ESP32-C3 Serial.available() doesn't work over native USB - print, printf works fine

[BrianP]

This is a weird one.

I am using USB serial emulation to debug some code. So the native, built in USB controller with no USB to serial chip. I can program the ESP no problem, and Serial.print as well as printf work perfectly.

I have tried using the Arduino serial console, Teraterm and Putty (the latter I can disable flow control). The relevant code fragment is

if( Serial.available() > 0 ) {
input = Serial.read();

I never get a NZ value for Serial.available. I have even tried the Arduino example to the same effect.

I downloaded and installed ESP-IDF, which I expect to install the USB driver, but device manager says it is using the Microsoft driver date 2006, version 10.0.22621.160. Updating the driver has no effect.

Any suggestions?

Thanks!

[BrianP]

I think I figured it out. Pretty hard to find with the googles but for the benefit of the next person look at this reddit reply
https://www.reddit.com/r/esp32/comments ... e/hzoq904/

In my case, I edited board.txt as found at \AppData\Local\Arduino15\packages\esp32\hardware\esp32\2.0.6 and changed the lines

esp32c3.serial.disableDTR=false
esp32c3.serial.disableRTS=false

to

esp32c3.serial.disableDTR=true
esp32c3.serial.disableRTS=true

[0miker0]

Uploading sketches and serial data worked so intermit and poorly for me that I ended up adding a CP2104 usb chip. After that it all worked perfectly. I was hoping after a few updates it would work better but nope.

[BrianP]

I have mostly had to overcome "hurdles" like this one where things don't work, I solve the problem and then they work no problem since then.

I think part of the issue is that internal ESP internal USB challenges are not particularly well documented so you can hit a brick wall pretty easily. Even things like making sure the states of IO2, 8, and 9 (and 9 being used as a boot switch) at bootup should be in bold in the documentation.

So I have been able to program via internal USB without any issues once I figured those things out, and have only had issues with serial emulation with this issue. The issue baffles me because its an Arduino file (boards.txt) and I wasn't using the Arduino serial console.

I'm biased though: I think the Arduino software platform is an abomination but I'm using it so my friend can modify the code after I'm done.