ADSP-21MOD870 查看數據表（PDF） - Analog Devices

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ADSP-21MOD870

Internet Gateway Processor

Analog Devices 

ADSP-21mod870

Memory Interface Pins

The ADSP-21mod870 processor can be used in one of two

modes: Full Memory Mode, which allows BDMA operation

with full external overlay memory and I/O capability, or Host

Mode, which allows IDMA operation with limited external

addressing capabilities. The operating mode is determined by

the state of the Mode C pin during RESET and cannot be

changed while the processor is running.

Full Memory Mode Pins (Mode C = 0)

Pin Name

A13:0

D23:0

#

of

Pins

14

24

Input/

Output

O

I/O

Function

Address Output Pins for Pro-

gram, Data, Byte and I/O Spaces

Data I/O Pins for Program,

Data, Byte and I/O Spaces

(8 MSBs Are Also Used as

Byte Memory Addresses)

Host Mode Pins (Mode C = 1)

#

of Input/

Pin Name Pins Output Function

IAD15:0 16 I/O

A0

1

O

D23:8

IWR

IRD

IAL

IS

IACK

16 I/O

1

I

1

I

1

I

1

I

1

O

IDMA Port Address/Data Bus

Address Pin for External I/O,

Program, Data, or Byte Access

Data I/O Pins for Program,

Data Byte and I/O Spaces

IDMA Write Enable

IDMA Read Enable

IDMA Address Latch Pin

IDMA Select

IDMA Port Acknowledge

Configurable in Mode D; Open

Drain

In Host Mode, external peripheral addresses can be decoded using the A0,

CMS, PMS, DMS and IOMS signals.

Terminating Unused Pin

The following table shows the recommendations for terminating

unused pins.

Pin Terminations

Pin

Name

I/O

3-State

(Z)

Reset

State

Hi-Z*

Caused

By

Unused

Configuration

XTAL

CLKOUT

A13:1 or

IAD12:0

A0

D23:8

D7 or

IWR

D6 or

IRD

D5 or

IAL

I

O

O (Z)

I/O (Z)

O (Z)

I/O (Z)

I/O (Z)

I

I/O (Z)

I

I/O (Z)

I

I

O

Hi-Z

Hi-Z

Hi-Z

Hi-Z

Hi-Z

I

Hi-Z

I

Hi-Z

I

BR, EBR

IS

BR, EBR

BR, EBR

BR, EBR

BR, EBR

BR, EBR

BR, EBR

Float

Float

Float

Float

Float

Float

Float

High (Inactive)

Float

High (Inactive)

Float

Low (Inactive)

D4 or

IS

D3 or

IACK

D2:0 or

IAD15:13

PMS

DMS

BMS

IOMS

CMS

RD

WR

BR

BG

BGH

IRQ2/PF7

I/O (Z)

I

I/O (Z)

**

I/O (Z)

I/O (Z)

O (Z)

O (Z)

O (Z)

O (Z)

O (Z)

O (Z)

O (Z)

I

O (Z)

O (Z)

I/O (Z)

Hi-Z

I

Hi-Z

**

Hi-Z

Hi-Z

O

O

O

O

O

O

O

I

O

O

I

IRQL1/PF6 I/O (Z) I

IRQL0/PF5 I/O (Z) I

IRQE/PF4 I/O (Z) I

SCLK0

I/O

I

RFS0

I/O

I

DR0

I

I

TFS0

I/O

O

DT0

O

O

SCLK1

I/O

I

RFS1/IRQ0 I/O

I

DR1/FI

I

I

TFS1/IRQ1 I/O

O

DT1/FO O

O

EE

I

I

EBR

I

I

EBG

O

O

ERESET I

I

EMS

O

O

EINT

I

I

ECLK

I

I

ELIN

I

I

ELOUT O

O

BR, EBR

BR, EBR

BR, EBR

IS

BR, EBR

BR, EBR

BR, EBR

BR, EBR

BR, EBR

BR, EBR

BR, EBR

EE

EE

Float

High (Inactive)

Float

Float

Float

Float

Float

Float

Float

Float

Float

Float

Float

High (Inactive)

Float

Float

Input = High (Inactive)

or Program as Output,

Set to 1, Let Float

Input = High (Inactive)

or Program as Output,

Set to 1, Let Float

Input = High (Inactive)

or Program as Output,

Set to 1, Let Float

Input = High (Inactive)

or Program as Output,

Set to 1, Let Float

Input = High or Low,

Output = Float

High or Low

High or Low

High or Low

Float

Input = High or Low,

Output = Float

High or Low

High or Low

High or Low

Float

NOTES

**Hi-Z = High Impedance.

**Determined by MODE D pin:

Mode D = 0 and in host mode: IACK is an active, driven signal and cannot

be “wire ORed.”

Mode D = 1 and in host mode: IACK is an open source and requires an

external pull-down, but multiple IACK pins can be “wire ORed” together.

1. If the CLKOUT pin is not used, turn it OFF.

2. If the Interrupt/Programmable Flag pins are not used, there are two options:

Option 1: When these pins are configured as INPUTS at reset and function

as interrupts and input flag pins, pull the pins High (inactive).

Option 2: Program the unused pins as OUTPUTS, set them to 1, and let

them float.

3. All bidirectional pins have three-stated outputs. When the pins is configured

as an output, the output is Hi-Z (high impedance).

4. CLKIN, RESET, and PF3:0 are not included in the table because these pins

must be used.

REV. 0

–5–

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