CS5376 View Datasheet(PDF) - Cirrus Logic

Part Name

Description

MFG CO.

CS5376

Low Power Multi-Channel Decimation Filter

Cirrus Logic 

CS5376

SDTKI

SDRDY

SDCLK

SDDAT

MSB

LSB

Figure 46. Serial Data Output Port Transaction

10.2 Serial Data Transactions

To initiate a serial data output port transaction, the

SDTKI chip select pin must receive a rising edge.

If output data words are available in the data FIFO,

the CS5376 immediately pulls the SDRDY pin low

to signal the start of an SD port transaction. The SD

port holds SDRDY low until all data has been

clocked from the data FIFO.

Once SDRDY goes low, the communications con-

troller pulls 32-bit data words MSB first from the

SDDAT output pin by clocking the SDCLK input

pin. Serial data on the SDDAT output pin is valid

on the rising edge of SDCLK, and transitions on the

falling edge. The first eight data bits are a status

byte that indicates the channel number, the time

break flag, and any error conditions. The status

byte is followed by 24 bits of two’s complement

conversion data for the indicated channel. For sys-

tems that don’t require status information, the sta-

tus byte can be ignored by receiving the 32 bit data

word into a 24-bit shift register. Clocking 32 bits

into a 24-bit register causes the status bits to shift

out the end.

When the last available data bit is clocked from the

SD port data FIFO, the SDRDY pin returns high

and the SDTKO pin will pulse to signal the end of

the SD port transaction. SDTKO can be used to sig-

nal the communications controller of the end of a

transaction, or can be used to daisy chain multiple

CS5376 devices into a simple token ring by con-

necting it to the SDTKI pin of another CS5376 de-

vice.

If the SDTKI pin receives a rising edge and no

words are available in the data FIFO, the SDRDY

pin remains high and the SDTKO output pin is

pulsed immediately.

10.3 SD Port Configurations

The SD port can operate in two configurations, a

continuous output configuration where data is out-

put immediately when ready, or a requested output

configuration where data is output only when

polled by the communications controller.

Continuous Output Configuration

The continuous output SD port configuration re-

quires the SDTKI pin to receive continuous rising

edges. A simple method for generating rising edg-

es on SDTKI is to connect it to a 4 MHz or slower

system clock. Whenever output data is available

from the decimation engine, a rising edge on SDT-

KI initiates an SD port transaction.

Once an SD port transaction is initiated, the SDTKI

signal must be gated off to ensure no rising edges

DS256PP1

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