CS8401 Datasheet, PDF (8/34 Pages) List of Unclassifed Manufacturers – Digital Audio Interface Transmitter

CS8401A
SDATA
SCK
FSYNC
D0-D7
A4-A0
8
6
7
21-24, 1-4
9-13
CS ¹⁴
16
RD/WR
15 Interrupt
INT
Control
Read
Address
Generator
Serial
Port
Logic
Control
and Flags
4X8
Buffer
Memory
28 X 8
Audio
Aux
C Bits
CRC
U Bits
Validity
Preamble
Parity
Biphase
Mux
Mark
Encoder
20
Line
Driver
17
TXP
TXN
Timing
IMCK
Prescaler
Figure 4. CS8401A Block Diagram
5
MCK
may be used to avoid contention between the
transmit pointer reading the data and the user up-
dating the buffer memory. Besides indicating the
byte location being transmitted, the flags indicate
the block of memory the part is currently ad-
dressing, thereby telling the user which block is
free to be written to. Each flag has a correspond-
ing mask bit (control register 1) which, when set,
allows a transition on the flag to generate a pulse
on the interrupt pin. Flag 0 and flag 1 cause in-
terrupts on both edges whereas flag 2 causes an
interrupt only on the rising edge. Timing and
further explanation of the flags can be found in
the buffer memory section.
The two most significant bits of control register 1,
BKST and TRNPT, are used for Transparent Mode
operation of the CS8401A. Transparent Mode is used
for those applications where it is useful to maintain
frame alignment between the received and transmitted
audio data signals. In Transparent Mode
(TRNPT = "1") the MCK, FSYNC, SCK and
SDATA inputs of the CS8401A can be connected to
their corresponding outputs of the CS8411. In Trans-
parent Mode, FSYNC synchronizes the transmitter
and the receiver. The data delay through the CS8401A
8
is set so that three frame delays occur from the
input of the CS8411 to the output of the
CS8401A. In Transparent Mode, 32 SCK’s are
required per subframe.
Channel status block alignment between the
CS8411 and the CS8401A is accomplished by
setting BKST high at the occurrence of the Flag
2 rising edge of the CS8411. If FSYNC is a
left/right signal, BKST is sampled once per
frame; if FSYNC is a word clock, BKST is sam-
pled once per subframe. A low to high transition
of BKST (based on two successive internal sam-
ples) resets the channel status block boundary to
the beginning.
Control register 2, shown in Figure 8, contains
various system level functions. The two most
significant bits, M1 and M0, select the frequency
at the MCK pin as shown in Table 1. As an ex-
ample, if the audio sample frequency is 44.1 kHz
and M0 and M1 are both zero, MCK would then
be 128× the audio sample rate or 5.6448 MHz. The
next bit (5) in control register 2, V, indicates the valid-
ity of the current audio sample. According to the
DS60F1