Re: usb CH9102 serial chip

From: Daniel Braniss <danny_at_cs.huji.ac.il>
Date: Thu, 17 Feb 2022 09:34:27 UTC 

> On 17 Feb 2022, at 11:30, Daniel O'Connor <darius@dons.net.au> wrote:
> 
> 
> 
>> On 17 Feb 2022, at 19:50, Daniel Braniss <danny@cs.huji.ac.il> wrote:
>> 
>>> If that is the case then the chip/driver are working fine since that requires bidirectional communication etc..
>>> 
>> 
>> but that works only if I power up the board while pressing a button, then it also appears as /dev/ttyU0, and
>> so then I can flash, after reset, the device is gone and there are errors ( BTW, the flashed image workes):
>> 
>> Feb 17 09:46:59 pampero kernel: usbd_setup_device_desc: getting device descriptor at addr 4 failed, USB_ERR_IOERROR
>> Feb 17 09:47:00 pampero kernel: usbd_req_re_enumerate: addr=4, set address failed! (USB_ERR_IOERROR, ignored)
> 
> What sort of dev board is it?
	m5 stamp C3U
https://shop.m5stack.com/products/m5stamp-c3u-mate-with-pin-headers?_pos=2&_sid=3df9b5f0d&_ss=r&variant=42341016633601 <https://shop.m5stack.com/products/m5stamp-c3u-mate-with-pin-headers?_pos=2&_sid=3df9b5f0d&_ss=r&variant=42341016633601>

> 
> Seems very strange the USB UART would behave differently unless it's wired up in an unusual way IMO.
> 
> --
> Daniel O'Connor
> "The nice thing about standards is that there
> are so many of them to choose from."
> -- Andrew Tanenbaum
> 
>