Additional Segments; Figure 98: Reading Sink Edid Through Adv8003 - Analog Devices ADV8003 Hardware Manual

EDID structure defined in the VESA EDID specifications; the second EDID block is usually the CEA extension defined in the CEA-861
specification.
The ADV8003 has a single memory location used to store EDID and HDCP information read from the downstream sink. During HDCP
repeater initialization, the EDID data read from the sink is overwritten with HDCP information which is also read from the sink. The sink
EDID is not reread after HDCP initialization. The user can request the ADV8003 to rebuffer an EDID segment by using the
control.

6.12.3. Additional Segments

The EDID block 0 byte number 0x7E tells how many additional EDID blocks are available. If byte 0x7E is greater than 1, additional EDID
segments will need to be read. If there is more than one segment, the second block (that is, block 1) is required to be an EDID extension
map. This map should be parsed according to the VESA EDID specification to determine where additional EDID blocks are stored in the
sink EDID storage device such as EEPROM, RAM, and so on.
The ADV8003 is capable of accessing up to 256 segments from EDID of the sink as allowed by the EDID specification. By writing the
desired segment number to the
the Tx DDC lines and load the 256 bytes into the EDID/HDCP memory. When the action is complete, the ADV8003 triggers the
edid_ready_int interrupt (refer to Section 6.8). The EDID data read from the sink can then be accessed from the Tx EDID Map. If the host
controller needs access to previously requested EDID information, then it can be stored in its own memory.
Figure 98 shows how to implement software to read EDID from the downstream sink using the ADV8003.
Power up Tx via
SYSTEM_PD
Wait for EDID
Ready Interrupt
EDID_READY_INT
Read EDID data
from TX EDID
Map
Rev. B, August 2013
edid_segment[7:0] field, the ADV8003 will automatically access the correct portion of the sink EDID over
START
Wait for HPD
interrupt HDP_INT
EDID_SEGMENT
Parse EDID
Data

Figure 98: Reading Sink EDID Through ADV8003

Set
desired Segment
Need
NO
Additional
Blocks?
284
ADV8003 Hardware Manual
Disable EDID
Interrupt Setup Audio and
EDID_READY_INT
until next HPD
edid_reread
Video