Device Connectivity And Addressing; Cec Communication; Figure 5. Follower Acknowledge (Ack); Figure 6. Cec And Ddc Line Connections - ST STM32F100 Series Application Note

AN3127 High-definition multimedia interface, consumer electronics control (HDMI-CEC)
CEC Figure 5
assert the bit to logical 0 to acknowledge a data block. The initiator outputs a logical 1, thus
allowing the follower to change the CEC state by pulling the control line low for the duration
of the safe sample period.
Figure 5.
1.4

Device connectivity and addressing

1.4.1

CEC communication

By definition the HDMI system architecture consists of sources and sinks. A given device
may have one or more HDMI input(s) and output(s). Each HDMI input on the device should
follow all the rules for a HDMI sink and each HDMI output should follow all the rules for a
HDMI source.
The DDC is used for configuration and status exchange between a single source and a
single sink. The optional CEC protocol provides high-level control functions between all of
the various audiovisual products in a user's environment.
Figure 6.
shows an example bit with both initiator and follower where the follower may
Follower acknowledge (ACK)
CEC and DDC line connections
Doc ID 16896 Rev 2 9/36