Introduction
This specification provides the communication protocol that
allows two-way communication between an RS-232 enabled
controller and an Apple
®
iPod™ docked into an RS-232 enabled
enabled iPort™ model. This document specifies telegrams that
will allow for the command and control of the docked iPod in
extended interface mode and for receiving meta data from the
iPod for display on the controller’s display.
Applicable iPort Models
This specification only applies to iPort models that are two-way
communication enabled. Two-way communication is enabled in
the IW-4 and IW-5 systems, and can be added to iPort IW-2 and
IW-3 systems by adding the iPort RS-232 Upgrade Kit (sold
separately) to the IW-3, and the iPort RS-232 and the iPort
Balanced Audio Upgrade kits (both sold separately) to the IW-2.
Summary of RS-232 Operation
This communication protocol is enabled when the iPod is in
extended interface mode, which can be determined by checking
the iPod screen. The iPort logo will be on the iPod screen when
in extended interface mode.
NOTE: The iPod interface is disabled when in two-way
(RS-232) mode. The user will no longer be able to
control the iPod from the iPod when in two-way mode.
There are commands to enter two way and exit two way. One
may wish to make these commands available to the customer
through the user interface. Refer to section 35 and section 36.
NOTE: If the iPod is docked while in the
Play
mode it
will automatically enter the
Pause
mode. This is due to
the iPod protocol. You may wish to set the RS-232
control system to automatically send a
Play
command to
return the iPod to the last playing song when it is
inserted in the dock.
Connection Description
The iPort communication protocol uses an RJ-11 connector on
the Balanced Audio Wallplate or external break-out box.
(A compatible RJ-11/DB-9 cable is supplied with RS-232 enabled
iPort systems and the iPort RS-232 Upgrade Kit.)
The pin assignments for the RS-232 cable are:
RJ-11 Pin
DB-9
Name
1
2
PC Rx
2*
5
GND
3*
5
GND
4
3
PC Tx
5
2
PC Rx
6
N/A
* Only one GND pin may be connected, if desired.
Com Port Settings:
Baud Rate = 19200
Parity = N
Stop Bits = 1
Data Bits = 8
Packet Structure
The iPort communication packet structure is constructed using a
combination of ASCII characters and hex data. A packet consists
of seven elements described below.
Byte Number Value
Meaning
0x00
0x2A
Start character
0x01
0x49
Device type (iPort)
0x02
0xNN
Packet Length High Byte
0x03
0xNN
Packet Length Low Byte
0x04
0xNN
Packet Command Type
0x05
0xNN
Packet Command High Byte
0x06
0xNN
Packet Command Low Byte
0x07 – 0xNN
0xNN
Packet Data Bytes
0xNN
0xNN
Checksum = 2’s compliment of the
sum of all bytes excluding the start
character and checksum
Packet Command Type:
Code
Command Type
0x38
Two-Way
0x3C
General
0x01*
LED control
* Device type code for this command is 0x4D
Instruction Manual
iPort RS-232 Programming
1
