Spa Configuration; External E-Edid; Tmds Equalization; Equalizer Read Back - Analog Devices ADV7850 Hardware Manual

Function
spa_port_d[15:0]
0000000000000000 
xxxxxxxxxxxxxxxx
port_d_checksum[7:0], Addr 64 (Repeater), Address 0x63[7:0]
This control is used to set the checksum for the second half of the Port D EDID. This is calculated automatically.
Function
port_d_checksum[7:0]
00000000 
xxxxxxxx

7.11 SPA CONFIGURATION

When the E-EDID/Repeater controller configures the internal E-EDID in cable supply mode, as described in Section 7.5.1, it also updates
the SPA registers for each port according to the SPA read from the external SPI EEPROM. The 2-byte SPA is located at the address
specified by spa_location in addresses 0x7F and 0xFF of the SPI EEPROM. The SPA of each port is set as follows:
•
SPA for Port A located in E-EDID RAM is set to A.B.C.D
• SPA for Port B, spa_port_b[15:0], is set to A+1.B.C.D
•
SPA for Port C, spa_port_c[15:0], is set to A+2.B.C.D
• SPA for Port D, spa_port_d[15:0], is set to A+3.B.C.D
where A.B.C.D is the 2-byte SPA read from the SPI EEPROM. The format A.B.C.D is described in the HDMI specification.

7.12 EXTERNAL E-EDID

It is possible to use an external device such as an EEPROM to store E-EDID data. When an external storage device is used for the E-EDID
data of a specific HDMI port, the storage device must be connected to the DDC lines of that HDMI port. The internal E-EDID should not
be enabled for that specific port.

7.13 TMDS EQUALIZATION

The ADV7850 incorporates active equalization of the HDMI data signals. This equalization compensates for the high frequency losses
inherent in HDMI and DVI cabling, especially at long lengths and higher frequencies. The ADV7850 is capable of equalizing for cable
lengths up to 30 meters and for pixel clock frequencies up to 297 MHz.
Equalization is carried out on the data lines. Equalization is not required on the clock lines. Along with a fully automatic Equalizer, the
Equalizer can be configured in a manual mode.
The Equalizer provides two forms of signal correction. The first signal correct is to gain the full signal to the correct levels. In the
ADV7850 this is called the GCTRL gain. After this stage, the signal is given a high frequency boost. In the ADV7850 this is called the
ZCTRL gain. Both the GCTRL and ZCTRL can be readback in automatic mode and manually programmed if required.

Equalizer Read back

7.13.1
In Automatic mode the automatic values can be read back through the register listed below. The read back values are carried out on a port
by port basis and this is controlled by registers.

Manual Operation

7.13.2
Automatic equalization is recommended in most cable connections. However there may be cases where manual equalization is preferred
for example when there is equalization carried out in the front Mux or buffer.
Rev. A May 2012
Description
Default
Source physical address of Port D
Description
Default
Checksum for E-EDID block containing SPA for Port D
150
ADV7850