Discovery Algorithm; Figure 8. Physical Address Discovery Algorithm - ST STM32F100 Series Application Note

High-definition multimedia interface, consumer electronics control (HDMI-CEC)
(EDID_EXT_VSDB_B0-1). Thereby, except for the root device, all devices have the physical
address stored in the EDID of their connected sink.
The physical address of each node is determined through the physical address discovery
process. This process is dynamic in that it automatically adjusts physical addresses as
required as devices are physically or electrically added or removed from the device tree.
All sinks and repeaters should perform the steps of physical address discovery and
propagation even if those devices are not CEC-capable. Sources are not required to
determine their own physical address unless they are CEC-capable.
All addresses are 4 digits long allowing for a 5-device-deep hierarchy. All are identified in the
form of n.n.n.n in the following description.
A sink or repeater that is acting as the CEC root device generates its own physical address:
0.0.0.0. The source or repeater reads its physical address from the EDID of the connected
sink. The CEC line may be connected to only one HDMI output so a device with multiple
HDMI outputs will read its physical address from the EDID on the CEC-connected output.
Each sink and repeater is responsible for generating the physical address of all source
devices connected to that device by appending a port number onto its own physical address
and placing that value in the EDID for that port.
1.4.5

Discovery algorithm

The following algorithm is used to allocate the physical address of each device whenever
HPD is de-asserted, or upon power-up:
Figure 8.
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Physical address discovery algorithm
Doc ID 16896 Rev 2
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