The Protocol for the rMP3 employs a simple but robust asynchronous serial control protocol. A command prompt ”>” (“greater than” symbol, ASCII 62, HEX 0x3E) indicates that the rMP3 is ready to accept a command. A command can be sent, a response will be returned, and the command prompt will be sent again.

Example:

If an error occurs while processing a command, an error is returned in the format ”Enn”. See the table of error codes.

Example:

CC«sp»Parameter1«sp»Parameter2«sp»…«cr»

Where:

• CC is the command character(s).
• «sp» is a single space character (ASCII 32, HEX 0x20).
• Parameter1, Parameter2, … are parameters associated with the command
• «cr» is a carriage return character (ASCII 13, HEX 0x0d)

CC Parameter1 [Parameter2 [Parameter3]]…

• CC is the command character(s).
• Parameter1 is the first parameter for the command. Often, this is a sub-command.
• Parameter2 is the second parameter for the command. If it is listed inside of square brackets [ ] then the parameter is optional.

Any parameters listed inside of square brackets [ ] are optional. Most commands that have optional parameters will require the previous parameter to be given.

In general, responses are of the format:

[[«sp»][data]] | [Enn]

Error codes are returned as Enn, where nn is a hexadecimal code indicating the error. See the table of error codes.