CS8411 datasheet(28/38 Pages) CIRRUS

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CS8411 CS8412

DS61F1

Professional Channel Status (C0 = 0)

When C0 is low, the received channel status block

is encoded according to the professional/broadcast

format. The Ca through Ce pins are defined for

some of the more important professional bits. As

listed in Table 7, Ca is the inverse of channel status

bit1. Therefore, if the incoming channel status bit 1

is 1, Ca, defined as C1, will be 0. C1 indicates

whether audio (C1=1) or non-audio (C1=0) data is

being received. Cb and Cc, defined as EM0 and

EM1 respectively, indicate emphasis and are en-

coded versions of channel status bits 2, 3, and 4.

The decoding is listed in Table 8. Cd, defined as

C9, is the inverse of channel status bit 9, which

gives some indication of channel mode. (Bit 9 is

also defined as bit 1 of byte 1.) When Ce, defined

as CRCE, is low, the CS8412 calculated CRC value

does not match the received CRC value. This signal

may be used to qualify Ca through Cd. If Ca

through Ce are being displayed, Ce going low can

indicate not to update the display.

Table 8. Emphasis Encoding

Consumer Channel Status (C0 = 1)

When C0 is high, the received channel status block

is encoded according to the consumer format. In

this case Ca through Ce are defined differently as

shown in Table 7. Ca is the inverse of channel sta-

tus bit 1, C1, indicating audio (C1 = 1) or non-audio

(C1 = 0). Cb is defined as the inverse of channel

status bit 2, C2, which indicates copy inhibit/copy-

right information. Cc, defined as C3, is the empha-

sis bit of channel status, with C3 low indicating the

data has had pre-emphasis added.

The audio standards, in consumer mode, describe

bit 15, L, as the generation status which indicates

whether the audio data is an original work or a copy

(1st generation or higher). The definition of the

Lbit is reversed for three category codes: two

broadcast codes, and laser-optical (CD’s). There-

fore, to interpret the L bit properly, the category

code must be decoded. The CS8412 does this de-

coding internally and provides the ORIG signal

that, when low, indicates that the audio data is orig-

inal over all category codes.

SCMS

The consumer audio standards also mention a serial

copy management system, SCMS, for dealing with

copy protection of copyrighted works. SCMS is de-

signed to allow unlimited duplication of the origi-

nal work, but no duplication of any copies of the

original. This system utilizes the channel status bit

2, Copy, and channel status bit 15, L or generation

status, along with the category codes. If the Copy

bit is 0, copyright protection is asserted over the

material. Then, the L bit is used to determine if the

material is an original or a duplication. (As men-

tioned in the previous paragraph, the definition of

the L bit can be reversed based on the category

codes.) There are two category codes that get spe-

cial attention: general and A/D converters without

C or L bit information. For these two categories the

SCMS standard requires that equipment interfacing

to these categories set the C bit to 0 (copyright pro-

tection asserted) and the L bit to1 (original). To

support this feature, Ce, in the consumer mode, is

defined as IGCAT (ignorant category) which is low

for the "general" (0000000) and "A/D converter

without copyright information" (01100xx) catego-

ries.

EM1 EM0 C2 C3 C4

Emphasis

CCITT J.17 emphasis

50/15

µs emphasis

No Emphasis

Not Indicated

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