Monitor stops working, when Download mode is entered (IDFGH-16338)

[jrahlf]

Checklist

• Checked the issue tracker for similar issues to ensure this is not a duplicate.
• Provided a clear description of your suggestion.
• Included any relevant context or examples.

Issue or Suggestion Description

I have UART output permanently shown via idf-monitor. I run the firmware and also flash inbetween. I am running on Windows.
The monitor (from esp-idf 5.5) stops working when the device enters download mode and received some data (I am flashing via USB).

The last lines the monitor then shows is

waiting for download
�OHAI��
���

There was no issue with monitor from esp-idf 5.3. It kept running all the time.
I believe this is a bug, because the monitor stops showing anything and also it does not exit on its own.

With the monitor from esp-idf 5.3 it looks like this

waiting for download
�OHAI��
���
--- Warning: Failed to decode multiple lines in a row. Try checking the baud rate and XTAL frequency setting in menuconfig
p��     ��      ��      �� 
<and more >

[peterdragun]

@jrahlf Can you please share the version of esp-idf-monitor that you are using for both versions of ESP-IDF? It is printed as one of the first lines when you start the monitor. Thank you!

[jrahlf]

@peterdragun I have the following two versions (from esp-idf 5.3 and esp-idf 5.5):
Working version: 1.5.0
Not working version: 1.7.0

[peterdragun]

@jrahlf Please note that the workflow that you mentioned - monitoring the device while flashing on the same port - is not supported. We have even introduced advisory port locking, which should make esp-idf-monitor or esptool fail if the other has already opened the port. I don't think this locking works properly on Windows because of a driver issue. (This was introduced in esp-idf-monitor v1.4.0, so your version should already include it, but it seems to work for you without failing) This was introduced to make sure that the data from the chip ends up in the application that expects it.

If you need to monitor the chip while flashing, I would recommend doing that on a different interface (e.g., our newer devkits include 2 USB ports - UART and USB Serial/JTAG port).

I will try to take a look to see what could have caused the difference/issue that you are seeing, and investigate if we can produce an exit in this case.

[jrahlf]

@peterdragun
I am flashing via USB, monitoring is done via UART (with external UART-USB converter), never on the same interface.
My device is an esp32s3.

[peterdragun]

@jrahlf Oh, I am sorry for misunderstanding. Now I can reproduce the issue, and you are right, this should not happen. Seems like this was broken in esp-idf-monitor 1.6.0. I will try to provide a fix soon. One thing that I noticed is that if you change the ports - monitor on USB and flash using UART - everything seems to work as expected for me.

Thank you for the report!