SM5902AF datasheet(32/40 Pages) NPC

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User bit data

User bit data is data specified by the user. The data

is output, after the Q data has been specified, in the

following sequence.

012

456

789

000

•••

•

•••

••

1164

Q96

000

CTL0 CTL1 CTL2 CTL3

LBIT

L= 1

R= 1

CP1

CP2

000

112

000

128

000

144

000

160

000

176

000

- Using Q data

Initially, Q1 to Q80 are set using the 87H command,

the DIT flag is set using the 86H command, and

then data is output from DIT according to the digital

audio interface format. Q81 to Q96 data are not

required as these are set internally by CRC calcula-

tion.

There are 2 Q data buffers; a data output buffer

and a data storage buffer. As a result, after all data

has been specified in the first data write, only that

data that has changed needs to be written during

the 2nd and subsequent data write operations.

Note that address 1001 is the write stop command

and is, therefore, required after every data write

operation.

When space becomes available in the data output

buffer, QRDY is set to 1 (91H command status bit

S3) to indicate available space and then the con-

tents of the data storage buffer are transferred to

the data output buffer. After data is transferred, a

data write to address 1001 (write stop command)

resets the QRDY flag to 0.

The Q data buffer read access time for a complete

data cycle is approximately 13.3 ms.

Audio channel status

The channel status are information bits transferred

to indicate the audio sample data length, preem-

phasis, sampling frequency, time code, source

number, destination code, and other information.

Seven bits comprising CP1, CP2, LBIT, and CTL0

to CTL3 can be set. All other bits are fixed.

Subframe parity

The parity bit is used to indicate the detection of an

odd number of bit errors. It is set to 1 if the number

of 1s in the digital audio interface 27-bit data is odd,

and is set to 0 if the number of 1s is even. The 27-

bit data plus parity bit form 28-bit data that always

has an even number of 1s.

NIPPON PRECISION CIRCUITS-32

SM5902AF

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