ESP32 Forum

My thinking is that you could run make monitor at any time (or screen or some other terminal emulator). When you put the board into flash mode, you should see the following messages:
If we aren't seeing this then we should investigate why aren't we seeing this.

Update: we discovered a manufacturing error in the board. Now fixed.

When I execute "make flash monitor", I now get a different error message:

$ make flash monitor
Flashing binaries to serial port COM7 (app at offset 0x10000)...
esptool.py v2.3.1
Connecting........_____....._____....._____....._____....._____....._____....._____....._____....._____....._____

A fatal error occurred: Failed to connect to ESP32: Invalid head of packet ('w')
make: *** [/c/esp-idf-release-v3.0/components/esptool_py/Makefile.projbuild:55: flash] Error 2

When I execute "make monitor" I get this:

--- idf_monitor on COM7 115200 ---
--- Quit: Ctrl+] | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H ---

Which is coming from the local program, not the target. No combination of button pushing/holding provokes the target into any output.

Hmmm ... that is not good. The way to understand what is going on is that there is a serial (UART) input and output signal connected to the ESP32. Over this signal one sends and receives data. This is the primary interaction with the ESP32. It is where console messages FROM ESP32 are sent and where new code is written TO the ESP32 in order to flash new code. When an ESP32 boots (in any either normal or flash mode) it will write messages down its TX line to be received on the RX line of your PC attached serial.

If I were in your shoes, what I'd do now is attach a logic probe to the TX and RX lines of the ESP32 and see what (if anything) is flowing. If nothing, then we have an even bigger mystery. I suspect that you will see data ... we then need to follow that data to see where it goes and where it is being lost. What is the schematic of the RX/TX from the ESP32? Are you using a UART->USB module/component? How confident are you that the TX signals coming out of the physical ESP32 are making their way to your PC?

If I were in your shoes, what I'd do now is attach a logic probe to the TX and RX lines of the ESP32 and see what (if anything) is flowing. If nothing, then we have an even bigger mystery. I suspect that you will see data ... we then need to follow that data to see where it goes and where it is being lost. What is the schematic of the RX/TX from the ESP32?

Our board is intended to be as identical to the WROOM as possible. (I hope this is an answer.)

Are you using a UART->USB module/component?

Yes.

How confident are you that the TX signals coming out of the physical ESP32 are making their way to your PC?

Not at all...in fact, I'd bet they're not. I'll take your suggestion to the HW guy and have him take a closer look. Thanks...

It turns out that the USB to UART bridge we're using I(a Silicon Labs CP210x) needed a hardware handshake line...the HW guy tied CTS high. Interestingly enough, I *still* don't get any output when I run make monitor, but I do when I run PuTTY. Weird, but not a showstopper, at least not for now.

Thanks for all the assistance.

Hello, I have the same problem, but the upload has worked until a few minutes ago, when it stopped. Now it doesn't let me upload and nothing helps.

It doesn't work. I'm not going to buy the DOIT DevKit again, because the buttons do nothing to make the upload happen.

I didn't have any trouble uploading to my WeMos/8266. This is the only ESP32 board I've had access to.

This is a huge problem, and you should really fix it. Uploading is half of having a microcrontroller.