ESP32 Forum

Hello everybody,

currently I am working on a self developed PCB with a WROOM-ESP32 on board. The PCB is a new design, got it delivered today. The ESP32 is unprogrammed.
I did develop the firmware on a devboard.
I can't programm the ESP32, neither with "esptool" nor in the build environment ("make flash").
The result is always:
Connecting........_____....._____....._____....._____....._____....._____....._____....._____....._____....._____
A fatal error occurred: Failed to connect to Espressif device: Invalid head of packet ('\x00')

Things I did:
[*] connected the ESP32-UART (wroom pin 34/34=rxd/txd) to a serial-USB-converter connected to my PC.
[*] verified correct COM port in device manager (COM14)
[*] set up build environment to correct COM port (export ESPPORT=COM14)
[*] I did look at the signals using an oscilloscope - there is data TX'd to the ESP32
[*] I testwise exchanged TX and RX - same result

How can I process further and narrow down this problem?
Thanks in advance for any input.

Best Regards, Timm

Hello,

thank you for your response.
I verified that GPIO0 and GPIO2 are low at power up of module.
Then, I release GPIO0 and afterwards start the program process.
Still, I can't program the device.
Serial data is being sent towards the ESP32 and I can measure it at pin 34/rxd. Level is ok, 3,3V.
The ESP32 doesn't answer on the txd pin.

Any other ideas?
Thanks in advance.

I'm surprised that you would develop your own board without even having the experience of using a $10 devkit board. You should be seeing a message on the terminal saying that it's ready for download. The BOOT pin GPIO 0 should be low, then the EN (CHIP_PU) pin should be used to reset. At that point you should see a "Waiting for download" message.

At least that's my understanding. If I'm wrong someone will be along shortly to set me straight.

John A

Are you sure you have correct program port pins

https://c1.staticflickr.com/5/4721/4010 ... 65f2_b.jpg

JTAG lines can be sensitive. Can you post a oscilloscope screenshot of the lines?

Hello,

thanks very much for the help to everybody who contributed!
The problem was a hardware issue with the power supply on our PCB.
Now, I can program the board.
P.S. can I mark the thread as solved in any way?

Best Regards, Timm

timm_f wrote:Hello,

thanks very much for the help to everybody who contributed!
The problem was a hardware issue with the power supply on our PCB.
Now, I can program the board.
P.S. can I mark the thread as solved in any way?

Best Regards, Timm

you can edit the title and add a [SOLVED] tag