XRT8001IP datasheet(9/48 Pages) EXAR

9 / 48 page

XRT8001

Rev. 1.01

CSB

SCLK

SDI

R/W A0

SDO

High Z

Notes:

A4 and A5 are always “0”.

R/W = “1” for “Read” Operations

R/W = “0” for “Write” Operations

- Denotes a “don’t care” value

Simplified Interface Option

The user can simplify the design of the circuitry

connecting to the Microprocessor Serial Interface by

tying both the SDO and SDI pins together, and reading

data from and/or writing data to this “combined” signal.

This simplification is possible because only one of

these signals are active at any given time. The inactive

signal will be tri-stated.

Figure 6. Microprocessor Serial Interface Data Structure

Write Operation

Once the last address bit (A3) has been clocked into

the SDI input, the “Write” operation will proceed through

an idle period, lasting three SCLK periods. Prior to the

rising edge of SCLK Cycle # 9 (see Figure 6) the user

must begin to apply the 8-bit data word, that he/she

wishes to write to the Microprocessor Serial Interface,

onto the SDI input pin. The Microprocessor Serial

Interface will latch the value on the SDI input pin, on the

rising edge of SCLK. The user must apply this word (D0

through D7) serially, in ascending order with the LSB

first.

XRT8001IP Datasheet(PDF) 9 Page - Exar Corporation