The rMP3 can read a configuration file on boot (power on/hard reset). Any of the settings can be put into the file.
Only the settings in the file are affected. If a setting is not in the file, it will not change from its current state. For example, if the baud rate is already set to 19200 bps, it will not change unless you add a baud rate setting change in the settings file.
The configuration file contains one setting per line. Lines are terminated with «cr» or «crlf».