HT85F2270 datasheet(190/226 Pages) HOLTEK

190 / 226 page

Rev. 1.00

190 of ��6

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Standard 8051 8-Bit Flash MCU

HT85F2260/HT85F2270/HT85F2280

35 Serial Interface – SPI

The SPI interface is often used to communicate with external peripheral devices such as sensors,

Flash Memory or EEPROM memory devices etc. Originally developed by Motorola, the four line

SPI interface is a synchronous serial data interface that has a relatively simple communication

protocol simplifying the programming requirements when communicating with external hardware

devices.

SPI Interface Operation

The SPI interface is a full duplex synchronous serial data link. The SPI interface is disabled or

enabled using the SPEN bit in the SPCON register which configures the functionally shared pins as

SPI pins and disables their logic I/O function. The SPI interface is a slave/master type, where the

device can be either master or slave decided by the MSTR bit in the SPCON register. It is a four line

interface with pin names, MOSI, MISO, SCK and SSN. Pins MOSI and MISO are the Serial Data

Input and Serial Data Output lines, SCK is the Serial Clock line and SSN is the Slave Select line.

Communication between devices connected to the SPI interface is carried out in a slave/master

mode with all data transfer initiations being implemented by the master. The Master also controls

the clock signal.

MI SO

MO SI

SC K

SS N

MI SO

MO SI

SC K

SS N

Sl av e

Ma st er

Single SPI Master and single Slave Connection

HT85F2270 Datasheet(PDF) 190 Page - Holtek Semiconductor Inc