adv3002 Analog Devices, Inc., adv3002 Datasheet - Page 14

• Manufacturer Part Number: adv3002
• Description: 4 1 Hdmi/dvi Switch With Equalization, Ddc/cec Buffers And Edid Replication
• Manufacturer: Analog Devices, Inc.

ADV3002
Source Physical Address Assignment
In HDTV applications where the CEC function is available, the
EDID contains the source physical address (SPA); a unique value
for each HDMI port. Because the memory in the ADV3002 is
volatile, the SPA must be stored in the external EDID EEPROM.
Rather than require a larger external EEPROM to store the SPA,
because all 256 bytes of memory are needed for typical EDID
information, the ADV3002 takes advantage of EDID information
that is always a fixed value, such as the 24-bit IEEE registration
identifier (0x000C03). The 24 bits of the IEEE registration identifier
are replaced with the desired SPA values. When a source requests
the IEEE registration identifier, the ADV3002 responds with the
fixed value (0x000C03). The ADV3002 then automatically calcu-
lates the correct checksum for each port based on the SPA stored
for that port in the vendor specific data block (VSDB).
CEC enabled devices have a source physical address (SPA) that
allows the CEC controller to address the specific physical devices
and control switches. The SPA is comprised of four fields or
nibbles. Each field is a 4-bit number; therefore, each field can be
any one of 16 possible values (0x0 through 0xF). Each HDMI
input port is assigned a unique SPA as shown in Figure 24. In any
CEC enabled device, only one of the four fields is unique per port.
In HDMI sink applications, where the sink is the root device, only
the W field is unique per port, whereas the X, Y, and Z fields are
always set to zero.
A typical vendor specific data block (VSDB) is shown in Table 7.
When using the ADV3002 EDID replicator, the VSDB should
be replaced with the one shown in Table 8, whereby the port
specific field can be assigned to any of the four fields (W, X, Y, or Z)
depending on the value set in the override select bits as shown in
Table 9.
When calculating the checksum for Block 1 of the EDID, the custom
values entered in place of the IEEE registration identifier should
not be used in the calculation; instead, the IEEE registration iden-
tifier values should be used (0x000C03). The values in Byte 4 and
Byte 5 of the VSDB should be included in the calculation.
SPA = W. X. Y. Z
Rev. 0 | Page 14 of 28
Table 7. Typical Vendor Specific Data Block (VSDB)
Byte No.
0
1
2
3
4
5
6 to N
Table 8. Vendor Specific Data Block with ADV3002
Byte No.
0
1
2
3
4
5
6 to N
Table 9. Override Select Assignment
Bit 3
1
0
0
0
Override Select
Bit 2
0
1
0
0
Remainder or VSDB is stored in Byte 6 through Byte N
7
Port A SPA override field
Port C SPA override field
Not used
Default W field
Default Y field
7
Vendor specific tag code
Remainder or VSDB is stored in Byte 6 through Byte N
Vendor specific
tag code (= 3)
SPA = W
SPA = W
SPA = W
SPA = W
Bit 1
0
0
1
0
24-bit IEEE registration identifier (0x000C03)
6
PORT A
PORT B
PORT C
PORT D
HDMI
HDMI
HDMI
HDMI
A
B
C
D
6
Figure 24. SPA Assignments
. X
. X
. X
. X
(= 3)
SPA Field W
SPA Field Y
Bit 0
0
0
0
1
A
B
C
D
. Y
. Y
. Y
. Y
(least significant byte first)
A
B
C
D
5
. Z
. Z
. Z
. Z
A
B
C
D
Field Replaced by Port Specific SPA
W
X
Y
Z
5
4
4
Length (= N)
3
Port B SPA override field
Port D SPA override field
Override select (see Table 9)
Default X field
Default Z field
ADV3002
Length (= N)
3
SPA Field X
SPA Field Z
2
2
1
1
0
0