Serial interface connected to a file
A serial interface can be connected to a file. This might be stdin or a real UART.
The file backend is the most used backend.
Examples:
[usart2]
type: file
file: stdin
Be careful with stdin as uart file backend. Linux terminals like xterm or konsole typically use <NL> as
line termination where most terminal programms like minicom and Hyperterminal use <CR><NL> as line termination. Many embedded applications are not prepared for a missing <CR>.
[uart6]
type: file
file: /dev/ttyUSB0
The NULL UART
The NULL Uart module is the default backend.
If a configuration section for an uart does not exist then the NULL Uart is selected.
This backend eats up all data and emits nothing. It is also possible to configure the uart explicitly:
[uart5]
type: null
Serial interface connected to a Pseudo terminal
Softgun can create a pseudo terminal device using /dev/ptmx. You can use the pseudo terminal
similar to a real serial interface. For example you can connect with minicom to the
pseudo terminal. Because it is not known in advance what the name of the created device
will be softgun can create a link to the device file. Example:
[uart0]
type: ptmx
link: /tmp/pty_myembeddedsystem
Nine or more bits
The ptmx interface is the only one which supports more than 8 Bits per character. Because a ptmx interface emits a stream of bytes the data need to be framed. softgun does this by encoding any data stream with more than eight bits as UTF8. This is of course a misuse of the UTF8 encoding, but it saves me from the need of writing a documentation. If you want to have UTF8 encoding even for 8 bits per character you can force UTF8 mode:
[uartXX]
type: ptmx
utf8: 1
Serial interface connected to a simulated device
You can create own serial interface backends in softgun. For example you might have a gyroscope
with a serial interface. Write a backend called gyroscope which responds to serial queries like the real device, then connect softgun to this backend in the configuration file:
[uart5]
type: gyroscope
