DS1251Y

032697 3/12

PHANTOM CLOCK

REGISTER INFORMATION

The Phantom Clock information is contained in eight

registers of 8–bits, each of which is sequentially ac-

cessed one bit at a time after the 64–bit pattern recogni-

tion sequence has been completed. When updating the

Phantom Clock registers, each register must be han-

dled in groups of 8–bits. Writing and reading individual

bits within a register could produce erroneous results.

These read/write registers are defined in Figure 2.

Data contained in the Phantom Clock register is in

binary coded decimal format (BCD). Reading and writ-

ing the registers is always accomplished by stepping

through all eight registers, starting with bit 0 of register 0

and ending with bit 7 of register 7.

PHANTOM CLOCK REGISTER DEFINITION Figure 1

7

654

32

10

1

100

01

01

0

011

10

10

1

010

00

11

0

101

11

00

1

100

01

01

0

011

10

10

1

010

00

11

0

101

11

00

C5

3A

A3

5C

C5

3A

A3

5C

BYTE 0

BYTE 1

BYTE 2

BYTE 3

BYTE 4

BYTE 5

BYTE 6

BYTE 7

HEX

VALUE

NOTE:

The pattern recognition in Hex is C5, 3A, A3, 5C, C5, 3A, A3, 5C. The odds of this pattern being accidentally dupli-

Clock LSB to MSB.