UG-707
ADV8005 Hardware Reference Manual
shows how to implement software to read EDID from the downstream sink using the
Power up Tx via
SYSTEM_PD
START
Wait for HPD
interrupt HDP_INT
Wait for EDID
Ready Interrupt
EDID_READY_INT
Read EDID data
from TX EDID
Map
Parse EDID
Data
Need
Additional
Blocks?
Set
EDID_SEGMENT
desired Segment
Disable EDID
Interrupt
EDID_READY_INT
until next HPD
Setup Audio and
Video
YES
NO
Figure 107: Reading Sink EDID Through ADV8005
6.12.4.
edid_tries Control
can be used to set the number of times the Tx EDID/HDCP controller will try to read the sink EDID after a failure. Each time
an EDID read fails with an I
2
C Not Acknowledged (NACK), this value of
is decremented. Once the
value 0, the Tx EDID/HDCP controller will not attempt to read the EDID until
is set to a value other than 0. This could be used
if a sink asserts high its HPD signal before the DDC bus is ready, resulting in several NACKs as the
edid_tries[3:0]
, TX2 Main Map,
Address 0xF4C9[3:0]
This signal is used to control the number of times that the EDID read will be attempted if unsuccessful.
Function
edid_tries[3:0]
Description
xxxx
Number of time the EDID/HDCP controller attempts to read the EDID
6.12.5.
EDID Reread Control
If the EDID data from the sink is read in and the host determines that the data needs to be reread,
can be set from 0 to 1, and the
will be reread. Rereading the sink EDID may be useful, for example, if the host finds that one EDID
checksum read from the sink is invalid.
Note:
It is also possible to reread the EDID from the sink by toggling the Tx core power down
from 0 to 1.
Rev. A | Page 234 of 317
