
REV. 0
AD9887
–25–
2-Wire Serial Register Map
The AD9887 is initialized and controlled by a set of registers, which determine the operating modes. An external controller is
employed to write and read the Control Registers through the 2-line serial interface port.
Table IX. Control Register Map
Read and
Hex
Write or
Default
Register
Address
Read Only
Bits
Value
Name
Function
00H
RO
7:0
Chip Revision
Bits 7 through 4 represent functional revisions to the analog interface.
Bits 3 through 0 represent nonfunctional related revisions.
Revision 0 = 0000 0000
01H
R/
W
7:0
01101001
PLL Div MSB
This register is for Bits [11:4] of the PLL divider. Larger values mean
the PLL operates at a faster rate. This register should be loaded rst
whenever a change is needed. (This will give the PLL more time to
lock.) See Note 1.
02H
R/
W
7:4
1101
****
PLL Div LSB
Bits [7:4] LSBs of the PLL divider word. See Note 1.
03H
R/
W
7:2
1
*******
VCO/CPMP
Bit 7—Must be set to 1 for proper device operation.
*01*****
Bits [6:5] VCO Range. Selects VCO frequency range. (See PLL
description.)
***001**
Bits [4:2] Charge Pump Current. Varies the current that drives the
low-pass lter. (See PLL description.)
04H
R/
W
7:3
10000
***
Phase Adjust
ADC Clock phase adjustment. Larger values mean more delay.
(1 LSB = T/32)
05H
R/
W
7:0
10000000
Clamp
Places the Clamp signal an integer number of clock periods after the trail-
Placement
ing edge of the Hsync signal.
06H
R/
W
7:0
10000000
Clamp
Number of clock periods that the Clamp signal is actively clamping.
Duration
07H
R/
W
7:0
00100000
Hsync Output
Sets the number of pixel clocks that HSOUT will remain active.
Pulsewidth
08H
R/
W
7:0
10000000
Red Gain
Controls ADC input range (Contrast) of each respective channel.
Bigger values give less contrast.
09H
R/
W
7:0
10000000
Green Gain
0AH
R/
W
7:0
10000000
Blue Gain
0BH
R/
W
7:1
1000000
*
Red Offset
Controls dc offset (Brightness) of each respective channel. Bigger
values decrease brightness.
0CH
R/
W
7:1
1000000
*
Green Offset
0DH
R/
W
7:1
1000000
*
Blue Offset
0EH
R/
W
7:3
1
*******
Mode
Bit 7—Channel Mode. Determines Single Channel or Dual Channel
Control 1
Output Mode. (Logic 0 = Single Channel Mode, Logic 1 = Dual
Channel Mode.)
*1******
Bit 6—Output Mode. Determine Interleaved or Parallel Output Mode.
(Logic 0 = Interleaved Mode, Logic 1 = Parallel Mode.)
**0*****
Bit 5—OUTPHASE. Determines which port outputs the rst data byte
after Hsync. (Logic 0 = B Port, Logic 1 = A Port.)
***0****
Bit 4—Hsync Output polarity. (Logic 0 = Logic High Sync, Logic 1 =
Logic Low Sync.)
****0***
Bit 3—Vsync Output Invert. (Logic 0 = Invert, Logic 1 = No Invert.)
OBSOLETE