Rabbit 2000 - 3.5 Interrupt Structure

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Designer’s

Handbook 39

11.

Hardware

Bring-Up

Procedure

When

a

user

has

designs

a

new

microprocessor

system

around

the

Rabbit

and

carefully

follows

the

Rabbit

design

conventions,

it

is

possible

that

the

system

will

not

boot

up

when

Dynamic

C

is

connected

to

the

programming

connector.

This

can

happen

because

of

a

design

error

or

even

because

of

a

random

hardware

defect

in

the

new

system.

A

hardware

procedure

is

available

to

make

it

easier

to

debug

systematically

in

such

a

situation.

A

series

of

steps

may

be

performed

in

order

to

diagnosis

a

problem

that

keeps

Dynamic

C

from

booting.

11.1

Initial

Checks

Perform

the

following

checks

with

the

/RESET

(pin

37)

line

tied

to

ground.

• With

a

voltmeter

check

for

the

+5

V

or

other

operating

voltage

on

pins

3,28,53,78,92

and

42.

Check

for

ground

on

pins

2,27,39,52,77,89.

• With

an

oscilloscope

check

the

32.768

kHz

oscillator

on

XTALA2

(pin

41).

Make

sure

that

is

is

oscillating

and

that

the

frequency

is

correct.

• With

an

oscilloscope

check

the

main

system

oscillator

by

observing

the

signal

CLK

(pin

1).

With

the

reset

held

low

this

signal

should

have

a

frequency

one

eighth

of

the

main

crystal

or

oscillator

frequency.

11.2

Diagnostic

Test

#2

This

test

goes

through

a

series

of

steps

repeatedly.

The

steps

are:

1. Apply

the

reset

for

approximately

1/4

second

and

then

release

the

reset.

2. In

cold

boot

send

the

following

sequence

of

triplet

characters

to

serial

port

A

via

the

programming

connector.

80 0E 20 // sets status pin low

80 0E 30 // sets status pin high

80 0E 20 // sets status pin low again

3. Wait

for

approximately

1/4

second

and

then

repeat

starting

at

step

#1

While

the

test

is

running

an

oscilloscope

can

be

used

to

observe

the

results.

The

scope

can

be

triggered

by

the

reset

line

going

high.

It

should

be

possible

to

observe

the

data

charac-

ters

being

transmitted

on

the

RXA

pin

of

the

processor

or

the

programming

connector.

The

status

pin

can

also

be

observed

at

the

processor

or

programming

connector.

Each

byte

transmitted

has

8

data

bits

preceded

by

a

start

bit

which

is

low

and

followed

by

a

stop

bit

which

is

high

(viewed

at

the

processor

or

programming

connector).

The

data

bits

are

high

for

1

and

low

for

0.

The

cold

boot

mode

and

the

triplets

sent

are

described

in

Section 3.1

on

page 5.

Each

trip-

let

consists

of

a

2-byte

address

and

a

1-byte

data

value.

The

data

value

is

stored

in

the

address

specified.

The

uppermost

bit

of

the

16-bit

address

is

set

to

one

to

specify

an

inter-

nal

I/O

write.

The

remaining

15

bits

specify

the

address.

If

the

write

is

to

memory

then

the

Table of Contents

Other manuals for Rabbit 2000

User Manual230 pages

Instruction & Reference Manual174 pages

Reference Manual120 pages

Getting Started Manual54 pages

Getting Started43 pages