DSP56857 datasheet(429/662 Pages) FREESCALE

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Features

Host Interface Eight (HI8), Rev. 4

Freescale Semiconductor

16-3

16.1 Introduction

The Host Interface Eight (HI8) is a byte-wide, full-duplex, double-buffered, parallel port able to

be connected directly to the data bus of a Host Processor. The HI8 supports a variety of buses,

and provides connection with a number of industry standard DSCs, microcomputers, and

microprocessors.

Because the host bus can operate asynchronously to the core clock, the HI8 registers are divided

into two banks:

1. The Host Side bank is accessible to the external Host

2. The DSC Side bank is accessible to the core

The HI8 supports two classes of interfaces:

1. Host Processor/MCU connection interface

2. General Purpose Input/Output (GPIO) port

HI8 port pins not configured for peripheral use can be configured as GPIO pins.

16.2 Features

16.2.1 Dgital Signal Controller (DSC) Side

•

Four internal data I/O-mapped locations

•

Sixteen-bit data word

•

Transfer modes

—DSC-to-Host

— Host-to-DSC

— Host command

•

Handshaking protocols

— Software polled

— Interrupt driven

— DMA accesses.

•

Instructions

— Memory mapped registers allow the standard MOVE instruction to be used.

— Bit addressing instructions (i.e., BFCHG, BFCLR, BFSET, BFTSTH, BFTSTL,

BRCLR, BRSET) simplify I/O service routines.

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