Tty setup
Contents
Configuring a TTY serial port
tty devices are found in the /dev directory. If you use a USB adapter it will appear as /dev/ttyusb0.
Use the stty command to configure tty devices.
Hardware
Built in UART
The built in UART is connected to the GPIO connector P1. NOTE: These signals are unbuffered 3.3v logic and NOT RS232 OR 5v TTL compatible. To use the built in UART to a standard RS232 device a MAX RS232 chip is required. The MAX3232 is a commonly used chip. The chip itself can run at 3.3 and 5v. You MUST run it off the 3.3v supply if it is connected to the RPi.
USB to RS232
Successful
A PL-2303 based USB to RS2323 adapter work on my Raspbian based Pi without installing additional drivers, although it was not a fully clean install.
Recommended
I have used FTDI devices with other projects, these are also discussed in many Pi forums. I (BillyBag2) have not used these on a Pi myself. These tend to be more expensive.
Not successful
The cheapest adapters are "340" based. HOWEVER I (BillyBag2) was unable to get these to work fully.
