P i n o u t a n d P a c k a g i n g

 

 

 

 

 

 

 

 

 

 

 

 

 

Symbol

 

Pin

I/O

OD

Description

 

 

 

 

 

 

 

 

TEA_

 

C8 U

I/O

4

Data transfer error acknowledge

 

 

 

 

 

Add an external 820 ohm pullup to 3.3 V.

 

 

 

 

 

TEA_ is bidirectional. It is used in input

 

 

 

 

 

mode to terminate a memory cycle

 

 

 

 

 

externally. It is used in output mode for

 

 

 

 

 

reference purposes only.

 

 

 

 

 

 

 

RW_

 

D6

I/O

2

Transfer direction

 

 

 

 

 

 

 

BR_

 

D7

NO CONNECT

 

 

 

 

 

BG_

 

C7

NO CONNECT

 

 

 

 

 

BUSY_

 

B7

NO CONNECT

 

 

 

 

 

 

 

Table 2: System bus interface pinout

Signal descriptions

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.

Table 3: System bus interface signal description

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Digi NS7520 manual Signal descriptions, System bus interface signal description, Mnemonic Signal Description