Cirrus-logic EP73xx Bedienungsanleitung PDF herunterladen (Seite 119)

EP7309/11/12 User’s Manual - DS508UM4 15-1

1515

Chapter 15

15SSI Port

Introduction

The EP73xx provides two synchronous serial channels for use with audio devices,

telephony CODECs, and other devices using SPI or Microwire like communications

formats. The first of the two channels supports standard SPI and Microwire formats

for interfacing with low-bandwidth devices and is always associated with the SSI1

unit. The SSI1 interface is most commonly used to communicate with an A/D

convertor for digitizing pen input from a touch screen.

Features

• Dedicated general purpose SPI/Microwire1-compatible master mode

interface (SSI1)

• Selectable positive or negative edge clocking

• Compatible with many low speed ADCs, DACs, and other

peripherals

• 128 kHz max. clock with on-chip PLL (156.8 kHz at a CPU speed of

90 MHz)

• Compatible with external 13 MHz and PLL clock inputs

SSI Port Register List

Programming Example

;*****************************************************************************

; SSI Port 1 sending transmitting a request for data on the Maxim 148 ADC.

; Process requires sending config packet, receive data (byte to discard) send

; another byte, receive byte (real data) send another last byte, receive byte (real data).

; Total packet length is 24 bits. Extended mode off. ADCCON bit SYSCON3 is cleared.

;*****************************************************************************

Table 15-1: SSI Port Registers

Address Name Type Size Description Page

0x8000.0500 SYNCIO R/W 32

SSI ADC Interface Data

page 15-4

1 2 ... 114 115 116 117 118 119 120 121 122 123 124 ... 157 158

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