1.0 Functional Description
CX25870/871
1.3 Device Description
Flicker-Free Video Encoder with Ultrascale Technology
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.
The equations for generation of a SECAM output based on a RGB input only
are:
MSC_DB[31:0] = int ((272 / H_CLKO[11:0]) * 232 + 0.5)
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)
•If PLL_CLK32 is 0, then Internal Pixel Clock Frequency = CLKI =
CLKO.
•If PLL_CLK32 is 1(for some overscan ratios in 800x600 and all 1024x768
resolutions), then Internal Pixel Clock Frequency = (2/3) * CLKI
FIL4286INCR[7:0]: Six equations required to find hex value
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}]
2
FILFSCONV[5:0] = int((27 * H_CLKO[11:0] * 1.087) / 1728 + 0.5)
For RGB input only:
MCR[7:0] = int ((920.26) / (288036.0 * H_CLKO[11:0] * SINX) * 226 + 0.5)
where SINX = [sin (p * Fsc / CLKI)] / (p * Fsc / CLKI)
MCB[7:0] = int ((598.15) / (288036.0 * H_CLKO[11:0] * SINX) * 226 + 0.5)
where SINX = [sin (p * Fsc / CLKI)] / (p * Fsc / CLKI)
MSC[31:0] = int ((282 / H_CLKO[11:0]) * 232 + 0.5)
MY = same as PAL, no change required for SECAM
For YCrCb input only:
MCR[7:0] = int
(1.902/(224*0.713)*(0.28/Fclk)/(84*SINX)*227+0.5)
MCB[7:0] = int
(1.505/(224*0.564)*(0.28/Fclk)/(84*SINX)*227+0.5)
MY = same as PAL, no change required for SECAM
1-74
Conexant
100381B
CONEXANT [ CONEXANT SYSTEMS, INC ]
