Appendix D Closed Caption Pseudo Code
CX25870/871
Flicker-Free Video Encoder with Ultrascale Technology
will be performed
//until CCF1B1 & CCF1B2 registers are
again written;
//null will be transmitted on appropriate CC line
in this case
Write ECCF1 to 1;
the CX870/871
//this is bit 4 of register C4 for
//Enables CC encoding on Field 1
//this is bit 5 of register C4 for
Write ECCF2 to 0;
the CX870/871
//Disables CC encoding for Field 2
if (625LINE == 0) //”625LINE” = bit 2 of register 0xA2
{
// 525-line format=NTSC is
being transmitted
//by CX870/871. This assumes
PAL-M = another //525 line
format is not allowed
[equation] CC_ADD = ($pow(2,
CBITS+5)/1716)*1716.0/H_CLKO;
//equation to determine CC_ADD
register for NTSC
CC_ADD_hex =
DEC_TO_HEX_CONVERSION(float CC_ADD);
//assumes
DEC_TO_HEX_CONVERSION
fxn //this should
already exist //some-
where in customer’s
code
Write CC_ADD(CC_ADD_hex);
//CC_ADD[11:0] register is
//comprised of
bits[3:0] of
//register 0xD4
and bits[7:0] of
//CX870/871 reg-
ister 0xD2
[equation] CCR_START =
H_CLKO*10.003*27/1716 + CC_PIPE1;
//eqn to determine CCR_START
register for NTSC
CCR_START_hex = DEC_TO_HEX_CONVERSION(float
CCR_START);
//assumes
DEC_TO_HEX_CONVERSION
D-2
Conexant
100381B
CONEXANT [ CONEXANT SYSTEMS, INC ]
