ESP32-GATEWAY-EA - Flashing fails - strange signal levels ESP_EN GPIO0

Started by makimu, February 06, 2021, 08:58:31 pm

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I recently got my ESP32-GATEWAY-EA (Rev. G) plus housing and tried to flash demo code to the device.

The only connection (excluding the osci probes) is a USB cable to the computer where I execute "ESD-IDF: Flash (UART) your project" on the ESP32_Gateway_Ethernet_v4.0 Example from your github repo in Visual Studio Code with ESP-IDF plugin. 

Unfortunately flashing always fails.
"Failed to connect to Espressif device: Timed out waiting for packet header"

So I connected an osilloscope to monitor the two relevant signals during the flashing attempt: ESP_EN (via Extension:Pin3) and GPIO0 (via D4:Pin2). The result is attached.

The good news: The CH340T seems to work. There are signals visible.

First question: How would this sequence look like correctly?

I don't know what this would look like correctly, but these signals look odd to me. ESP_EN is not limited to 3.3 V although directly connected to the ESP-Module. GPIO0 does not reach clear 0V.

Do you have any ideas or hints what is going wrong here?


I would suggest testing with all USBs, then with another computer and another USB cable. Pretty sure it is related to UBS timings.

Re-install CH340T drivers (despite seeing it recognized).

This is very popular error message. It depends on a lot of factors but usually related to USB timings. Search for "ch340 Failed to connect to Espressif device: Timed out waiting for packet header".

Sometimes I regret we went for the auto-reset sequence on the board and didn't just solder a reset button. Yes, that would have made it harder for customers to program (by requiring two-button sequence every time the board has to be programmed) but would have made it more consistent.
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