CS4216
Alternatively, soft power down may be initiated,
in slave mode, by reducing the SCLK frequency
below the minimum CLKIN/12. In soft power
down the analog outputs are muted and the serial
data from the codec will indicate invalid data
and the appropriate error code. The parallel bit
I/O is still functional in soft power down mode.
This is, in effect, a low power mode with only
the parallel bit I/O unit functioning.
audio data which reduces the number of bits on
the audio port from 64 to 32 per codec.
The serial port protocol is based on frames con-
sisting of 1, 2, or 4 sub-frames. The frame rate is
the system sample rate. Each sub-frame is used
by one CS4216 device. Up to 4 CS4216s may be
attached to the same serial control lines. SFS1
and SFS2 are tied low or high to indicate to each
CS4216 which sub-frame is allocated for it to
use.
Audio Serial Interface
Serial Data Format
In serial modes 1, 2, and 3, the audio serial port
uses 4 pins: SDOUT, SDIN, SCLK and SSYNC.
SDIN carries the D/A converters’ input data and
control bits. Input data is ignored for frames not
allocated to the selected CS4216. SDOUT car-
ries the A/D converters’ output data and status
bits. SDOUT goes to a high-impedance state
during frames not allocated to the selected
CS4216. SCLK clocks data in to and out of the
CS4216. The rising edge of SCLK clocks data
out on SDOUT. The falling edge latches data on
SDIN into the port (SCLK polarity is inverted in
Serial Modes 1&2). SSYNC indicates the start of
a frame and/or sub-frame. SCLK and SSYNC
must be synchronous to the master clock.
In serial modes 1, 2, and 3, a sub-frame is
64 bits in length and consists of two 16-bit audio
values and two 16-bit control fields. In serial
mode 4 a sub-frame is 32 bits in length and only
contains the two 16-bit audio values; the control
data is loaded through a separate port. The audio
data is MSB first, 2’s complement format. The
sub-frame bit assignments for serial modes 1, 2,
and 3, are numbered 1 through 64 and are shown
in Figures 5 and 6. Control data bits all reset to
zero.
CS4216 SERIAL INTERFACE MODES
Serial mode 4 is similar to serial mode 3 with
the exception of the control information. In serial
mode 4 the control information is entered
through a separate asynchronous control port.
Therefore, the audio serial port only contains
The CS4216 has 4 serial port modes, selected by
the SMODE1, SMODE2 and SMODE3 pins. In
all modes, CLKIN, SCLK and SSYNC must be
derived from the same clock source. SM1 is an
easy interface to ASICs that use a change in the
SCLK-to-CLKIN ratio to determine the sample
SMODE PINS Serial
SCLK Bit Sub-frame
Bits per
Frame (BPF)
SCLK &
SSYNC
Master
Frequency
3
2
1
Mode
Center
Width
0
0
0
0
1
0
0
1
1
x
0
1
0
1
x
SM1
SM2
SM3
Rising
Rising
Falling
64 bits
64 bits
64 bits
256
256
Slave
Slave
CLKIN = 512×Fs
SCLK = 256×Fs
64/128/256 Master/Slave
CLKIN/SCLK = 256×Fs
Factory Test mode
Falling 32 bits
†
†
SM4
32/64/128 Master/Slave
CLKIN = 256×Fs
†
Contains audio data only. Control information is entered through a separate serial port.
Table 1. Serial Port Modes
DS83F2
11
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