
High-definition multimedia interface, consumer electronics control (HDMI-CEC)
AN3127
Doc ID 16896 Rev 2
Reserved addresses should not be used at present and are reserved for future extensions
to this specification.
Where more than one possible logical address is available for the given device type (e.g.
Tuner 1, Tuner 2, etc.), an address allocation procedure should be carried out by a newly
connected device. The device takes the first allocated address for that device type and
sends a <Polling Message> to the same address (e.g. Tuner 1 -->Tuner 1). If the <Polling
Message> is not acknowledged, then the device stops the procedure and retains that
address.
If the first address is acknowledged, then the device takes the next address for that device
type and repeats the process (e.g. Tuner 2 .. Tuner 2). Again, if the message is not
acknowledged, the device keeps that address.
This procedure continues until all possible ‘type-specific’ addresses have been checked; if
no ‘type-specific’ addresses are available the device should take the unregistered address
(15). Note that several physical devices might be sharing this address.
A device may lose its logical address when it is disconnected or switched off. However, it
may remember its previous logical address, so that the next time it is connected or switched
on, it can begin the polling process at its previous logical address and try each other
allowable logical address in sequence before taking the unregistered address. For example
if an STB that was previously allocated address Tuner 2 is reconnected, it would poll Tuner
2, Tuner 3, Tuner 4 and Tuner 1 before taking the unregistered address.
If a device loses its physical address at any time (e.g. it is unplugged) then its logical
address should be set to unregistered (15).
1.5
STM32F100xx’s HDMI-CEC controller
The STM32F100xx’s HDMI-CEC controller provides a hardware support of the CEC
protocol.