beautypg.com

Figure 11-10. 8-bit write cycle – Rainbow Electronics DS31256 User Manual

Page 160

background image

DS31256

160 of 181

Figure 11-10. 8-Bit Write Cycle

Motorola Mode (LIM = 1)
Arbitration Enabled (LARBE = 1)
Bus Transaction Time = 6 LCLK (LRDY = 0110)

An attempted access by the host causes the local bus to request the bus. If bus access has not been granted
(LBGACK deasserted), the timing shown at the top of the page applies, with LBR being asserted. Once LBG is
detected, the local bus grabs the bus for 32 to 1,048,576 clocks and then releases it. If the bus has already been
granted (LBGACK asserted), the timing shown at the bottom of the page applies.













LCLK

LBR

LBG

LBGACK

32 to 1,048,576 LCLKs

LA[19:0]

LD[7:0]

LD[15:8]

LR/

W

LDS

Address Valid

Data Valid

LBHE

Three-State

Three-State

Three-State

Three-State

Three-State

Three-State

LCLK

1

2

3

4

5

6

Note: LA, LD,

LBHE, LDS, and LR/W are three-stated.