All sorted guys. It was a hardware issue. Thanks to all!

Try MTDI pull HIGH. When MTDI is wrongly pulled then you can enter download mode:

"waiting for download"

but you wont be able to upload code, it will end up with something like that:

Uploading stub...
Running stub...
Stub running...
Changing baud rate to 921600
Changed.
Configuring flash ...

If you get "waiting for download" you're doing the strapping correctly. Could be a problem with the tx of your usb adapter.


I did a quick check of the Tx of the USB adaptor, using a serial monitor and shorting the Tx and Rx. I'm echoing back all transmits so I think the Tx is functional?

Hi guys,

I'm working with an inherited custom board which is using an esp32-d0wdq6. When programming I get an error stating "Failed to connect to ESP32: Timed out waiting for packet header" and "ESP32 Chip sync error esp_sync_blocking" .

I have tried various programming tools to flash the chip ...