DATA29 datasheet(13/68 Pages) ETC2

13 / 68 page

Sys t e m Bus in te rface

ww w.d i gi .c om

System bus interface signal descriptions

RW_

I/O

Transfer direction

BR_

NO CONNECT

BG_

NO CONNECT

BUSY_

NO CONNECT

Mnemonic

Signal

Description

BCLK

Bus clock

Provides the bus clock. All system bus interface signals are

referenced to the BCLK signal.

ADDR[27:0]

Address bus

Identifies the address of the peripheral being addressed by the

current bus master. The address bus is bi-directional.

DATA[31:0]

Data bus

Provides the data transfer path between the NS7520 and external

peripheral devices. The data bus is bi-directional.

Recommendation: Less than x32 (S)DRAM/SRAM memory

configurations. Unconnected data bus pins will float during memory

read cycles. Floating inputs can be a source of wasted power.

For other than x32 DRAM/SRAM configurations, the unused data

bus signals should be pulled up.

TS_

Transfer start

NO CONNECT

BE_

Byte enable

Identifies which 8-bit bytes of the 32-bit data bus are active during

any given system bus memory cycle. The BE_ signals are active low

and bi-directional.

TA_

Transfer acknowledge

Indicates the end of the current system bus memory cycle. This

signal is driven to 1 prior to

tri-stating its driver.

TA_ is bi-directional.

TEA_

Transfer error

acknowledge

Indicates an error termination or burst cycle termination:

In conjunction with TA_ to signal the end of a burst cycle.

Independently of TA_ to signal that an error occurred during the

current bus cycle. TEA_ terminates the current burst cycle.

This signal is driven to 1 prior to tri-stating its driver.

TEA_ is bi-directional. The NS7520 or the external peripheral can

drive this signal.

RW_

Read/write indicator

Indicates the direction of the system bus memory cycle. RW_ high

indicates a read operation; RW_ low indicates a write operation. The

RW_ signal is bi-directional.

BR_

Bus request

NO CONNECT

BG_

Bus grant

NO CONNECT

BUSY_

Bus busy

NO CONNECT

Symbol

I/O

Description

DATA29 Datenblatt(PDF) 13 Page - List of Unclassifed Manufacturers

DATA29 Datenblatt(HTML) 13 Page - List of Unclassifed Manufacturers

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68

Datenblatt Download

Link URL