PC87570 datasheet(16/168 Pages) NSC

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Introduction

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1.3.1

IRE Environment

In this environment, after reset, (internal power-on reset cir-

cuit or an external pulse on HMR pin), the PC87570 starts

running the code written in the internal mask-ROM. This

ROM contains the PC87570’s boot program which is read-

only. The boot-code size can be up to 2 Kbytes. After com-

pletion of the boot program, the process is handed over to

the External Memory. In the External Memory resides the

user-defined application.

The boot program performs several basic task needed to

start the system in a safe and ordered way. It checks if the

External Memory holds valid code. In case the code is in-

valid, it allows the host processor to re-program the Flash

device. See also Section B.1 on page 164.

To maximize on-chip ROM performance, configure the BIU

as described in Section 3.6 on page 46.

The majority of applications use the PC87570 in IRE envi-

ronment, which provides up to 10 on-chip I/O ports with a to-

tal of 76 GPIO signals. The ports are: PA6-0, PB7-0, PC7-

0, PD7-0, PE1-0, PF7-0, PG4-0, PH5-0, KBSIN7-0 and

KBSOUT15-0.

In addition, the PC87570 provides an interface to External

Memory and a variety of system functions, including ADC

and DAC, Timers, Interrupts, PM, ACCESS.bus/SMBus, and

other features (some features are mutually exclusive).

See Figure 1-1 for a system example in IRE environment.

In this environment, the ENV0 and ENV1 strap pins do not

need any external pull-up resistors.

Clock

External

Memory

PC87570

32KX1/32KCLKIN

32KX2

HMR

HA18-0

HD7-0

HIOR

HIOW

IRQ1

IRQ11

IRQ12

WR1-0

SEL0

A18-16, A15-0

D15-8

AD7-0

DA3-0

PA6-0

PB7-0

PC7-0

PD7-0

HIOCHRDY

RTC

Battery

VBAT

IRQ8

Crystal

32.768 KHz

External Keyboard

Internal

Keyboard

KBSOUT15-0

KBSIN7-0

SRAM or

Flash

ENV0

GA20

AVCC

AGND

VCC

GND

Power

Supply

SCL

D7-0

HMEMRD

HMEMWR

PG4-0

PE1-0

PF7-0

PH5-0

HMEMCS

HAEN

EXINT0,10,11,15

PFAIL

RING

SHBM

HRMS

Conﬁguration

Inputs

I/O

Expansion

HDEN

TRIS

HPWRON

PC0

External Mouse

Auxiliary PS/2

Interface

HRSTO

SELIO

(Matrix)

SDA

SWIN

Analog

Reset

Control

(power-up reset)

GPIO

Interrupt

ACCESS.bus

System

Timers

ENV1

Figure 1-1. IRE Environment

SEL1

(Application)

VREF

ADC

DAC

PC87570 Datasheet(PDF) 16 Page - National Semiconductor (TI)

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