cx25870 Conexant Systems, Inc., cx25870 Datasheet - Page 90

• Manufacturer Part Number: cx25870
• Description: Video Encoder With Adaptive Flicker Filtering And Hdtv Output
• Manufacturer: Conexant Systems, Inc.

1.0 Functional Description
1.3 Device Description
1-74
Finally, calculate the values for the MSC_DB[31:0], MCR[7:0], MCB[7:0],
FILFSCONV[5:0], FIL4286INCR[7:0], and MSC[31:0] registers for the particular
SECAM overscan solution. To accomplish this task, read back both values that
comprise the HCLKO[11:0] register, convert it to decimal (base 10), and use it in the
equations below. After solving each SECAM register equation, perform a conversion
back to a hexadecimal number and program the appropriate registers with their new
SECAM specific values.
are:
For RGB input only:
For YCrCb input only:
The equations for generation of a SECAM output based on a RGB input only
MSC_DB[31:0] = int ((272 / H_CLKO[11:0]) * 2
DR_LIMITP[10:0] = ((4.756 MHz/ Internal Pixel Clock Frequency)*2^13)
DR_LIMITN[10:0] = ((3.9 MHz/ Internal Pixel Clock Frequency)*2^13)
DB_LIMITP[10:0] = ((4.756 MHz/ Internal Pixel Clock Frequency)*2^13)
DB_LIMITN[10:0] = ((3.9 MHz/ Internal Pixel Clock Frequency)*2^13)
FIL4286INCR[7:0]: Six equations required to find hex value
FILFSCONV[5:0] = int((27 * H_CLKO[11:0] * 1.087) / 1728 + 0.5)
MCR[7:0] = int ((920.26) / (288036.0 * H_CLKO[11:0] * SINX) * 2
MCB[7:0] = int ((598.15) / (288036.0 * H_CLKO[11:0] * SINX) * 2
MSC[31:0] = int ((282 / H_CLKO[11:0]) * 2
MY = same as PAL, no change required for SECAM
MCR[7:0] = int
(1.902/(224*0.713)*(0.28/Fclk)/(84*SINX)*2
MCB[7:0] = int
(1.505/(224*0.564)*(0.28/Fclk)/(84*SINX)*2
MY = same as PAL, no change required for SECAM
•If PLL_CLK32 is 0, then Internal Pixel Clock Frequency = CLKI =
•If PLL_CLK32 is 1(for some overscan ratios in 800x600 and all 1024x768
where SINX = [sin (p * Fsc / CLKI)] / (p * Fsc / CLKI)
where SINX = [sin (p * Fsc / CLKI)] / (p * Fsc / CLKI)
CLKO.
resolutions), then Internal Pixel Clock Frequency = (2/3) * CLKI
SCINCR_OFF = int(8192 * 4.286 * 1728 / (27 * H_CLKO[11:0]) +
0.5)
SCINCR_OFFh = dec2hex(SCINCR_OFF)
SCINCR_OFFb = hex2bin(SCINCR_OFFh)
SCINCR_INTb = SCINCR_OFFb &(bitwise AND operator) with
111111111(binary)
SCINCR_INTnot = NOT[SCINCR_INTb]
FIL4286INCR[7:0] = [BIN2DEC{SCINCR_INTnot}]
Conexant
Flicker-Free Video Encoder with Ultrascale Technology
2
32
27
27
+ 0.5)
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+0.5)
32
+ 0.5)
CX25870/871
26
26
100381B
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