Re: usb serial - need quirk?

From: Daniel O'Connor via hackers <>
Date: Mon, 29 Nov 2021 08:16:31 UTC

> On 29 Nov 2021, at 18:09, Daniel Braniss <> wrote:
>> On 29 Nov 2021, at 09:24, Daniel O'Connor <> wrote:
>> I had a look at the ESP32-C3 datasheet and it *does* have a USB interface built in and it talks about a CDC-ACM virtual serial port which matches what you see.
>> The only ACM quirk I can see is UQ_ASSUME_CM_OVER_DATA so you could try that I suppose..
>> (See the usb_quirk man page)
> i’ll try this ASAP, thanks
> BTW, looking at the m5 stamp c3 diagram, I can’t see how the usb-typec is connected to the esp32c3
> from the esp32c3 docs, it’s gpio9 that needs to be grounded to flash, and I don’t see that happening when
> using the onboard usb.
> oh well,

The schematic at it has a CH9102F and some googling suggests it presents as a CDC ACM device.

It looks like it has RTS and DTR hooked up so they can reset and drive GPIO9 for programming.

Unfortunately I can't see anything obvious about why it doesn't work :(

Daniel O'Connor
"The nice thing about standards is that there
are so many of them to choose from."
 -- Andrew Tanenbaum