
AN3127
High-definition multimedia interface, consumer electronics control (HDMI-CEC)
Doc ID 16896 Rev 2
Whenever a new physical address (other than F.F.F.F) is discovered, a CEC device should:
●
allocate the logical address (see
Section 1.4.7: Logical address allocation
●
report the association between its logical and physical addresses by broadcasting
<Report Physical Address>
This process allows any node to create a map of physical connections to logical addresses.
1.4.6 Logical
addressing
Apart from the physical address, each device appearing on the control signal line has a
unique logical address. This address defines a device type as well as being a unique
identifier. This address is 0 for a TV set with physical address 0b0000 and 14 or even 15
otherwise. It is defined in the CEC_OAR register and in the upper nibble of the first byte of
the transmitted message. All CEC devices therefore have both a physical and a logical
address, whereas non-CEC devices only have a physical address.
1.4.7 Logical
address
allocation
Note that a logical address should only be allocated when a device has a valid physical
address (i.e. not F.F.F.F), at all other times a device should take the ‘Unregistered’ logical
address (15).
Only the device at physical address 0.0.0.0 may take logical address TV (0). A TV at any
other physical address will take the ‘free use’ (14) address. If address 14 is already
allocated it will take the ‘unregistered’ address (15).
Table 1.
Logical addresses
Address
Device
0
TV
1
Recording device 1
2
Recording device 2
3
Tuner 1
4
Playback device 1
5
Audio system
6
Tuner 2
7
Tuner 3
8
Playback device 2
9
Recording device 3
10
Tuner 4
11
Playback device 3
12
Reserved
13
Reserved
14
Free use
15
Unregistered (as initiator address) broadcast (as destination
address)