Re: serial console on Pi Zero W

[Pouya Tafti <pouya+lists.netbsd%nohup.io@localhost>]

Many thanks for all the replies!  I merged all my responses
into one.  Didn't manage to get it to work yet.

Perhaps I'm going the hard way about this and there is a
simple way to get a serial console on the Pi Zero W USB
output instead of the GPIO UART pins?

From mouse%Rodents-Montreal.ORG@localhost Sun Aug 22 23:46:39 2021
[snip]
> If you're an experienced serial-line hacker, what I'm about to say will
> be obvious to you, but it's not clear to me whether you are or not.

> Are you certain you don't need to swap Tx and Rx?

Not an experienced serial hacker but I do use it
occasionally.  There is a tiny LED on the bridge that
lights up when I type on the laptop so I assume I got Tx
and Rx right.  But to be sure I tried swapping them, which
made no difference.

[snip]


From ckulesa%arizona.edu@localhost Sun Aug 22 23:51:49 2021
> To clarify, you are connecting to the TX, RX, and GND pins on the GPIO 
> header?

Yes, to pins 6 (GND), 8 (UART TX), and 10 (UART RX) as per
here, to be exact:

https://pinout.xyz

> Is this particular cp2102 converter a "true" RS232 UART or is it 
> TTL-level?  The former won't work.  If you've used this converter on 
> another RPI, it should be OK.

Haven't used it on another RPi.

> I use this for RPI, but any converter where logic "high" is 3.3V and 
> "low" is 0V should work.

Checked with a multimeter.  Logic levels seem to be 3.3V
but active low.  Does it need to be active high?

> Can you confirm the pin assighments?  Is the converter RX connected to 
> the PI on the TX pin?  And the converter TX connected to the Pi's RX 
> pin?  If they're reversed, you won't see anything either.

Confirmed but reversing them also makes no difference.

[snip]


From denis%ovsienko.info@localhost Mon Aug 23 00:12:59 2021
> It is not clear from the datasheets whether CP2102 operates its serial
> side at TTL voltage (3.3V) or not.

From a multimeter test it's 3.3V active low.

[snip]