I always forget howto connect with a serial cable to a device when I don’t have minicom installed..
So this is a writeup for my own poor memory :)

In this example we use a real tty serial connector [/dev/ttyS0], not a modern USB2Serial converter [/dev/ttyUSB0] :)

First add yourself to dialup group.

sudo adduser $USER dialout

Logout, login..

screen

This will connect with 9600 baud default.

screen /dev/ttyS0

Is you want lightning speed like 115200

screen /dev/ttyS0 115200

minicom

Somewhat more strange to config imho.
First time setup:

minicom -s

+--------------------------------------------+
| A -    Serial Device      : /dev/ttyS0     |
| B - Lockfile Location     : /var/lock      |
| C -   Callin Program      :                |
| D -  Callout Program      :                |
| E -    Bps/Par/Bits       : 115200 8N1     |
| F - Hardware Flow Control : No             |
| G - Software Flow Control : No             |
|                                            |
|    Change which setting?                   |
+--------------------------------------------+

Then change the settings you want to connect to.
A - device
E - speed

Then next time, just run:

minicom

cu

The leanest one if you ask me.

cu -l /dev/ttyS0 -s 115200

If you know a more and easier ways than this, and it certainly you do, pls send in a comment below…

And at last do not forget your well earned Coffee.