Atmel AT83SND2C MP3 - Manual (Page 12)

AT83SND2CMP3 User Guide 3-8
7525A–MP3–07/05
Section 3
Communication Protocol
The AT83SND2CMP3 is remotely controlled using simple ‘user interface like’
commands such as Play or Stop commands. The communication protocol provides an
abstraction of the physical layer between the Remote Controller and the Player.
3.1 Communication
Protocol The communication protocol is a half-duplex protocol between a host Remote Controller
and the AT83SND2CMP3 (Player) over a UART.
Note: In the following discussion, Remote Controller is considered as a ‘master’ and Player as
a ‘slave’.
3.2 Frame Format All the commands at physical layer level shall respect the following frame format:
Figure 3-1 . Communication Protocol Frame Format
The frame format breaks down into the following information:
•
Frame Start (1 byte): Synchronization character 7Eh
• Channel (1 byte): logical channel number (reserved and set to FFh)
• Protocol command (1 byte): refer to command set list.
• Data Length (1byte): data length in byte excluding the Checksum byte.
Data
Frame Start
7Eh
Channel
FFh
Protocol
Command
Data
Length
CheckSum