EM78451AP datasheet(21/54 Pages) EMC

21 / 54 page

EM78451

8-Bit Microcontroller

Product Specification (V1.2) 05.27.2004

• 17

(This specification is subject to change without further notice)

PDRD

CLK

PCWR

PDWR

CLK

IOD

ROC

VCC

Weakly

Pull-up

PORT

Rex*

*The Rex is 560K ohm external resistor

PCRD

Fig. 7 (b) The Circuit of I/O Port with R-option (P80, P81)

4.5 SERIAL PERIPHERAL INTERFACE MODE

4.5.1

Overview & Features

Overview:

Figure 8, 9, and 10 shows how the EM78451 communicates with other devices through

the SPI module. If EM78451 is a master controller, it sends clock through the SCK pin.

A couple of 8-bit data are transmitted and received at the same time. However, if

EM78451 is defined as a slave, its SCK pin could be programmed as an input pin. Data

will continue to be shifted based on both the clock rate and the selected edge.

Features:

Operation in either Master mode or Slave mode,

Three-wire or four-wire synchronous communication; that is, full duplex

Programmable baud rates of communication,

Programming clock polarity, (RD bit7)

Interrupt flag available for the read buffer full,

Up to 8 MHz (maximum) bit frequency,

EM78451AP Datasheet(PDF) 21 Page - ELAN Microelectronics Corp