hmp8112a Harris Corporation, hmp8112a Datasheet - Page 17

• Manufacturer Part Number: hmp8112a
• Description: Ntsc/pal Video Decoder
• Manufacturer: Harris Corporation

NUMBER
NUMBER
NUMBER
15 - 8
7 - 0
7 - 0
BIT
BIT
BIT
Color Saturation
Adjust Factor
PLL Clock
Frequency Ratio
(LSB)
PLL Clock
Frequency Ratio
(MSB)
FUNCTION
FUNCTION
FUNCTION
This register sets the color saturation adjust factor. This value is multiplied by the chromi-
nance (CbCr) data and allows the data to be scaled from 0 to a factor of +1.996. This 8-bit
number is a fractional number as shown below:
The default saturation factor of 1.2266 is calculated as follows:
These bits are used to program the ratio of the incoming video chrominance color sub-
carrier frequency to the input clock (CLK) used. This number serves as the reference fre-
quency of the chrominance PLL. This is the lower byte (LSB) of the ratio and
encompasses the following range:
The default value is for a CLK frequency of 27MHz and a color subcarrier of 3.579545
MHz. The register data is calculated as follows:
Ratio =(4 x fSC) / CLK
=(4 x 3.579545MHz) / 27MHz
Register Data: Ratio * 65536
0.530303 * 65536
34753.94
Convert to Hex:0x87C1
Reg 0x06 LSB =0xC1
Reg 0x07 MSB =0x87
Refer to Table 1 for common PLL Ratio values with CLKs of 27MHz or 24.54Hz
This is the upper data byte (MSB) of the PLL Clock Freq as described in Reg 0x06 above
and encompasses the following range:
=0.530303
TABLE 11. COLOR SATURATION ADJUST FACTOR
TABLE 13. PLL CLOCK FREQUENCY RATIO (MSB)
TABLE 12. PLL CLOCK FREQUENCY RATIO (LSB)
2
Register Data = Factor * 128 = 1.2266 * 128 = 157 = 0x9D
2
2
0
-9
-1
2
2
2
-1
-10
-2
2
2
-2
2
-3
-11
2
2
-3
-4
2
SUB ADDRESS = 0x05
SUB ADDRESS = 0x06
SUB ADDRESS = 0x07
2
-12
2
-4
-5
HMP8112A
2
2
2
-5
-13
-6
2
2
-6
2
4-17
-7
-14
2
2
-7
-8
2
DESCRIPTION
DESCRIPTION
DESCRIPTION
-15
2
-16
1001 1101
1100 0001
1000 0111
RESET
STATE
RESET
STATE
RESET
STATE
(0x9D)
(0xC1)
(0x87)
B
B
B