Also, you may want to remove C6, if everything works it makes your device always come up in download mode, which you generally don't want.)

That's the thing, UART does not work. I've used it before to program other microcontrollers and I know that the FTDI chip works, but for some reason the ESP32 isn't responding or sending any data. Sometimes when I have it connected via USB, I am lucky and the arduino IDE shows the startup message with the (what I assume is) chip build date and some other info, I don't completely remember what it says. This is done before the firmware I uploaded starts doing its thing, after that the USB data negative pin goes to 1V.

Correction to my last post (which hopefully gets approved before this one so it makes sense). UART does it fact work, but I still can't upload an new (empty) sketch, even when I try putting it into download mode(I also removed the C6 cap). Below is a picture of what the ESP spews out before it starts running my faulty program. Although I haven't seen the last bit before.