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CS8416-IZ

192 kHz Digital Audio Interface Receiver

Cirrus Logic 

CS8416

6 CONTROL PORT DESCRIPTION

AND TIMING

The control port is used to access the registers, al-

lowing the CS8416 to be configured for the desired

operational modes and formats. In addition, Chan-

nel Status and User data may be read through the

control port. The operation of the control port may

be completely asynchronous with respect to the au-

dio sample rates. However, to avoid potential inter-

ference problems, the control port pins should

remain static if no operation is required.

The control port has 2 modes: SPI and I2C, with the

CS8416 acting as a slave device in both modes. SPI

mode is selected if there is a high to low transition

on the AD0/CS pin, after the RST pin has been

brought high. I2C mode is selected by connecting

the AD0/CS pin to VL+ or DGND, thereby perma-

nently selecting the desired AD0 bit address state.

6.1 SPI Mode

In SPI mode, CS is the CS8416 chip select signal,

CCLK is the control port bit clock (input into the

CS8416 from the microcontroller), CDIN is the in-

put data line from the microcontroller, CDOUT is

the output data line to the microcontroller. Data is

clocked in on the rising edge of CCLK and out on

the falling edge.

Figure 11 shows the operation of the control port in

SPI mode. To write to a register, bring CS low. The

first seven bits on CDIN form the chip address and

must be 0010000. The eighth bit is a read/write in-

dicator (R/W), which should be low to write. The

next eight bits form the Memory Address Pointer

(MAP), which is set to the address of the register

that is to be updated. The next eight 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 KΩ resistor, if desired.

There is a MAP auto increment capability, enabled

by the INCR bit in the MAP register. If INCR is a

zero, the MAP will stay constant for successive

read or writes. If INCR is set to a 1, the MAP will

auto increment after each byte is read or written, al-

lowing block reads or writes of successive regis-

ters. In the autoincrement mode, the MAP is

incremented in a linear fashion. Allowance must be

made for unused 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)

may be set or not, as desired. To begin a read, bring

CS low, send out the chip address and set the

CS

CCLK

C D IN

C H IP

ADDRESS

0010000

R/W

MAP

DATA

MSB

LSB

b y te 1 b y te n

C H IP

ADDRESS

0010000 R/W

CDOUT

High Impedance

MSB

LSB MSB

LSB

MAP = Memory Address Pointer, 8 bits, MSB first

Figure 11. Control Port Timing In SPI Mode

20

DS578PP2

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