Q:

RS232 beginner tutorials

I am really beginner in Linux and in electronics but I want to learn programming hardware using raspberry pi board, since I have one (model B).
I have installed raspbian os, now I want to understand how to connect RS232 and control my raspberry using my Linux PC (I learn how to do it using ssh). For me this is very interesting area but I don't know where to start and how to start.
My problem is I totally don't know how to work with RS232, how to connect it and what should happen if I correctly connect RS232 to my Linux PC.
Can you give some good tutorials for totally  beginners (would be great with some videos)
If I made mistake in question please don't close it, let me know reason I will correct it.
Thanks

A:

If you know nothing about RS232 I'd suggest you start with a different project.
However, there are people who have produced the sort of RS232 interface you mention.

Robert Davage

Adding a RS232 serial port to the Raspberry Pi is actually quite simple.  [All] you need is a RS-232 level shifter and a four wire leads to connect to the GPIO header.  So .. what [is] a level shifter you ask.  A level shifter is a circuit that can take the low voltage (±3.3VDC) TTL signals for serial transmit (TX) and receive (RX) from the UART on the Pi and shift them to ±5VDC the voltage signals required for RS232 standard communication.

Code and Life

So in this short tutorial, I’ll show you how to use a MAX3232CPE transceiver to safely convert the normal UART voltage levels to 3.3V accepted by Raspberry Pi, and connect to the Pi 

MadLab

The Pi has 2 rows of general purpose input / output (GPIO) pins at 3.3V (top left in the picture), but that means that we can’t use an RS232 serial connection directly as the voltage levels are too high. Rather than build or buy a converter, we used a simpler method. Most modern Linux distributions, including Debian Squeeze, provide support for USB serial ports, so getting hold of a USB serial cable was the first job. This connects to one of the USB ports on the Pi, and has a 9 pin D serial connector on the other end.

You can purchase ready-made parts

Ebay example
Pi232 board
FTDI
Sparkfun
Adafruit Raspy Juice

