[SOLVED] Can't program ESP32 over UART on own PCB

[timm_f]

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

[WiFive]

https://github.com/espressif/esptool/wi ... -Selection

[timm_f]

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.

[fly135]

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

[WiFive]

Are you sure you have correct program port pins

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

[hassan789]

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

[timm_f]

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

[hassan789]

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

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