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Re: serial console on Pi Zero W

On Sun, 22 Aug 2021 23:10:22 +0200
Pouya Tafti <pouya+lists.netbsd%nohup.io@localhost> wrote:

> I've hooked up the Pi to my laptop via
> a cp2102 USB-to-UART bridge.

It is not clear from the datasheets whether CP2102 operates its serial
side at TTL voltage (3.3V) or not. It might be RS-232 levels (5V or
12V). The simplest way to tell would be using a multimeter (on the DTR
pin, for example), if possible.

The matter is, Pi 40-pin header expects TTL on the UART pins, so it
needs a USB-TTL converter. 12V will easily fry the TTL UART in Pi.
Consequently, 3.3V coming out of TTL UART Tx will not register on a 12V
RS-232 Rx. Another common pitfall is, if the USB-TTL converter has a 5V
DC wire (usually red), make sure it is never connected to Pi. That wire
is meant for Arduino.

    Denis Ovsienko

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