EM77950
BB Controller
9 Direction Serial Peripheral Interface (SPI)
9.1 Introduction
The EM77950 communicates with other devices via SPI (Direction Serial Peripheral
Interface) module, as shown in Fig. 9-1. To accomplish communication, SPI uses three
wire synchronous protocols: Serial Clock, Serial Data Output, and Serial Data. If the
EM77950 is a master controller, it sends clock through the SCK pin. An 8-bit data is
transmitted and received at the same time. If the EM77950, however, is defined as a
slave, its SCK pin could be programmed as an input pin. Data will continue to be
shifted on the basis of both the clock rate and the selected edge.
9.2 Features
3-wire, full duplex synchronous transceiver
Operation in either Master mode or Slave mode
Programmable baud rates of communication
Programming clock polarity
Programmable data transmission order
Interrupt flag available for read buffer full
Up to 8 MHz (maximum) bit frequency
9.3 Block Diagram
SDI
SDO
SCK
SCK
Clock
Clock
Generator
Generator
SDO
SDI
Shift Register (SPIS)
Shift Register (SPIS)
Read Buffer
(SPIRB)
Write Buffer
(SPIWB)
Write Buffer
(SPIWB)
Read Buffer
(SPIRB)
SPI Master
SPI Slave
Fig. 9-1 Typical SPI Transceiver Mode
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Product Specification (V1.0) 10.09.2007
(This specification is subject to change without further notice)
ELAN [ ELAN MICROELECTRONICS CORP ]
