Cirrus Logic CS5464 - Manual (Page 18)

CS5464
18 DS682F3
5.2.5 Serial Interface
The CS5464 provides 5 pins, SCLK, SDI, SDO, CS, and
MODE for communication between a host microcon-
troller or serial E
2
PROM and the CS5464.
MODE is an input that, when high, indicates to the
CS5464 that a serial E
2
PROM is being used instead of
a host microcontroller. It has a weak pull-down allowing
it to be left unconnected if microcontroller mode is used.
SCLK is used to shift and qualify serial data. Serial data
changes as a result of the falling edge of SCLK and is
valid during the rising edge. It is a Schmitt-trigger input
for host microcontrollers, and a driven output for serial
E
2
PROMs.
SDI is the serial data input to the CS5464.
SDO is the serial data output from the CS5464. It’s out-
put drivers are disabled whenever CS is de-asserted, al-
lowing other devices to drive the SDO line.
CS is the chip select input for the serial bus. A high logic
level de-asserts it, tri-stating the SDO pin and clearing
the serial interface. A low logic level enables the serial
port. This pin may be tied low for systems not requiring
multiple SDO drivers. CS is a driven output when inter-
facing to serial E
2
PROMs.