CS8420-CS Cirrus Logic Inc, CS8420-CS Datasheet - Page 26

• Manufacturer Part Number: CS8420-CS
• Description: Transceiver IC
• Manufacturer: Cirrus Logic Inc

Specifications of CS8420-CS

• Audio Control Type: Sample Rate Converter
• Supply Voltage Range: 4.75V To 5.25V
• Operating Temperature Range: -10°C To +70°C
• Audio Ic Case Style: SOIC
• No. Of Pins: 28
• Msl: MSL 2 - 1 Year
• Frequency Max: 108GHz
• Bandwidth: 20kHz
• Rohs Compliant: No
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

10. CONTROL PORT DESCRIPTION
The control port is used to access the registers, al-
lowing the CS8420 to be configured for the desired
operational modes and formats. In addition, Chan-
nel Status and User data may be read and written
via the control port. The operation of the control
port may be completely asynchronous with respect
to the audio sample rates. However, to avoid poten-
tial interference problems, the control port pins
should remain static if no operation is required.
The control port has 2 modes: SPI and I
CS8420 acting as a slave device. SPI mode is se-
lected if there is a high to low transition on the
AD0/CS pin, after the RST pin has been brought
high. I
AD0/CS pin to VD+ or DGND, thereby perma-
nently selecting the desired AD0 bit address state.
10.1 SPI Mode
In SPI mode, CS is the CS8420 chip select signal,
CCLK is the control port bit clock (input into the
CS8420 from the microcontroller), CDIN is the in-
put data line from the microcontroller, CDOUT is
the output data line to the microcontroller. Data is
26
CS
C C L K
C D IN
C D O U T
AND TIMING
2
C mode is selected by connecting the
ADDRESS
MAP = Memory Address Pointer, 8 bits, MSB first
0010000
C H IP
High Impedance
R/W
M A P
Figure 24. Control Port Timing in SPI Mode
MSB
b y te 1
2
C, with the
DATA
b y te n
LSB
clocked in on the rising edge of CCLK and out on
the falling edge.
Figure 24 shows the operation of the control port in
SPI mode. To write to a register, bring CS low. The
first 7 bits on CDIN form the chip address and must
be 0010000. The eighth bit is a read/write indicator
(R/W), which should be low to write. The next 8
bits form the Memory Address Pointer (MAP),
which is set to the address of the register that is to
be updated. The next 8 bits are the data which will
be placed into the register designated by the MAP.
During writes, the CDOUT output stays in the Hi-
Z state. It may be externally pulled high or low with
a 47 k resistor, if desired.
There is a MAP auto increment capability, enabled
by the INCR bit in the MAP register. If INCR is a
zero, then the MAP will stay constant for succes-
sive read or writes. If INCR is set to a 1, then the
MAP will auto-increment after each byte is read or
written, allowing block reads or writes of succes-
sive registers.
To read a register, the MAP has to be set to the cor-
rect address by executing a partial write cycle
which finishes (CS high) immediately after the
MAP byte. The MAP auto increment bit (INCR)
A D D R E S S
C H IP
0010000
R/W
MSB
LSB MSB
CS8420
DS245PP2
LSB